Several years ago when I started growing tomatoes in containers on my roof, it was a bit of trial and error to get a system that worked right and there wasn’t a lot of information about it on the Internet.
I’m still surprised at how often there are misunderstandings on the subject.
The year before last I offered some of my extra tomato plants to a neighbor who she said she would be pleased to take four of them. A few months later she told me they weren’t doing well, and asked me what could be the problem. She said the tomatoes were too small, and not getting ripe. After talking about it some more, she took me over to the plants and then the answer was clear. She had put the four plants, all in a row, in a window sill planter with about five liters of dirt.
Okay, first of all tomatoes (and most other vegetables) are different from flowers in that they need enough dirt to grow full sized, and need full sun, or the plants just won’t be healthy. The other thing to keep in mind is that heirloom tomatoes are different from commercial varieties, in that many commercial varieties are bred to be small plants, perhaps even be grown in a hanging basket or whatever.
Nearly all heirloom tomato plants are very large! They often grow over two meters (six feet), and can weigh well in excess of 45kg (100+ pounds). They will also need some support, usually in the form of a bamboo or plastic stake. They will need enough dirt to hold the stake and the container will have to hold a plant this big and still be stable. Keep this in mind when you are thinking about a good container to buy.
I find the most important factor is volume of dirt. I use containers that hold 30 liters (7.3 US Gallons), and I find this is both the minimum but also an amount that usually works okay. More is obviously better, if possible.
For dirt I usually use a mix of homemade compost and peat moss or similar potting soil. Keep in mind most potting soil contains chemical fertilizers, which you don’t want if you are gardening organically and can affect the way your tomatoes grow, and you don’t need any fertilizer if you are using compost. I prefer using plain peat moss instead of potting soil, which is usually cheaper anyway. If you have it, 100% compost is the best, otherwise a mixture of at least 30% compost is probably good enough. Tomatoes don’t like to share their root space with other plants, so put each plant in its own container.
One of the most common pitfalls with tomatoes is over-fertilizing, which results in a bushy green plant with few tomatoes and well as other problems. I usually don’t add any fertilizer, and if you use at least 50% compost in the soil mix it is certainly not necessary. If you must, fertilize with fish emulsion or similar only once or twice, starting in August.
One of the biggest challenges with growing tomatoes in containers is keeping them watered. In the perfect world, tomatoes like to be watered in the evening then dry out during the following day. This wet/dry cycle is important for healthy plants. If the plants are too wet, the tomatoes will crack. If they are too dry (or you don’t have enough dirt) you will get Blossom End Rot (BER). With BER the ends of the tomatoes turn brown and rot. The more dirt you use in your container, the easier it will be to regulate the water.
I use a water timer and a drip water system. I begin by watering only in the evening, but during the hottest part of the summer I water twice per day. During periods of heavy rain, I turn the water off.
The plants will need some support, either in the form of a cage or a stake. I find the easiest is a stake, in which case it’s important not to tie the plant too tightly, because the plant will grow.
What can go wrong?
The most common problem is BER. This problem is caused because something is keeping the plant from absorbing the nutrients it needs. Some people suggest adding calcium to the soil as a way to prevent it, but I find a soil deficiency is rarely the true cause. Usually the problem is too small of a container or not enough water. It can also be caused because when the plant was young you tied it to its stake with a piece of wire that was too tight, and it grew to the point the plant was pinched off with it. Sometimes it can take a little detective work to find the cause of this problem.
The next common problem is splitting, which is caused by irregular or over watering. Sometimes you are just cursed by rain, and there isn’t much to be done about it. The best thing is to try to get as close to the wet/dry cycle I describe above.
Many diseases affect tomato plants, some are more serious than others. It’s very unlikely you will go through a season without encountering something. The best way to address most problems is with hygiene. If moldy or brown leaves appear, remove them. Try to keep plants separated with air space between them as much as possible. Don’t put any diseased plant material in your compost!
One of the most catastrophic tomato diseases is blight, a disease shared with potato plants and one that is becoming more common all over the world. This causes large black or grey blemishes to form on the plants and fruit, and the plants normally die within several days. There is nothing you can do once your plants become infected. Infection can usually be prevented by growing the plants in a greenhouse, if this is an option for you. The theory is that a blight infection can only take place if the plant is wet, so if you protect them from rain and are careful not to get the plants wet when you water them, you can prevent the infection in the first place. This is a highly contagious disease, and the spores can survive several years. It is best to destroy infected plants as quickly as possible.
‘Wilt’ diseases are sometimes also encountered. In this case the leaves of the plant will wilt, and the growth of the plant will be severely stunted. Since the wilt diseases are soil borne, you are not likely to have a problem with it spreading to other plants if all of your plants are in their own containers. Infected plants will normally produce some tomatoes. If you have problems with this disease, there are resistant varieties of tomatoes available, unfortunately these varieties don’t usually include heirlooms.
Very inormative Patrick. I’ve had BER last year from irregular watering as I’m often away weekends.
I suppose you’d have to be careful growing lots of tomatoes on the roof – what with the weight of the container, the dirt, water, and of course the crop. Ready made tom sauce as it crashes through the ceiling!
You’re right of course John, and I am a bit worried about that. This part of my roof was built as a roof terrace, with extra reinforcement. At the same time it is a 325 year old house, and does have it’s limits…
Thanks Patrick! I wonder how big my commercial varieties will get. Last year the cherries were fine in smaller containers (around 10 litre I guess?) but the roma got blossom end rot. I have to have a better solution for this year.
I just planted all my extra pepper plants into the window box as they were root bound and I don’t have my bigger pots yet! Hopefully it will tide them over until I get my pots in.
Very helpful, thanks. I have just started gardening, and had some success growing tomatoes in the garden, despite the dreaded blight. I plan to grow in pots next year.
Hi Ian, thanks for stopping by! Good luck with the the tomatoes next year.
Thanks for all of the help, this is by far the best guide on growing on pots I can find.
I am having huge problems at the moment with splitting. I am growing appolo’s, beef steak roma’s, and cherries.
Last year I grew in pots and watered morning and night with no problems. This year I have set my plants upto a timer 4 x a day and all tomatoes are continually splitting. Will try cutting the watering back to just nightly.
What are your thoughts on having trays at the bottom of the pot? I am starting to think this may be a bad idea as it does not let air up into the bottom of the pot. root rot?
Cheers
Hi Tony,
Thanks for the comment.
I think trays under the pots are okay, as long as they still dry out and aren’t sitting in a puddle of water all day. Some people may find a water tray is the only way they can keep them moist enough in a hot climate.
Good luck with the tomatoes!
I was recently told by a worker at Agway that to get truly good tasting “jersey” tomatoes that it’s better to add real garden soil to the the pots. If this is the case, what amount of each would you use?
Hi JC,
I would suggest something along the lines of one of these:
1/3 potting soil or peat moss
1/3 compost
1/3 garden soil
—
1/2 compost
1/2 garden soil
—
1/2 potting soil or peat moss
1/2 garden soil
fertilizer appropriate for tomatoes
—
Unless your garden soil is very rich in organic material, you will need some organic material from either compost, peat moss or potting soil.
You will need some source of nutrients, either compost or other fertilizer.
The rest can be garden soil.
Good luck!
Thanks a lot Patrick.
Couple of questions please. What about whiskey half barrels and this Topsy Turvey thing?????
Hi SP,
Half barrels might be a bit on the large side. If what you have is around 25 gallons, this is about 3 times what most heirloom tomatoes need. You could always give it a try with more than one plant per barrel, but most tomatoes prefer to have their own root space.
I understand the Topsy Turvey thing works fine, but there are lots of plans on the Internet for building your own for much less money.
Hi Patrick, lots of good info here from practical experience. That seems hard to find on the net. Growing in pots/containers is pretty new to me and this is good stuff. Thanks for posting your experiences!
Just found your site — I’m one of the Topsy Turvy people (my 4-year-old wanted to try an experiment). 🙂 The tomatoes were doing fantastic until yesterday, when I mistakenly fertilized them an hour after my husband did. 🙁 Today, the stems and leaves are all wilty. Did I kill it?? I’m really upset — this is the first time I’ve been able to grow healthy tomatoes.
Hi Emily,
I’m afraid I can’t be of much help. I don’t use fertilizer like that, only fish emulsion very occasionally, and not usually on tomatoes. I don’t have any advice to offer. I hope it works out okay!
It looks like they’re reviving (this is what happens when you send panicky emails) — but I’m not using fertilizer anymore. I must have constipated them. 😉 Thanks!!
I am going to grow some heirlooms this summer, it’s my first time growing them in pots. I saw where you said you use peat moss and compost, which is the best ratio of compost to moss and is there a specific compost type (like chicken or cow) if you don’t have your own?
Hi Si,
Compost is compost, and it shouldn’t matter much what kind — as long as it’s fully decomposed. If it’s made with animal manure, it’s very important to make sure all of the fresh manure is gone, and this can take as long as 2 years. It might be better to use compost that’s been made with only plants, if it’s available.
You can use anywhere between 25-100% compost, depending on what you have available. Normally the more compost the better, but if you’re unsure of the quality of your compost it may be better to use less.
Good luck! Nothing beats the taste of home grown tomatoes!
I quit growing tomatoes in containers a few years ago due to the difficulty of keeping the right amount of water. Well this year I have gotten some 25 gallon containers and I am going to try again but with a drip system on a timer. My question is how many gallons of water should I set the drip system on. I am using potting soil in FULL sun and I expect it to dry quickly. I am thinking a gallon per day but I am only guessing. I am growing only heirlooms. I have read everything about container growing I can find but have found little to nothing about watering.
Terry
Hi Terry,
Ideally your plants will nearly dry out, before you water them again. Early morning is the best time to water.
With this in mind, you just need to experiment, and check frequently to make sure they are still getting the right amount of water. You may find watering only once a day is not enough.
1 gallon of water per day seems like too much to me. I would start with a half gallon, and adjust it as necessary. I think I use about a quart myself, but my drip water system doesn’t measure the water that way.
Tomatoes are one of the most common vegetables all over the world. They are quickly growing plants and are favorite among most amateur gardeners so as me.
I will start to grow tomatoes in my farm and now learning watever i can about them, thanks for information. I also
found another good site about tomatoes and so many other methods of agriculturing, i recommend you to take a look.
http://agricultureguide.org/
Hi Caglar,
Thanks for the comment. I agree, Agriculture Guide is a great site! I sometimes read it too. Thanks for leaving the link.
Thanks for posting this. But I have to say, it’s tough to figure out who to trust.
I’m a new container gardener and am having a helluva time trying to figure out this watering schedule. I don’t have the luxury of being able to install a drip system.
Last year I believe my problem was overwatering. I’m in Los Angeles where the summers can get pretty hot. I was watering tomatoes in 5 gallon containers once a day and noticed both my plants were developing yellow leaves around the base and moving up the plant. The nursery told me to scale back to twice a week, which I think helped, but they never really recovered. The also recommended I add some Sea Kelp extract to the water, which I did and that did help.
This year I met an old woman at a garden show and she said I should water the tomatoes once a day for the first week, then once a week. I’m about a month into this and all my tomatoes leaves are curling in and the plant is flowering. I called a nursery yesterday and they said every other day in the morning. I’ve also heard the “finger one inch into the dirt” method, and if it’s dry, water.
I guess I’ll try your “every day in the evening recommendation,” logically it seems to make the most sense when considering the wet/dry cycle. Then again, I don’t know if logic has anything to do with this.
Thanks
Greg
PS- I’m also growing strawberries, bell peppers, green beans and some herbs, all in separate containers, if you have any recommendations.
Hi Greg,
Good luck, and thanks for the comment. If the tomatoes get too much water or are watered irregularly they will split, and if they are too dry they will develop blossom end rot.
Peppers are about the same as tomatoes.
For the other things, it’s less important, just make sure they get enough water.
Lots of good info here. I am experiencing the same problems that Greg has mentioned in that a couple of my plants have lower leaves turning yellow and moving up the plant. I went away for a long weekend and thought I would water them extra before I left and came back to a couple of plants that are looking pathetic. I used moisture control miracle grow potting soil and have also been using a mircle grow hose feeder. I am noticing that I have the very large and bushy plants that have been mentioned with what I consider to be less than productive plants (approx 6-7 tomatoes per plant). Am I over watering and fertilizing possibly?
Hi Glenn,
Tomatoes are very sensitive to getting too much fertilizer, and what you describe a bushy green plant without many tomatoes fits in well with this. It wouldn’t surprise me if your other problems are from this too.
Regardless of the brand, commercial potting soil always has fertilizer in it. You probably don’t need any more than this. I use peat moss (potting soil without fertilizer) mixed with compost which has organic nutrients in it, and this works well. You might add a little fertilizer in August or so, well after most of the fruit has set, but this is optional. It’s best to add the fertilizer only once during the growing season.
It’s worth mentioning a few yellow leaves on tomatoes are normal, and there may be nothing wrong with this.
My tomatoes are in 12 inch pots in a greenhouse each standing on a tray. I’ve always been advised (with mature plants) to water into the tray only, so they have to suck the water up,and the top of the soil is completely dry. I’ve found that if I allow the tray to dry out, I get some blossom end rot, so this year I’ve tried to always have some water in the tray on the basis that most of the soil above is dry. I’ve had pretty good results so far this year, but have just discovered some blossom end rot (not too much but maybe it’s going to get worse). Am I completely wrong or do other people do it this way?
Ian
Hi Ian,
I sometimes water tomatoes from the bottom, and I don’t think there’s anything wrong with this per se. The real problem is tomatoes hate having ‘wet feet’, so you should make sure they aren’t sitting in a puddle of water. Sitting in a puddle of water is more likely to cause splitting than BER, in my opinion.
BER is a general sign of stressed plants, and in your case I think it’s probably the size of your pots which seem pretty small to me. It’s not necessarily this, it depends on the variety and if you’re experienced in growing tomatoes in this size pot, then you should follow your own experiences.
If it’s not the size of the pot, then you simply have to have a look around your plants and see what else may be stressing them.
I am really new at this. My tomato plant is in a 12 inch pot and the plant is about 28 inches above the pot with nice tomatoes on it, but the lower leaves are turning yellow. I plan to water it in the mornings from now on. I’d like to put it into a larger pot, but will I damage the plant by transplanting it now?
Hi Pat,
No, that’s no problem, tomatoes don’t mind being transplanted at all and if you take reasonable care you are unlikely to damage the plant.
Tomatoes are a little unusual in that they can grow roots on any part of the plant. Since tomatoes often have a weak root system, during transplanting they will benefit from being planted deeper in their new location. This sort of ‘shocks’ them into developing stronger roots.
If your plant now is 28 inches above the pot, you might for example try to plant it so it’s only 23-24 inches above the ground in the new pot, covering the bottom 5 inches or so with dirt. It’s okay if the existing roots are all the way at the bottom of the new pot.
Good luck!
My plants look great but the tomatoe is very small and ripening before they get large
Hi Dawn,
With so little information about the type of tomato and how you are growing it, I’m afraid I can’t be much help.
The three most common problems are too much fertilizer, too small of a container and irregular watering. You might think about these things. Good luck!
Hi Patrick,
I transplanted my tomato into a larger pot and it seemed to be doing great with the tomatoes growing and ripening nice, but I just realized the new buds are turning brown and falling off, so no new tomatoes….boo hoo. Now what do you suggest, could it be too much water maybe? Tks much for helping me here.
Hi Pat,
Sorry for the slow reply. Over-fertilizing is a very common mistake, and can cause this problem. If this is the case, it’s going to be hard to solve, because you can’t remove fertilizer.
Otherwise, it’s probably not too serious. Lots of things can cause this problem, and probably nothing is wrong. It might be your plant is too laden with fruit, and it’s not setting more for this reason. Warm weather can cause this. It might be the roots are filling in their new space and the plant is putting resources into this.
It may be a lack of insects or wind, either of which is needed to pollinate the flowers. In particular if you are growing this indoors, pollination can be an issue and you can hand pollinate by gently shaking the plants to help the pollen move around in the flowers.
I hope this helps.
Thanks much Patrick, but I guess I just have to wait and see what happens. The plant is inside, and we have plenty of wind. The potting soil I had used to replant was the type with fertilizer, the only kind we had at the time, so perhaps that is it. I’ll cross my fingers and be a little patient, see what happens. I’ve acquired a 2nd tomato plant and it has a few white flies. I’ve never found anything to work on my plants for those, pesky things.
Thanks for the great info Patrick. I’m a firs time tomato grower. I was really enthusiastic from the beginning, especially when the plant started to show flowers and subsequent “small fruits”, but after a day I noticed that the fertilized flowers which were now tiny tomatoes had gone all black and were falling off. Is this BER? I use an organic fertilizer and only fertilized the potting soil two times after I transplanted it to the pot.
Any tips would be very highly appreciated
Hi Hasan,
Very strange! No, I don’t think it’s BER. This is normally on larger tomatoes close to the time they get ripe, and even then it’s usually only a spot on the end of the tomato.
My computer tells me you are in Malaysia, tropical with cool nights and a daytime temperature around 27C almost year round. Sounds great! It should be perfect weather for tomatoes, and I can’t think of any special diseases you might have.
In general, most tomato diseases are related to too much moisture on the leaves and plant itself, so it’s best to protect it from rain if you can, maybe with a piece of plastic. Otherwise, you might have a pot that’s too small and you might be using too much fertilizer.
Good luck!
Patrick, Thanks for the great information. I am going to try my hand at growing some tomatoes in containers this year. Over the past few years I have had a problem with growing them in my yard. They start off great. Grow quickly and develop a lot of fruit. However, after about 3 weeks the plants, that are about 5 feet tall by then, start having their leaves turn yellow. flowers stop developing and the vines start to die. I have gotten soil samples, everything looks good there. I am not sure what the problem is. I live in the Atlanta area and the summers get quite warm, but I would not think that is the issue. I have planted in different parts of the yard, I have put down compost, but same results. Do you have any ideas? Thanks!!!
Hi Will,
I think I’ve probably said this to other people above, but the most common pitfall with tomatoes is too much fertilizer. If the browning of the leaves occurs anytime near when you add fertilizer, I would suspect this.
Otherwise the last few years there’s been a serious tomato and potato disease in the US called late blight, and it might be this. The leaves don’t normally turn brown, but rather black, and the vines get very characteristic black splotches on them. If your plants get this, they will die very quickly and there’s not much you can do about it. If this is your problem, growing them indoors or in a greenhouse will help slow the disease down a bit.
Beyond this I don’t know, but trying them in pots seems like a reasonable thing to do.
Thanks Patrick for the advise. I’ll bet the fertilizer is the problem. I will not use any this year. But I should use compost, whether I plant in the ground or in pots, is that correct? Thanks again. And if so, should I top off the plants with more compost midway through the growing season?
Hi Will,
The more compost the better, regardless of pots or ground. If you have enough to begin with you don’t need to add any later, but you can if you want.
I don’t usually use fertilizer myself, and it’s not usually needed, but you can use a little midway through the season if you want. Just make sure it’s not too strong, and use it sparingly.
If I use anything it’s fish emulsion or something else very mild. Beware this can give your tomatoes a fishy taste. It’s best to fertilize late enough that the fruit has already set, because over-fertilizing can cause fruit set problems.
What do you suggest if a person does not have compost. Can a person buy compost somewhere. Or what else would you suggest? We are just getting started with gardening and growing in barrels.
Thanks,
Jodi
Hi Jodi,
Everytime I’ve bought compost I’ve been disappointed. It’s not impossible to do, only most of the time it’s of very poor quality. Poor quality compost is sometimes okay for the garden, because it gets mixed in with everything else, but for potted plants it’s best to only use compost you know is of good quality. If you do buy it from a store, make sure the label specifies it was made from ‘known materials’, for example wood chips or other garden waste.
If you don’t buy or have your own homemade compost, then I think you just have to use commercial potting soil. Your plants won’t be organic, because commercial potting soil contains chemical fertilizer, but they will probably grow okay.
It’s also possible to buy plain peat moss and mix your own fertilizer into it, but this is tricky, and it’s easy to get the wrong proportions. I would advise starting with purchased premixed potting soil.
Purchased potting soil normally only has enough nutrients for a few months, so it might be necessary to add more fertilizer later.
It’s very easy to kill or damage your plants with too much fertilizer, so go very easy with it. Never use more than it says on the label, and I usually only use about half the recommended dosage. Also, for tomatoes it’s best to only add fertilizer once, usually after you have harvested the first round and the fruits have set for the next round, about August or so.
I bought a 10 inch potted tomato plant with 9 tomatoes on it. My father used to fertilize his garden of tomatoes with coffee grounds and broken up egg shells and had great results. Can I use this fertilizer with potted tomatoes? I have learned much from your sight. Thank you.
Hi Liz,
Things like coffee grounds and egg shells need to break down a bit before they can be used by a plant. I don’t think there’s enough time in the season for this in a potted plant.
In the garden, what’s left over breaks down during the winter, generally enriches the soil, and can be used by plants the following year. With a potted plant, I think the coffee grounds and egg shells will just sit on top and not do anything.
What you can do is make your own home made compost, add the coffee grounds and egg shells to that, then use this the following year for your tomatoes.
Good luck!
some expert suggests for soil betterment add nitrogen, phosphorus and potassium ?/
Hi Ejaz,
Thanks for the comment, and good question.
Nitrogen, phosphorus and potassium (NPK) are like vitamins for your plants, and saying they improve the soil is like saying taking a vitamin pill with dinner makes it more nutritious. Adding fertilizer doesn’t improve the soil, unless these things are missing in the first place. Mostly it’s better to think about the quality and health of soil, than what vitamins it contains.
It is true that growing any plant in a container is sort of an artificial environment, and the limitations of root space may mean it needs a little fertilizer. If you use enough compost initially, you probably don’t need to add much if any fertilizer. In any case fertilizer can interfere with fruit set, so it’s best to use it after the tomatoes are already developing on the plant. It’s also very easy to kill or damage a tomato plant with fertilizer, so choose something very weak and be careful not to use too much.
It’s much more common to have problems with too much fertilizer than with too little. Remember once you add the fertilizer, you can never remove it.
Good luck!