You might want to check over on the Growing Tomatoes forum here as there are many discussions there about this question.

Some sq. foot gardening users plant in 1 sq. foot and prune the plant to a single stem.

Dave

Here is a link that might be useful: Tomato forum

You can certainly bump cages up against each other, but at some point, squeezing in too many plants will decrease your production. Better to grow fewer plants with enough room for the roots to grow more and limit their access to nutrients (and sunlight).

I typically double up, plant two plants together in the spot where one should grow, 2 ft apart in rows 3 feet apart, I can get 16 plants in about 60 square feet, these are paste tomatoes so not overly large plants, I use 2x2x8 wooden stakes and lots of sissal twine to tie them up. they are heave feeders so I give them alot of grow juice until they start to flower, never had issues with yield, but then again san marzano are prolific.

Closest I have done, I would say, 16 inches. Many 18" - 24". But as Dave said, you have to do a lot of pruning , CONSTANTLY. and have to stake them. Cage is not practical with 16 to 18" spacing.

Another option/method I will try this year is: PLANTING 2 PER HILL ( about 6" apart) and space hills about 24" to 30".) Again, you have to limit number of stem to 2 per plant. Max 3. This can work better for determinats.

Agree with above posters. Just wanted to point out that every Cherry tomato I have ever grown was as big as the largest beefsteak plants.

If you want smaller plants, you could try Rutgers or Celebrity. And of course, the ones that are bred specifically for pots like Bush Goliath, etc. Those you can plant closer together.

Donna makes a good point. Depending on what varieties of cherry tomatoes you have they could easily be your biggest plants by far, bigger than Brandywines easily. You really need to know the growth patterns of your specific varieties.

By the way, just because I mentioned the 1 sq. foot method used by Sq. foot gardeners doesn't mean I recommend it. Personally I don't agree with pruning tomato plants so I seldom plant indeterminate varieties closer than 3' square. 2' square can work if space is really limited but it will turn into a jungle without lots of careful pruning - and that costs you production.

Dave

I've planted tomatoes sfg-style for the past 2 years with really good results. I usually plant about 12 plants in about 10 sq-ft plus two pots on my patio. The pots get staked and do okay, but not as well as the tomatoes in the sfg (I'm bad at watering!). I train the tomatoes in the sfg to 2- 5'wide trellises and prune them to a single stem. I also trim away the lower leaves as the tomatoes grow to keep them away from the dirt. **I always intend to do 4 tomatoes on each 5' trellis to give them a bit more room, but then I end up with too many seedlings and can't bear to toss them out.

I get enough tomatoes to keep my Italian food-loving family in tomatoes all summer and can enough tomatoes to last us at least half-way through winter. I like that I can look down the row and easily see if any tomatoes are getting ripe, I remember my mom's determinate tomatoes in cages always being a mess of leaves and we'd end up missing a bunch of tomatoes because we didn't see them in the mess of leaves and they'd end up wasted. Not to mention the heavy plants toppling over the cages by summer's end!

*the trellising/sfg method only works with indeterminate varieties, you can't train a determinate/bush-type tomato to a small space*

I've never done SFG.
The cherries I grow are sungolds. VERY sweet and VERY prolific! not good (IMHO) for sauce. I have not had much luck with brandywine. They only produce maybe a dozen maters if that! The romas are good for sauce (and salads in a pinch), but you aren't going to get much sauce off of one trimmed plant!
In the future, you might look into a community garden for more space. My tomato area is about 4x8 and I get 5-6 full sized tomato plants in there and get enough sauce for about 6 months + slicing and cherry tomatoes.
If you have a sunny yard, you could also look into planting in containers.
If it were up to me, only having room for 2 plants, I would choose the best salad or slicing tomato (IMHO purple Cheroke) and a cherry like sungold.
If you're hell bent on making sauce you can go to a farm stand and buy in bulk. Nancy

I am not a SF gardener but I follow a tight regiment space wise. For example , in a 3' by 6'( 18 sf) raised bed I plant 8 plants. That is 2.25 sf per plant. The soil is a good 16" deep. So each plant is getting 16 gallons of soil per plant. That is plenty of root space.

Your productivity will scale with the space you provide. So there is no wrong number. I typically plant cherries eight inches apart on a trellis, and they thrive. They all get over eight feet long. Two plants in a 3.75x1.75 feet sounds real easy. They won't get in each others way.

Cherries are my favorite and as long as you've caged them, given a healthy amount of compost, and anticipate that they WILL be rambunctious growers overflowing the cages, there is no problem. I have used cages and trellis netting for a variety of indeterminate tomatoes and had no problems.

Your productivity will scale with the space you provide

^^^^^^^^^^^^^^^
I don't think so,necessarily.
Productivity comes from HOW you care for your tomato plant :
-- Nutrient,
---Moisture
-- Right amount of sun.
other growing conditions.

It does not matter if the roots are in ONE cubic ft or 10 cubic ft of soil. All the roots need is to draw nutrients from the soil around them . Now, if your soil is poor, they will have to expand, searching for food. In reach fertile soil it is not the case. Soil is just a medium as water is in hydroponic system.

Most of the spacing requirement is to accommodate the top foliage.

JMO

"Productivity comes from HOW you care for your tomato plant"

Well of course. But the question was about spacing. So all other things being equal, productivity will depend on space. If you have two plants, and only a tiny place to put them, put them both in. Better than just tossing one. You'll get the same productivity as you'd get with one, but you'd have some insurance if something happened to one of the plants.

The spacing requirement is more than about top foliage. If you have competing root systems, you won't do as well as if you didn't.

In my opinion if you plant 4 tomato plants on 3X3 area, you sure get less tomatoes then if you plant 4 of them on 9X9, but SURE more then if you plant just one on 3X3 area . I usually plant 16 tomatoes on 12X4 bed one year and 18-20 on 23X3 another year.

I think that's right. The issue is at what spacing root systems start to compete. But once you get below that spacing, the productivity will not depend on how many plants you wedge in. They'll all behave just as shoots off a main stem. I agree that a three-foot separation of full-sized tomatoes is about the minimum to avoid any root competition, but it will depend on the soil properties. That being said, if you plant them more densely, you won't increase (or reduce) productivity from that bed, but you'll have some insurance against bad things happening to individual plants.

I have a 3x7 area for my full-sized tomatoes, which I'm planting in a heritage variety that I collected seeds from last year. The seeds were free, and so were the seedlings. I put six plants in that space. I have no illusions that I'm going to get six plants worth of tomatoes there, but I have some confidence that if I lose a few plants, I'll still be good to go. If I were buying plants, I sure wouldn't have bought six.

I grew super sweet 100 cherry last year and it was a monster of a plant, much bigger than my three others (early girl, brandywine, and big beef). Good producer and tasty fruit, but I'm thinking of trying some other cherry toms this year.

I grew four plants last year in a bed that was 6' by 15" and supported via a florida weave. I'm trying to do some rotation this year, so I'm going to plant two toms in my 3'x1' bed and weave again, and then try some others in 1 square foot doing a pruning to one, maybe two stems and trying ladder type supports. I'm also thinking of trying a dwarf cherry or two in a hanging basket to see how that works out.

I'm very sure that planting a tomato in 1x1' space and pruning will be at the cost of production, but I'd like to try a few more varieties and don't have a ton of space. Plus I do like to experiment and work out what my best use of space is. If it's a bust, there's always next year ;)

So I have planted 1 per foot pruned to 1 or 2 vines per plant. Yes you lose production per plant, but you gain production per sqft. We had so many tomatoes and healthy plants. We pruned the leaves up to the tomatoes as they ripened and were picked. No diseases except in a bed that has been consistently a problem for years... Last year I planted in the ground at 1 per 4 ft, no pruning and had very few toms. So I think the people saying nutrient availability and care off the plant are more important than spacing are correct and I firmly believe pruned plants in small spaces can produce just as much as 1 large plant. We had cherries, brandy wines, beefsteak and green zebra. The only ones I had to pull were the Amish paste from the problem bed which I e decided to just not plant toms in anymore.

And here's the only pic I can find of them grown. Mind you we did this in 4 different beds. So it wasn't just luck. But they did very well planted at 1 per sqft. Very healthy and productive.

Well, this question wasn't about nutrient availability. It was about spacing. No question that if you plant tomatoes in, say, washed sand, you won't get any tomatoes at all, no matter how far apart you plant them. It's also going to depend on weather conditions and disease, and so the particular year. So the question is this - if you had two patches, with the same nutrients and soil properties, with the same weather conditions in the same year, how would the productivity depend on spacing?

I'm suspecting that the productivity *per plant* would be constant for spacings larger than 2 feet, and would decline when the plants get closer than 2 feet. By the same rule, for spacings larger than 2 feet, the productivity *per unit area* would decline as the spacing got larger, but for spacings smaller than 2 feet the productivity *per unit area* would stay the same. I dunno, call it 3 instead of 2?

So if I put sixteen plants in a square yard, I'd get the same number of tomatoes as I would if I had put one plant there. Of course, if I had one plant there and accidentally stepped on one, I'd get none. If I had sixteen plants there and accidentally stepped on one, I could expect my productivity to stay the same.

I get my hybrid cherries in 6-packs, and I have two 6-foot long trellises devoted to those cherries. So in principle, I could get one six pack, but I'd better not step on any. So I get two packs, and plant them closer than I need to. No sweat. I still get two trellises full of cherries.

One foot apart in a double row one foot apart. These were determinate plants. They were suppose to be a double tow one foot apart with two feet between plants. The family got my directions mixed up, but I didn't have the heart to tell them.

So I have planted 1 per foot pruned to 1 or 2 vines per plant. Yes you lose production per plant, but you gain production per sqft.
^^^^^^^^^^^^^^^^^^^^
That is a good point : PRODUCTIVITY PER SQUARE FOOT.

Tomato root are not very .aggressive. The roots mostly grow in a cylinder of about ONE foot diameter. Maybe a little more.

This is a typical double ball root system.

Look at this picture:

Yes, I figured I was being generous with 2-3 feet spacing. Of course, that corresponds to a root ball diameter of 1-1.5 feet. I've heard that, at least grown from seed, tomatoes have a pretty stout tap-root, which is what I think I'm seeing in your picture.

Seysonn, just curious, do you plant yours deeply? It looks like the original rootball on the bottom and the new roots that filled in from the stem after planting towards the top.

If that's the case, your photo is also a great example of why you should plant them deep to get all those roots. :)