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Growing Tomatoes—Indoors!

by Kenneth Moore (indoorgarden_er)

Super Bush tomatoes ripening at the end of November--indoors!
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The Indoor Garden(er)'s insight into how to grow tomatoes if you don't have a yard--indoors!

Right now, most gardeners are done taking care of fall garden chores and might be thinking about what to plant in next year's vegetable garden. Some of us, however, are still harvesting tomatoes—even when it's below freezing outside.



Yeah, that's right. These beauties are ripening on the vine—on my windowsill! I have been experimenting growing indoor tomatoes for two years. Below, I have advice from my own indoor tomato experiences, but I have found this site to offer helpful advice, as well. I consider indoor tomatoes to be a supplement, a fun experiment (for yourself or particularly for patient, plant-loving children), or a conversation piece throughout the year, not a primary source of tomato-y goodness. Understanding the limitations of growing edibles indoors and the differences between how they grow in the home and how they grow in optimum conditions will allow indoor gardeners to have more realistic expectations of what these plants will do for them.


Selecting Tomatoes


Any gardener should select plants that will thrive in his or her garden, and growing tomatoes indoors is no different. If starting from seed, early winter is a perfect time to start doing research on what might be the best variety to grow—descriptions such as “container” and “dwarf” are good hints that the tomato you're looking at might be a good fit for your indoor growing adventures! I have found that cherry tomatoes are better suited to indoor growing than standard-sized tomatoes. A search for “cherry tomato” on DigTheDirt yields a lot of good varieties, but if you'd like to try standard tomatoes, keep an eye out for those keywords—dwarf and/or container plants are selected for growth in conditions that are less than optimal for standard tomatoes, so they are more likely to thrive indoors. This site has some information and a few tomato variety recommendations. If you end up buying plant starts instead, do the same research before you decide on a plant, and when you do buy it, check it thoroughly for pests, as should be done for any plant being brought into the home. I brought aphids and spider mites into my apartment because of my inattentiveness, and my tomatoes were not happy about that! A quick shower and a spray with neem or any of your preferred insect-treatment sprays (make certain it's okay to use on vegetables!) will take care of most insect pests, and it's a good precautionary measure.


Although I suggest checking out “dwarf” “container” tomatoes, I myself first tried Ace Bush and Cherokee Purple.



Folks, this was a ridiculous, unresearched decision. They both grew over nine feet tall in my living room (see?!), and I harvested maybe ten tomatoes from Ace (some below). And that was only after nearly 11 months of growth. I had much better success with the Red Cherry tomatoes that year, and this year, I've been pleased with Super Bush, a dwarf container variety I got from Renee's Garden (photo at top of post).



Growing Tomatoes


Start seed in a seed-starting tray or small pot, as you would if you were starting seed to plant out-of-doors. Bottom heat is nice to encourage germination and healthy growth, and placing the seedling directly under a fluorescent light will help keep it stubby and strong. Once the plant has two or three true leaves, pot it up incrementally until it's in anywhere from an eight-inch to 12-inch container. Growing most tomatoes in containers outdoors, the recommended container size is 18 inches—indoors, however, these plants do not usually reach their full growth potential, so a smaller pot is quite alright. My three cherry tomato plants did just fine together in an eight-inch pot, but Super Bush gets its own 10-inch pot. (Renee's Garden has good information on starting tomatoes from seed and potting the seedlings up.)


I use standard potting soil for my indoor tomatoes, but it is a good idea to incorporate some compost into the soil (worm castings or similar composted material would be excellent—these are high-nutrient-needing plants, and you want your crop to be as healthy as possible!). You can additionally use liquid fertilizer at quarter strength during regular waterings. I have been told by longtime container gardeners that top-dressing fertilizers such as Osmocote don't offer much benefit to container-grown plants, but I haven't really tested that myself.


Through the entire growth of your indoor tomato plant, it will need as much light and heat as you can offer it. A south-facing window is the bare minimum necessary, unless you have an excessive grow-light setup in your dwelling. My southeast-facing window gets anywhere from five to eight hours of direct sunlight each day, depending upon the season—but even with 24-7 supplemental lighting (fluorescent and/or incandescent grow lights), my tomato plants seem to prefer the limited natural light from the window, and the fluorescents irritated my neighbors on the other side of the building, so I ended up not using them.



If you're growing these during the winter, keep them away from open windows, drafty doors, or heat vents (standard advice for a lot of cold-sensitive houseplants, in fact). Also, don't allow the plant to actually touch the window in any significant way, because the radiant cold will make it unhappy.


Making Whoopie


Tomato flowers must be pollinated in order to set fruit. Not all plants in the world require pollination to make fruit, but tomatoes do—without pollination of the tomato flower, no tomato fruit will form. Outside, this is usually taken care of by bees: They flit by, grab some nectar, and pollen is released from the vibrations of the buzz-buzzing wings. Most indoor tomato growers would probably be averse to releasing a swarm of bees into their living room just to pollinate their tomato plant (but I don't discount that some of us would actually try it, at least once), so there are other ways you can do this.


Books and Google searches yield a lot of different methods: misting with a spray bottle, shaking the plant, using a paintbrush, and other tactics. I've tried just about everything, and none of those really seem to work. Don't bother. Grab an old electric toothbrush, electric razor or beard trimmer, or personal vibratory device and go at all the open tomato flowers whenever you have a chance. You should turn on your vibratory device and gently touch the grouping of flowers or the little branch right behind the flower. You should see a puff of pollen being released just as you touch the plant (I have a video of pollinating peppers and tomatoes using my beard trimmer on my blog). I usually do this before I leave for work and when I get home, whenever I remember to while the flowers are open, over the course of a few days, to make certain that my tomatoes are as pollinated as they can be. In a few weeks, the tomatoes will flesh out and ripen!




Outdoor tomato plants have a lot of foes to battle, including fungal, bacterial, and insect pests. Indoor tomato plants don't have to worry too much about most of them, especially the infamous Phytophthora infestans, also known as late blight, that pathogen that wiped out the potatoes in Ireland and caused a nationwide ruckus in 2009. But indoor tomatoes (any indoor plants, really) do have to watch out for spider mites in particular (but here's a good link with some basic information on the most common houseplant pests). Sometimes these tiny critters are an issue, and sometimes they aren't. In 2009, they had the run of my indoor tomato plants, building nice little homes in the leaves and making me go berserk. In 2010, the buggers didn't touch my tomatoes. I had the plant closer to the window (more light, more heat, more humidity, all of which help control spider mite populations) and right next to my lemon geranium (a lot of “lemon” plants are considered to be insect repellents)—one or the other of these might have contributed to the lack of spider mites this year, or maybe the crawlies just decided to leave my tomatoes alone for some reason, even though they are still killing my Alocasia “Polly” just two feet away.


Beyond different pest issues, indoor tomatoes do not grow the same as tomatoes that are in optimum conditions. Indoors, tomatoes are a little slower to mature and fruit, they are a bit leggy, they don't get as large as they would outside, the yield is significantly less, and the size of individual tomatoes can be smaller than they would be if grown outside. But, if a good variety is chosen and enough nutrient, heat, and light are provided, there's no reason why you can't have a reasonable haul, even in the middle of winter!


tomato, indoor, Cherry Tomatoes


I used trellis for my small tomato garden and the plants managed to cover it whole. Good thing it wasn't indoors :D
polbishop commented on 06/02/16
This is a very informative post, thank you so much for sharing your pollination technique! I recently moved into an urban high rise, miss gardening and am in the process of starting an organic edible indoor garden.
jDelaneyh commented on 03/09/12
Great post indoorgarden_er! We were growing tomato's in our store front's indoor garden and they took up an entire wall. It was like the tomato forest. Tomato's are an exciting and challenging plant to grow indoors and I greatly appreciate the insight and photos you posted here.
The Big Tomato commented on 01/28/11
FigTree, they DID take over my living space. A two- or three-foot-tall tomato plant is a lot more manageable. :D <br/> <br/>For longer-term growth, gardengirl, you&#x27;d want indeterminate tomatoes, of course. They&#x27;re trickier to grow indoors, but with excessive pruning, they might not get as crazy as mine did, and you might have some good harvests throughout the year! I haven&#x27;t tried Juliet, but I rooted a yellow pear cutting (and subsequently lost it after a weeklong hiking trip dried out my babies). Sungold cherry tomato is my absolute favourite, but unfortunately, those rooted cuttings died the same way. It&#x27;s a dangerous world over here!
indoorgarden_er commented on 12/08/10
I love your post! I have a few sprouting tomatoes in the garden from the summer crop and was considering digging them up and overwintering them inside. I had no idea you could grow tomatoes long term inside a house. Your picture of the tall plants made me smile and the how to on pollinating made me laugh out loud. Oh, the lengths we will go to in order to get good tomatoes! I totally understand! I had to help my cucumber plant get to work this summer. Have you ever tried growing yellow pear or Juliet tomatoes inside?
gardengirl commented on 12/06/10
Thanks for such a robust post about growing tomatoes indoors! My tomato crop this summer was pathetic, due to a colder start and an ill-paced vegetable bed... so I&#x27;ve been thinking about controlling the environment more with hydroponics... I especially love the tips on pollenating!! Thanks.
chief cultivator commented on 12/06/10
Wow! I honestly didn&#x27;t know that you could grow tomatoes indoor without a greenhouse. This is an inspiration! That one tomato plant that grew nine feet tall is insane... looks like it was taking over your living space :) <br/> <br/>Thanks for all the info.
FigTree commented on 12/06/10