References + Links

An ongoing and informal list of the links in each post, this will be updated as needed.

Tips to grow a lemon tree in a pot?, r/gardening: https://www.reddit.com/r/gardening/comments/17g9r4i/soooo_tips_to_grow_a_lemon_tree_in_a_pot/

Reddit Citrus page, r/citrus: https://www.reddit.com/r/Citrus/

Citrus Varieties to Try at Home, Robin Sweetser, May 30, 2024, Almanac: https://www.almanac.com/growing-citrus-containers

How To Grow Citrus Trees Indoors, By Arricca Elin SanSone, Updated on September 29, 2022 (Fact checked by Jillian Dara), Southern Living Magazine: https://www.southernliving.com/garden/how-to-grow-citrus-trees-indoors

How to Grow and Care for Citrus Trees Indoors: Add fresh lemons, limes, and oranges you grow at home to your fruit bowl with these expert guidelines, By Blythe Copeland, Published on July 26, 2023, Martha Stewart: https://www.marthastewart.com/how-to-grow-citrus-trees-indoors-7565868

USDA Plant Hardiness Zones Map: https://planthardiness.ars.usda.gov/

NPR, The USDA’s gardening zones shifted. This map shows you what’s changed in vivid detail, By Daniel Wood, Connie Hanzhang Jin, Brent Jones and Jeff Brady: https://apps.npr.org/plant-hardiness-garden-map/

4 CITRUS TREES Northern Gardeners Can Actually Grow!, The Millenial Gardener, YouTube: https://www.youtube.com/live/MpF9lWJKCuA

National Gardening Association Forum, Potted Citrus Tree INDOORS - How far should I hang my grow light?: https://garden.org/thread/view/143078/Potted-Citrus-Tree-INDOORS---How-far-should-I-hang-my-grow-light/

University of Minnesota Extension, Growing citrus indoors, Author: Deborah L. Brown (Reviewed in 2024): https://extension.umn.edu/houseplants/growing-citrus-indoors

Effect of Aluminium on Root Growth, Cell-division Rate and Mineral Element Contents in Roots of Vigna unguiculata Genotypes, W.J. Horst, A. Wagner, H. Marschner, Institut für Pflanzenernährung, Universität Hohenheim: https://www.sciencedirect.com/science/article/abs/pii/S0044328X83801998

What is the Difference Between Deep Watering and Overwatering?, Four Winds Growers, September 2023: https://www.fourwindsgrowers.com/a/blog/what-is-the-difference-between-deep-watering-and-overwatering

Four Winds Growers Citrus Tree Instagram: https://www.instagram.com/fourwindsgrowers/

California Department of Food and Agriculture, Transport of Privately-Owned House Plants Into California From Other States, Frequently Asked Questions: https://www.cdfa.ca.gov/plant/pe/InteriorExclusion/houseplant_FAQ.html

LA Times, Can I bring plants into California? Yes, but know the rules, By Catharine Hamm, Feb. 26, 2020: https://www.latimes.com/travel/story/2020-02-26/plants-allowed-into-california-regulations

California Department of Food and Agriculture, Bringing Plants Into California, Questions and Answers: https://www.cdfa.ca.gov/plant/factsheets/TransportingPlantsCA.pdf

Should I Repot My Calamondin And If So, How?, Citrus x microcarpa, By Kiersten Rankel, Jun 18, 2024: https://greg.app/how-to-repot-a-calamondin/

Insecticidal Soap vs. Neem Oil: Which Works Better?, Humboldt Secret Supply: https://humboldtssecretsupplies.com/blogs/articles/insecticidal-soap-vs-neem-oil-which-works-better

Insecticidal Soaps for Garden Pest Control, Factsheet | HGIC 2771 | Updated: Jul 30, 2021, Clemson University Extension: https://hgic.clemson.edu/factsheet/insecticidal-soaps-for-garden-pest-control/

Treatment for Spider Mites on Citrus, Discussion in 'Citrus' started by KevyWestside, Nov 8, 2019: https://forums.botanicalgarden.ubc.ca/threads/treatment-for-spider-mites-on-citrus.96747/

How to identify and treat spider mites, Written ByJen Greene, Posted: March 10, 2021, updated: 4/14/2024: https://trexplants.com/blog/how-to-identify-and-treat-spider-mites

Does Diatomaceous Earth Control Fungus Gnats?, Mosquito Company: https://themosquitocompany.co.uk/blogs/news/does-diatomaceous-earth-control-fungus-gnats

How to control pesky fungus gnats in my potted Calamondin, Lime, Lemon and Orange plants? Cheri Abraham, PhD, Entomologist & Operations Manager, US Citrus, LLC: https://uscitrusnursery.com/blogs/citrus-simplified/how-to-control-pesky-fungus-gnats-in-potted-calamondin-lime-lemon-and-orange-plants

Hobbiest Gardening: Growing Fruit Tree Plants from Seed, Many people mistakenly believe that fruit trees come true to name from seeds, but the seeds from a fruit actually produce a new variety that is a hybrid of two plants., Rob Crassweller, Ph.D., Former Professor of Horticulture, Pennsylvania State University, June 21, 2023: https://extension.psu.edu/hobbiest-gardening-growing-fruit-tree-plants-from-seed

From Root to Fruit: The Intricate Process of Growing Fruit Trees, Moana Nursery: https://www.moananursery.com/2023/04/07/from-root-to-fruit-the-intricate-process-of-growing-fruit-trees/

Nuceller Embrony, Wikipedia: https://en.wikipedia.org/wiki/Nucellar_embryony

Polyembrony, Wikipedia: https://en.wikipedia.org/wiki/Polyembryony

Citrus Polyembryony, Written By Angel Villegas-Monter, Elisa Del Carmen Matínez-Ochoa, María Andrade-Rodriguez and Itzel Villegas-Velázquez, Submitted: 21 April 2022 Reviewed: 21 June 2022 Published: 16 July 2022, From the Edited Volume: “Citrus Research - Horticultural and Human Health Aspects” Edited by Mateus Pereira Gonzatto and Júlia Scherer Santos: https://www.intechopen.com/chapters/82707

Please help me understand “true to seed”, r/gardening, Reddit: https://www.reddit.com/r/gardening/comments/qcxyfn/comment/hhiyswl/

HARDY CITRUS FOR THE SOUTHEAST, by Tom McClendon: http://citruspages.free.fr/Hardy%20Citrus.pdf

Redwood Barn Nursery, http://redwoodbarn.com/pdfindex.html

Redwood Barn Nursery, Which citrus fruits will come true to type from seed?: http://redwoodbarn.com/PDF/Whichcitrusfromseed.pdf

Citrus, Wikipedia: https://en.wikipedia.org/wiki/Citrus

We Finally Know Where Oranges and Lemons Come From, In addition to finding where citrus come from, researchers have pinpointed the genetic origins of the fruits’ tart taste, By Jack Tamisiea, October 11, 2023: https://www.scientificamerican.com/article/we-finally-know-where-oranges-and-lemons-come-from/

DNA story of when life first gave us lemons, 8 February 2018 Helen Briggs, BBC News: https://www.bbc.com/news/science-environment-42960445

Botanical classification of citrus fruits, Citrus Pages: http://citruspages.free.fr/classification.php#classification

“Apples & Most Fruit Are Not True to Seed” Paul C Hay, Extension Educator, University of Nebraska-Lincoln Extension: https://extension.unl.edu/statewide/gage/Apples%20&%20Most%20Fruit%20Are%20Not%20True%20to%20Seed.pdf

7 Citrus Tree Mistakes to Avoid, Epic Gardener, YouTube: https://www.youtube.com/watch?v=nd1ws1fwpqc&t=46s

Citrus Pruning | Cut, Pull & Bend Branches For MAX Fruit Yields! IV Gardening, YouTube: https://www.youtube.com/watch?v=jVbr5noPAQo&t=1111s

How to prune a lemon tree – expert tips to keep it in shape, By Melanie Griffiths, last updated 30 March 2023, Homes & Gardens Magazine: https://www.homesandgardens.com/advice/how-to-prune-a-lemon-tree

When and Where Should I Trim My Calamondin?, Citrus x microcarpa, By Kiersten Rankel, Jun 18, 2024: https://greg.app/how-to-prune-calamondin/

Indoor lemon tree. Should I prune or leave it as it is? r/Citrus, Reddit: https://www.reddit.com/r/Citrus/comments/y45nuf/indoor_lemon_tree_should_i_prune_or_leave_it_as/

Is it ok to cut off citrus tree thorns? Ask an expert, Published: Aug. 06, 2022, By Kym Pokorny | For The Oregonian/OregonLive: https://www.oregonlive.com/hg/2022/08/is-it-ok-to-cut-off-citrus-tree-thorns-ask-an-expert.html

Thorns On Citrus Trees: Why Does My Citrus Plant Have Thorns?, By Amy Grant, last updated 22 April 2021: https://www.gardeningknowhow.com/edible/fruits/citrus/thorns-on-citrus-trees.htm#

The Orchard People, The Simple Art of Grafting Fruit Trees: A Complete Guide: https://orchardpeople.com/grafting-fruit-trees/

What Is A Graft Collar And Where Is The Tree Graft Union Located, By Bonnie L. Grant, last updated 6 January 2023: https://www.gardeningknowhow.com/ornamental/trees/tgen/what-is-a-graft-collar.htm

University of Florida, Citrus Propagation, Publication #HS1309, Release Date: April 9, 2021: https://edis.ifas.ufl.edu/publication/HS1309

Natural Human History of Grafting and Budding, Cornell University: https://courses.cit.cornell.edu/hort494/mg/history/HistGB.html

How (&Why) To GRAFT FRUIT TREES | Figs, Apples, Citrus, Stone Fruit+, IV Gardening, YouTube: https://www.youtube.com/watch?v=98YjOBegVdU&t=1663s

Grafting Citrus Trees with the Patch Bud - Making a Fruit Cocktail Tree, Fruit Mentor, YouTube: https://www.youtube.com/watch?v=_w051zyackM

Grafting and Budding Nursery Crop Plants, Ted Bilderback, Director, JC Raulston Arboretum and Cooperative Extension Nursery Specialist Horticultural Science, R. E. Bir, T. G. Ranney, North Carolina State Extension, Publication date: June 30, 2014: https://content.ces.ncsu.edu/grafting-and-budding-nursery-crop-plants

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What I’ve learned about fruit tree grafting 🌱🌳🍋🍊🍏🍎🥑🍑🍒🥭🍐🍇

Something I was surprised to learn was that none of the citrus fruit we buy at the supermarket is grown from seeds in the ground, they’re all grown from grafted trees. Even the lemon and orange trees growing seemingly “wild” in people’s yards in places like Southern California or Florida are likely to be a grafted tree that was planted outdoors. 


Grafting involves cutting a scion from a proven fruit-bearing tree and attaching it to part of a separate rootstock it will grow off of, essentially as a clone. If you’re ever close enough to a citrus tree in a yard or in a grove, see if you can spot the graft collar close to the base of the trunk, it might be visible on a large enough tree.

Since most fruit trees don’t grow true to seed, there’s nothing wrong with the practice of grafting. This is not an especially modern method, grafting has been practiced for at least 2,000-4,000 years in various parts of the world.

As we are about to see for ourselves with this citrus adventure, it takes a long time and a lot of care to raise a fruit tree from seed, plus it takes years to start producing fruit, if it does at all. Based on what we’ve learned about the nature of citrus genetics, grafting is the only real way to grow fruit trees at any scale that are guaranteed to consistently produce desirable fruits. 

I also enjoyed various videos of professional arborists using all kinds of techniques to graft and grow different kinds of trees. 


Of course, you can let this tree grow as-is and let it live its natural lifecycle. Or, if you’re into this sort of thing, this tree could become a rootstock you can graft onto. Or, if it produces desirable fruit, then parts could be used as a scion.

I emphasize the distinction between grafted citrus trees and ones grown from seeds; the growing process is quite different. Any advice for grafted trees is less relevant than trees grown from seed; keep this in mind when you’re troubleshooting and researching for your tree in the future as it grows.

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Calamansi shoots in the sun (August 2024)

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All about pruning and long term growth 🪚✂️🍃🐝🌱🪴🌳

Since starting the first seeds in the summer of 2024, things have largely gone according to plan and over half of the seedlings are almost 1-foot tall and they’re starting to look like actual trees. Outdoors, these trees would grow to be 8-25 feet tall, but when grown indoors in containers, these might reach 2-4 feet tall. This, at 2 years old, is the start of a noticeable and possibly long awkward phase for the oldest specimens. But, we won’t lose hope: we’ll see this phase through and not give up on that tree! Yes, I’m telling myself this as much as I’m telling you! 


Aside from trimming off dead leaves and cutting the occasional water sprout on some of the seedlings, major pruning hasn’t been necessary yet and probably won’t be for another two years, likely even longer. Pruning directs energy towards producing flowers and fruits by eliminating dead branches and unhealthy growth, and the seedlings have responded to having dead growth trimmed off. Years from now, hopefully it’ll be growing strong enough where you’ll have to occasionally prune it to encourage branch growth and fruit production.

Because over-pruning can quickly kill a healthy tree, the consensus seems to err on the side of restraint . There are many, many resources available about pruning citrus trees. You should absolutely look these up, especially if you (like me) have never pruned anything before. Please feel free to get in touch to share your updates and progress! 

In a full grown tree, the best time to prune branches to control shape and growth is in the very late winter or early spring. This time of year is when trees emerge from dormancy just ahead of new growth, so the best and most productive branches experience peak season. Late season pruning is not recommended as you might mistakenly cut off forthcoming growth. 

These trees will produce thorns as they mature. Some of these young seedlings already grow small thorns. These are natural defenses to protect the tree and fruit from predators. It will produce thorns regardless of whether it produces fruit, and it may or may not stop growing them as it ages. The good news is: properly pruning the thorns won’t damage or harm the tree. In fact, because they could be a bit dangerous, this might be necessary if you have pets or young children. 


It will take at least 5-8 years or much longer, if it happens at all, but if your indoor specimen(s) produce flowers. Even if you keep it indoors without access to pollinators like bees, it’s still possible to pollinate the flowers by hand. If you are successful in your pollination methods, the flower parts might eventually (hopefully) mature into fruit! But it will probably grow some form of thorns the whole way. Ain’t that damn near poetic? 

A kumquat sprout in the sunlight, August 2024

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The question of fruit, and a word on citrus tree genetics 🍋🧬🍊🔬🍋🧬🍊

“Life, uh, finds a way.” 

(Jurassic Park, dir. Stephen Spielberg, Universal Pictures, 1993) 


It’s not guaranteed these shoots will grow into trees that flower and produce fruit, you’ll just have to wait and see. However, even if they never flower or produce fruit, you will still have a lush miniature tree with shrub-like, sweet-scented deep green leaves. 


The reason citrus trees do not always bear desirable fruit is because of the mixed parental genetics within the seed itself. Citrus seeds are frequently nucellar polyembryonic seeds, meaning there’s more than one embryo per seed. 

In short, plants do this to create genetic variation to increase its chances of survival. Seeds with varying copies of its genetic material with different potential traits to express are more likely to survive and adapt than identical single copies. In fact, with a few exceptions, most fruit trees are not “true to seed,” or, will not produce fruit identical to the tree it came from. 

The calamansi almost always sprouted multiple shoots. The kumquats almost always sprouted single shoots. If you have a polyembryonic shoot, you might have to select the strongest shoots for long term growth at your discretion. Re-pot and grow them separately; as one will inevitably take energy from the other. 

With polyembryonic seeds like most of the calamansi, it’s likely that shoots of multiple parentage within one seed have sprouted, and one of these will grow true to seed. The monoembryonic seeds that only grew one shoot, like almost all of the kumquats, are not likely to grow true to seed and won’t produce fruit like the parent tree. 

The seeds I planted contain genetic material from multiple generations of everything those fruits were a hybrid of. This is not unlike how we humans are the product of two parents but don’t have identical traits or genes of solely one or the other. As offspring, we may resemble one another and both parents, but we’re not always exactly alike, and certain traits are not always guaranteed to be expressed. 

In the case of fruit trees, the resulting fruit you grow might be the same as, or better than, or (more likely) worse than the fruit the seed came from. The odds are high that it will be different somehow.

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All citrus fruits are hybrids of two or more original species: the citron, the pomelo, and the mandarin orange. These ancestral species originated in various tropical and sub-tropical regions of the Asian continent (India, Southeast Asia, and China). The drastic periods of climate change during the Miocene and Pliocene epochs (between 23M and 5M years ago) enabled these ancestor species to grow wild, with specimens and pollen samples dating back to these periods; eventually leading to human cultivation starting around 6,000-3,000 years ago.

Today, we know the descendants of these ancestral fruits as oranges (mandarin + pomelo), lemons (bitter orange + citron), grapefruits (sweet orange + pomelo), tangerines (mandarin orange varieties + pomelo), Meyer lemons (mandarin + citron + pomelo), Clementines (sweet orange + mandarin), and more.

Kumquats are classified as citrus japonica, and contain different cultivars (Meiwa, Nagami, etc.). The seeds I germinated and planted almost always grew one shoot, or, are monoembryonic. 

Calamansi are a hybrid of mandarin orange + kumquat. I noticed that the Calamansi seeds were almost always polyembryonic, and grew multiple shoots, all of which show slightly variable traits and leaf shapes. I didn’t label Group 1 so my labels are educated guesses, based on leaf shape. 

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Obnoxious Beasts (And How To Kill Them) 🦟🐜🐞🪰🔫

An ongoing list of common citrus tree pests and how to eliminate them. As this is my first time growing citrus trees, I have limited first hand experience dealing with most pests, so I’m keeping this here for the inevitable need and will be updating as I go.

Fungus gnats: harmless swarms will come and go and they aren’t necessarily a sign of anything bad, they’re inevitable when there’s excessive moisture in the soil. While they’re not strong fliers and don’t bite, they’re still a nuisance. You can control or eliminate them by using both sticky traps and diatomaceous earth together, along with letting soil dry out completely between waterings. Two years into growing the seedlings inside my apartment with occasional fungus gnat infestations, the best solution I’ve found is a combination of Mosquito Bits used for watering (kills larvae in the soil) and a lot of strategically placed sticky traps to trap the adults when possible. Mosquito Bits specifically work faster than mosquito dunks, even though they have the same ingredient.


Spider mites: these are more likely to be a problem on more mature plants, they’re a little harder to get rid of than fungus gnats. They are extremely small, smaller than a pinhead, so you’ll have to look at the leaves very closely to see them. Gently wipe the tops and bottoms of every leaf with insecticidal soap or Neem oil; expect do do more than one round of this for multiple days. Insecticidal soap works best for soft bodied insects and works quickly to reduce infestations, and somewhat gentler on leaves than neem oil. Diluting Neem oil with water will help prevent leaf burning, along with washing off the leaves with a clean damp towel to mimic rainfall. Neem oil has a really strong odor, and while it’s generally non-toxic and safe to use on fruits and vegetables grown for consumption, avoid splashing it on your face and wash your hands thoroughly after handling neem oil products.

Thrips:

I have not experienced this pest as of this writing so I’m leaving these resources here just in case:

https://www2.ipm.ucanr.edu/agriculture/citrus/Citrus-Thrips/

https://www.thegreenpinky.com/best-insecticides-thrips/

Scale:

I have not experienced this pest as of this writing so I’m leaving these resources here just in case:

https://www.fruitsaladtrees.com/pages/citrus-scale

https://www.reddit.com/r/Citrus/comments/14y33o4/scale_treatment/

https://www.gardeningknowhow.com/edible/fruits/citrus/controlling-citrus-scale.htm

https://www.finegardening.com/article/controlling-scales-a-common-pest-of-fruit-trees

Citrus Leafminer:

I have not experienced this pest as of this writing so I’m leaving these resources here just in case:

https://extension.uga.edu/publications/detail.html?number=C1145&title=how-to-control-citrus-leafminers

https://www.yamagamis.com/blog/how-to-treat-citrus-leafminers

https://www.agric.wa.gov.au/pest-insects/citrus-pests?nopaging=1

https://www.engalls.com.au/advice/citrus-pests-and-diseases/

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Re-potting, soil health, root development, and room to grow 🪴⏳📏🗓️📈

“No! Try, not. Do or do not; there is no try.” 

(Yoda, The Empire Strikes Back, dir. Irvin Kershner, 20th Century Fox, 1980)

Citrus trees are best put in a container where roots aren’t touching the ground. Soon it will make sense to keep the potting container with drainage holes suspended inside a larger container, and I’ve found that containers made of terracotta or plastic work better than glass or glazed ceramic. Do not let the roots or the container sit in standing water. It might be tempting to bottom water these to mimic the water table of being planted in the ground, but for an indoor lemon tree, I don’t recommend this method. Bottom watering too easily introduces root rot and soil rot, while top down watering lets the water flow out through the soil and container drainage holes. In this case it’s best to not mimic nature and just work with the circumstances of indoor planting.


Because these are still young seedlings (1-2 years) and because I grow indoors exclusively, I just repot when the roots are growing past its current container or when the soil is exhausted, regardless of the time of season. When the tree is more mature (in anywhere from 5-8 years or more), the time of the season will be more important when growing in Zones 6-7. Most sources suggest the sweet spot for this late winter or early spring, when they’re when emerging from seasonal dormancy. Generally, it’s not recommended to re-pot mature trees when fully dormant in the late autumn and winter, and peak season growth could be interrupted by re-potting too late into summer.

Choose a container one size bigger, but avoid an overly large one. Soil will trap excess moisture in an overly large container and create rot. Think of it like buying shoes for growing children; you have to prioritize for short term growth so the shoes stay on their feet today, because jumping straight into adult size shoes would be impractical and counterproductive. 


In my first experiment with the very first group of lemon shoots (RIP), I used both tall and deep containers and a shallow and wide one. I noticed the shoots seemed to do better in the tall/deep style. The eldest seedlings (currently 2 years old and between 9-12 inches tall) have been in tree pots since late 2025. I did this to encourage downward taproot development, minimize root circling, and encourage vertical growth. After they outgrow the tallest tree pot I have, I will probably look into a larger and wider container for the growing tree.

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I’ve had to improvise soil mixtures and ratios over the past two years to find what works best. The wrong soil mixture is probably the second biggest reason why I lost so many seedlings at the earliest stages. Growing indoors in containers makes creating a healthy soil ecosystem from first principles challenging. Through trial and error, I currently use a combination of a very chunky Orchid mix, NYC’s finest compost, perlite, vermiculite, earthworm casings, soil acidifier, and a tiny sprinkling of Osmocote fertilizer.

Initially each seedling was planted with the following mixture: Miracle Grow Cactus, Palm & Citrus Potting Mix, Espoma Organic Soil Acidifier, beach sand, Osmocote flower & vegetable plant fertilizer, and diatomaceous earth (fungus gnat prevention).

I found that a very chunky orchid specific soil mix is much better than the cactus mix, and they’re not interchangeable. The orchid mix is primarily wood bark pieces that allow for drainage, whereas the cactus mix tends to have more moss and potting soil. These major differences enable different types of root development, and citrus trees need lots of drainage space and to retain less water than more. I now also use a significant amount of perlite and vermiculite to aid drainage.

In August 2025, I introduced NYC compost to the soil mix, and this past spring of 2026, I introduced worm castings to the mix. Both are going over very well so far. Citrus trees are heavy feeders, so at first I thought that giving them more fertilizer would be better, but this was a mistake because the seedlings frequently got fertilizer burn, so I stopped adding it to the soil mix. The compost and worm castings are a much better, healthier source of nutrients than fertilizer. Now I just apply fertilizer topically as needed, which is much less frequently than I thought.

I stopped using beach sand because it wasn’t doing anything significant and was getting heavy to transport. So far I’ve found that whatever the regular sand was doing could be done better by perlite and vermiculite. A very coarse horticultural sand, or even chicken grit, might be a “nice to have” option in the future, but regular sand is not an absolute necessity.

Diatomaceous earth is something I add topically to the surface on an as-needed basis to keep fungus gnats away. But it gets very mushy and muddy when wet, and is no longer effective, so I don’t add it to the soil mix anymore.

I add soil acidifier because citrus trees generally do better in acidic soil. If you’re not familiar with this brand of acidifier, the way Espoma works is the sulfur chips are dissolved by organisms in the soil which convert it to sulphuric acid. The gypsum counteracts the development of toxic soluble aluminum that results from acidifying the soil. The Espoma brand is a “slow release” formula that takes about 6 months to reach potency. Other types of acidifiers are available, your mileage may vary. 

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This is about water requirements 💦💧🌧️🚿🚰🌱🪴🌿🍊🍋

“…next to you, we ALL have a drinking problem!” 

(Burn After Reading, dir. The Cohen Brothers, Focus Features, 2008) 

Watering citrus trees is not intuitive for newcomers. The biggest reason I lost so many seedlings at the earliest stages of this (summer 2024) is because I didn’t get the water right. I’ll try to explain below the best methods and highlights I’ve learned in this process.

Citrus trees are VERY particular: they don’t tolerate sitting in dampness, and they can’t drink too much or too little. They need infrequent, deep waters, not regular, surface waters. However often you water other plants, citrus trees need it less frequently than you would expect. They like a solid binge and then dry out almost thoroughly between sessions. When in doubt, just let it dry out.

During peak summer in warm conditions, watering every 7-10 days seems to work. Sometimes they will need it more often (say, during a heatwave of 100+ degree temperatures), and sometimes they need longer than 10 days to dry out the soil; I just monitor them. However, during the winter, I water significantly less, maybe only once or twice a month. And, I’ve found that keeping the soil a tiny bit moist (though not super damp) during the winter helps the roots tolerate the colder air, absorb nutrients, and keeps the soil from becoming brittle.

While it’s all too easy to over-water these, they can’t be left completely dry for too long, either; the roots will eventually dehydrate. An indication to water is if the top layer of soil is visibly dry, check by testing soil dampness by hand, or with a bamboo skewer. The leaves will also noticeably droop down and even fall off when severely dehydrated.

Citrus roots are especially prone to root rot, so the soil mix must be well-draining. Using compacted soil that doesn’t drain well will kill it very quickly. 

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These measurements are not definitive, this is just what’s worked for me so far. Your mileage may vary and your research may lead you to other conclusions. Again, you’re welcome to share your progress in the comments!

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Say more about light requirements and Growing Zones ☀️🌤️🌞🪴🌱

Citrus trees need 6-10 hours of sunlight for the entirety of their lifetimes. This might be the least negotiable of all the requirements to grow citrus; i.e. it will not survive without enough sunlight, regardless of whether you water it perfectly in a warm environment in fertile soil.

Direct sunlight must be available. Here’s the twist, though: because it’s possible for them to get sunburned or heat-stressed, ideally there’s an option for bright indirect light in case it ever needs to cool off temporarily. If it’s showing signs of heat stress, move it to indirect sunlight for a day or more, and give it a full watering if needed. The reason they’re tolerant to some indirect light is because citrus trees originated and evolved as an understory species starting around 8 million years ago in the Himalayas in southern China. I discuss the genetics and some of the evolutionary history of citrus species in another post.

South facing windows with access to consistent daylight from east and west are ideal. I happen to have this exact setup in my living room, and in Zone 7b it’s just enough. In peak conditions in the spring, summer, and early fall, it needs 8-10 hours of direct sunlight. In the late fall and winter months, strive for 6-8 hours of direct sunlight. When natural sunlight isn’t available (e.g. in zones 7 and below) an artificial grow light is recommended to make up for the loss.

Citrus trees thrive between 60-90F. Mild to moderate humidity is ideal, and you can substitute with misting or use a humidifier in a dry climate (or, a nyc apartment microclimate). Generally, the warmer the better as far as temperature goes. Choose the least-drafty, most consistently warm and sunny spot you have available. However, putting it directly on a radiator is not ideal and is likely to kill it off.

I do not recommend keeping it in an excessively damp environment (like inside a shower), as the roots prefer to be dry and are highly prone to rot when too damp. And while I just said heat is better than cold, excessive direct heat isn’t ideal either, as the shoots will experience sunburn, heat stress, and wilt at temps above 110F. 

Citrus trees thrive between US Zones 9, 10, and 11. In the US, these are the only Zones where they can be planted and grown outdoors year round. Below are USDA hardiness zone resources, but the NY tristate area is in Zone 7. Here, growing citrus trees will be a largely indoor endeavor.

Here’s a cheat sheet of the USDA growing zones in the northeast: 

  • The NYC area and the tristate area (including NJ and the Philadelphia, PA region) is in Zone 7b. 

  • Just north, the area from Hudson Valley up towards Albany, as well as the neighboring region of southwestern New England (western Connecticut and Massachusetts), is in Zone 6a. 

  • Farther north, towards upstate NY (i.e. the longitude between Saratoga to Syracuse and Rochester) is designated as Zone 5b.

  • Eastern Massachusetts in the Boston metro area and back bay, Suffolk County, Plymouth County, and Cape Cod are between Zones 7a to 7b. 

Look up your growing zone on the USDA website: https://planthardiness.ars.usda.gov/ 

This article from NPR also has useful information about the recent updates to the zone map: https://apps.npr.org/plant-hardiness-garden-map/ 

In short, do not plant this tree outdoors in Zones 5-7 and expect it to survive. The winters here are too cold, too dark, and last too long. There are ways to attempt this in cooler zones (e.g. Zone 8), but it takes a lot of work, expertise, and investment to protect the trees from frost.  

Do not let the young shoots sit outside in any conditions, for any reason. Even light breezes will blow over and break immature shoots, which I learned the hard way with my very first group of lemon tree shoots (RIP). When they’re very young and delicate, I don’t even recommend keeping them near an open window; the breeze might be too strong. 

My very first group of lemon shoots, which I started in late March, died a sudden, painful death in late May. One day, I put them outside on my fire escape for a few hours for the daylight, and the summer breeze broke the delicate shoots and killed them all. 

So, as tempting as it is to let them photosynthesize outdoors, keep young specimens indoors away from the elements for as long as possible. As they have matured 1-2 years old now, I still keep them indoors but I let them be near open windows. In the future it might make sense to move them outdoors on a part-time basis (e.g. to a sunny porch on nice days only in the summer), staking it so it’s more secure, but I don’t think they’ll be ready for that for at least another year or more. 

Between July 2 and August 4, I planted the germinated seeds in basic 3.5 oz. plastic cups that I hand-cut drainage holes into, and sprouted them in makeshift mini greenhouses with plastic dollar store bins. By late winter/early spring 2025, it will be time to transplant to a slightly larger cup. 

You will have far fewer to care for than I did, but here are photos of my setup for Group 1 shoots in my bathroom (about 56x). It got a little crazy in there.

Back To Intro

All about these shoots

“Come play with us…”

(The Shining, dir. Stanley Kubrick, Warner Bros., 1980)

During the summer of 2024, I unintentionally acquired three types of citrus seeds: lemon, kumquat, and calamansi. With no experience growing any kind of tree before, I peeled off the outermost, beige colored, protective hull of each seed, then germinated the seeds by folding them into damp paper towels in plastic bags. That summer and up until February 2026, for every lemon I’d buy from the grocery store I’d keep a few seeds and plant the ones that sprouted. Before I knew it, I had dozens and dozens of seedlings growing in my Brooklyn apartment. Now, two years later, I have 28 total specimens currently thriving and growing.

I’m not especially experienced or skilled at caring for indoor plants, in fact more than one ZZ plant and a pothos has died in my care. I wasn’t convinced these would last very long when I started this on a whim, but once I got a few of them going, it became a lot of fun to keep up the progress. This has been a fun, low-ish cost, indoor hobby and I’m surprised by how much fulfillment I’ve found in caring for these growing trees. It turns out you don’t need lots of money or skills to grow something; just observant patience, willingness to do a little research and learn, and resourcefulness to improvise solutions.

That said, citrus trees are the opposite of a passive-care plant like a snake plant or a ZZ plant; you cannot completely ignore them for extended periods of time. Especially in Zones 6-7, and especially as immature specimens, they do require active attention year round.

They require significant amounts of sunlight (or a grow light), a very specific watering routine, and a soil mix that’s very well draining but also nutrient dense. In the beginning, I lost a lot of seedlings because I got one or all of these factors wrong, I’ve kept this blog as a way of tracking my progress, and as a reference for anyone else who wants to adopt one of these seedlings in the future.

Calamansi, Kumquat, and Lemon Seedlings Overview:
The first date is when I started germinating them, the second date is when I planted the sprouts. 

  • Group 1: Germinated 6/26/24, Planted 7/2/24 (calamansi, kumquat, and 1x lemon)

  • Group 2: Germinated 7/2/24 and 7/7/24, Planted 7/16/24 (calamansi and kumquat)

  • Group 3: Germinated 7/17/24, Planted 8/4/24 (all lemon)

  • Group 4: Germinated 8/12/24, Planted 8/25/24 (all lemon)

  • Group 5: Germinated 11/12/24, Planted 12/6/24 (all lemon)

  • Group 6: Germinated 1/20/26, Planted 2/15/26 (all lemon)


The origin of these seeds are as follows: 

  • Calamansi: seeds were saved from fruits that were available through work. I started with over a dozen shoots but now in 2026 only two have survived.

  • Kumquat: purchased packaged kumquat fruits from two sources, the supermarket in northwest Connecticut, and from packaged fruits from a street seller in NYC Chinatown. I started with almost 24 shoots but now all but one have survived.

  • Lemons: most info points to the lemons probably being either Eureka or Lisbon lemons, which are most commonly found in supermarkets (where I found these) but I am not certain. I started well over 60-70 lemon seeds at first in different stages, but today I have 25 surviving lemon seedlings.

Between July 2 and August 4, I planted the germinated seeds in basic 3.5 oz. plastic cups that I hand-cut drainage holes into, and sprouted them in makeshift mini greenhouses made of plastic dollar store bins. On August 25, I transplanted those seedlings to larger 7 oz. cups.

Today, half of the seedlings today live in clear plastic lidded containers that act as greenhouses with each seedling growing in a 16 oz. clear plastic cup with hand cut drainage holes, and the other half are too tall to be kept covered and are currently growing in plastic tree pots.

All citrus trees are rather vulnerable to diseases and fungal infections which become very difficult and costly to control. Using soil or tools that were exposed to diseased plants, or if you use containers that haven’t been thoroughly cleaned, the tree will have issues from the start. 

Because citrus trees are so vulnerable to disease and pests, and because almost all the citrus trees growing in California are grafted clones with little natural built in protection against hitherto unknown diseases, the state of California highly regulates all citrus plants, fruits, and leaves entering the state via flight and freight. One can easily drive into the state with plants in a personal vehicle, nobody checks that anywhere, but you are running the risk of introducing pests and diseases to native trees. So, if you care about the health of tree species on a larger scale: Do not transport these trees into the state of California, it’s technically illegal.

Back To Intro

Project Pomona: Introduction 🍊⚜️🍊

Welcome!

If you are reading this, then you are someone I know who is interested in learning more about the kumquat, calamansi, and lemon tree shoots I’ve been growing from seed.

Maybe you identify as an intermediate (or above) plant person, and are interested in acquiring a couple of these citrus tree seedlings for yourself (I would love to give you some, please inquire!). 

CONTENT LINKS:

  1. All About These Shoots

  2. Say more about light requirements and hardiness zones ☀️🌤️🪴🌱

  3. This is about water requirements 💦💧🌧️🚿🚰

  4. Re-potting, soil health, root development, and room to grow 🪴⏳📏🗓️📈

  5. Pests 🦟🐜🪰🔫

  6. The question of fruit, and a word on citrus tree genetics 🍊🍋🧬🔬🧬 

  7. Misc. notes on long term development, also get excited about pruning 🪚✂️🍃🐝🌱🪴🌳

  8. What I’ve learned about fruit tree grafting 🌱🌳🍋🍊🍎🥑🍑🍒🥭🍐

  9. References + Links

To be clear: this is my first time growing any kind of tree indoors, I’ve been learning as I go. I’m sharing what I’ve learned so far as a series of ongoing notes for myself, and if it helps anyone else searching for the exact same information I did.

Citrus tree care is not always intuitive for first time growers like me, I’ve discovered there is a learning curve. Since this spring, I’ve done a lot of online research on how to grow citrus trees indoors. And it’s fascinating! 

For anyone interested in staying connected on our shared citrus adventure, I have turned comments on so you can share updates on your progress, anything that I haven’t covered that is working, and any new information they’ve learned.

🍊⚜️🍊

A minor Roman deity, with no Hellenic equivalent, Pomona is a wood nymph who watches over and protects fruit bearing trees and cares for their cultivation. Her sacred attribute is a pruning knife. The Roman poet Ovid described her pure, radiant beauty and her passion for gardening in Book 14 of his narrative poem, Metamorphoses. 

Her name originates from “pomum,” the Latin word for orchard fruit, the French word for apple (“pomme”) is subsequently derived from this; and she is often associated with apples and apple trees. Only two types of citrus fruits were known to Ancient Romans, the citron and the lemon, and they would have been either status symbols to the elite, or used in ceremonial or medicinal purposes. Cultivated fruits such as apples, pears, quinces, plums, figs, and pomegranates were more commonly consumed.

Although Pomona is also frequently depicted in a orchard or garden, often with a cornucopia of fruits, she is not associated with the act of harvesting, but with the flourishing, abundance, and divinity of the trees themselves. 

🍊⚜️🍊