This year will be my first attempt at growing tomatoes in a raised bed. Past tries, using pots or just the ground, have failed miserably.
My bed is 12” high x 71” wide x 35” deep, or 17 cubic feet.
I assume I’ll need a special vegetable growing mixture. But I don’t have to fill the entire space with that, do I? From my limited reading it looks like I need just 3 inches of the stuff up top.
If this is correct, what goes in the bottom 9 inches? Just regular soil?
Any recommendations for a specific brand, plus any other advice, is welcome.
A primary concern with a raised soil bed will be water. It will tend to dry out more quickly than the surrounding ground. So you’ll want to monitor moisture closely.
What went wrong when you grew the plants in the ground?
Regular soil mix (soil, perlite, coconut coir or sphagnum) below. Make sure the bed drains. Raised beds can be planted more closely, but leave room for tomatoes to spread out a bit. Some people put down a red or black plastic mulch with Xs cut in to plant the starts. Fertilize as directed. I usually throw a fish fertilizer in the hole and cover it with an inch of soil. I set a start in with a Wall o’ Water, then when it’s warm enough, replace that with a tomato cage. I usually pop in water-collecting funnels so I can water at the base as well as using overhead irrigation.
My suspicion is this is insufficient fertilizer, and/or insufficient sunlight. If they’re getting lots of sun and sufficient water but don’t produce, it’s most likely low nutrients in the soil/planting medium. In my raised bed I used a lot of potting mix for the top several inches, and the first year had an amazing crop. Much less in the second, because the pre-mixed fertilizer in the mix had been consumed. I tried using water-soluble fertilizer added to the water periodically, but have found that mixing granular fertilizer in the bed before transplanting is gets better results.
Possible. Another possibility is overly high nutrients in the soil/planting medium. Some plants, including tomatoes, won’t fruit if they’re getting too much nitrogen, because they go heavily to vegetative growth instead.
Yep- if you give them adequate fertilizer, lots of sun, and the right amount of water, you should do ok. That’s with the caveat that they really don’t love super-hot weather, nor particularly cool weather. 70s-80s is pretty much optimal temperature.
Fertilizer-wise, you don’t want high relative nitrogen. You can tell by looking at the fertilizer analysis- it’s listed as Nitrogen - Phosphorus - Potassium, or “NPK”. According to the University of Missouri, the best fertilizer ratios are 8-32-16 and 6-24-24, which can also be expressed as 1-4-2 or 1-4-4. Or really, any analysis with those ratios or something close is good. So if you could find something like 3-12-12, you’d be fine. Penn State recommends 1-1-1 until flowering, and then a high potassium fertilizer after that- they say they’ve been using a 1-5-10 fertilizer.
Tomatoes are heavy feeders though; follow the directions on the package for frequency. They also use a lot of water, so keeping them watered is very important.
A cheapo hose timer and a hose-end drip setup is probably best. My guess would be that a 1 GPH dripper run a couple times a week right next to the plant is great, unless it’s really hot, in which case I’d do it every other day.
That’s a point – most tomato varieties won’t set fruit if the nights are too hot. What amounts to “too hot” depends on the variety; but generally night temperatures need to drop below 70ºF, and day temperatures not to stay too long above 85ºF. If your weather runs hotter than that, you need a variety bred for that.
What variety were the plants, do you know? and where did you get them?
You also want a soil test first, on whatever soil you’re growing them in. It may already be too high in something you’re considering putting on.
Tomatoes are fussy about temperature. Make sure the soil is at 50F or above before planting. They thrive between 55F and 85F. Also, use starters, not seeds, and pick something that will actually ripen during your growing season. We used to plant Sweet Millions along with a medium-sized tomato in Oregon.
I’ve got raised beds in my vegetable garden - the natural topsoil is quite thin and overlays chalky marl; they are filled with sifted topsoil, but we add a lot of compost - last year I spread a couple of tons of well-rotted stable manure on them (we asked at a local stable and they said we were welcome to take as much as we liked, if we dug it ourselves from the heap); this year, we had enough of our own compost from several composting bins for vegetable trimmings, lawn clippings, shredded prunings, etc. I just spread the compost over the top of the existing soil, ideally in autumn, and let the worms mix it in, so there is minimal digging to be done.
Adding organic matter to the soil like this helps to create a naturally fertile soil that doesn’t really need any artificial feeding, and it also helps the soil to hang on to moisture. As the various soil organisms consume the organic matter and break it down, they excrete plant food.
I grew tomatoes in the greenhouse in grow bags last year, but other vegetables outdoors in the raised beds all did very well - for plants that need regular watering, I sink a flowerpot into the soil near them and water into the pot - it ensures the water goes near the roots and doesn’t just run off the surface.
South Texas raised bed newbie “farmer” here. Last year we built above ground beds using galvanized troughs. Jalapenos and bell peppers did ok. My cherry tomatoes did very well. I only had a couple of big tomato plants, and they did ok, but the damn stinkbugs kept ruining them! I watered almost daily because it was hot as hell. I gave up by July because I couldn’t keep up.
Does anybody have a stinkbug preventer? I was using diluted soapy water, but I don’t think it helped much.
This year we’re planting this weekend or next weekend, and setting up some shade cloth by April. And I will feed more regularly.
Even then, the hot weather varieties poop out with daytime temps in the low-mid 90s. Great for say… western North Carolina, but not enough for Texas.
In a lot of ways, when you grow them is as important as any other consideration. Here (Texas), they’re a spring or a late fall crop- ours are started indoors and about 8" high by the time we’ll be planting them outside in another couple of weeks. They’ll be tapped out by about Juneteenth- the plants may still be alive, but they’ll be wracked with early blight (which seems to blow in the air here), and it’ll be too hot by then.
Why? Starting your tomatoes from seed is an extra step, true, and may require a plant light; but it’s not that hard, a lot of people think it’s fun, and expands your variety choices quite a lot.
Or do you mean set out transplants, not direct seed them straight into the garden beds? That I agree with; at least, in most climates. I’ve never lived anywhere where direct seeding tomatoes outdoors would have been a good idea, so I don’t know whether it works in some places.
I don’t know whether interplanting marigolds will discourage stinkbugs; but marigolds do seem to keep tomato hornworms away.
To add to good suggestions already made (assuring full sun or close to it, adequate water, regular feeding that doesn’t overdo the “N” portion of NPK fertilizer), I suggest tilling or at least breaking up the soil underneath the raised bed, especially if it’s clay-based or otherwise has less than good tilth. Tomato roots will quickly extend a foot down (particularly if planted somewhat deeply, which is desirable if plants are on the tall and elongated side) and will not appreciate inability to readily penetrate underlying hard-packed soil.
Raised beds both warm up and dry out more quickly than surrounding soil. Mulching will be helpful in keeping soil cooler during hot summer weather and slowing evaporation of moisture.
I’m growing about a half-dozen varieties of tomato this year including heirlooms that are difficult or impossible to find unless you grow from seed. My mainstay is a large grape-type tomato, “Juliet”, a great producer which holds well on plants and has good taste.
I followed all the conventional wisdom listed here, and my tomatoes in open-bottomed raised beds grew well for years. Until they didn’t.
I couldn’t figure out what had changed, until I pulled out the sickly plants and started to dig in the soil. I found that roots from some silver birches had slowly trekked over from about fifteen or twenty feet away and infiltrated the raised beds from beneath. The planting soil had become a firm, impenetrable nest of birch roots, and the trees were sucking all the nutrients and water away from the tomatoes. No wonder the silver birch nearest the raised beds was twice as fat and healthy as the others!
We couldn’t fight the silver birch roots, so we eventually had to have the raised beds removed. You should have heard the landscapers cursing as they hacked and chopped away at the tangle of roots. Silver birches are bastards.