In my last post, I mentioned that it’s important to select the correct container size for growing vegetables. In fact, I pointed out that the correct size is nearly always bigger than you think it should be. I think the common error of putting plants in pots too small for them is akin to the instinct that makes us plant them too close together in in-ground gardens. They are just so cute and little when we put them into the ground—how can they possibly turn into hulking monsters with thirsty and enormous root systems? Don’t be fooled! Size up your containers and make your plants happy. (HGIC has a handy set of guidelines.)
It’s not just the size in gallons that matters to successful container selection, though, as my next-door neighbor found out last year. She grows tomato plants in pots on her sunny patio, and has great success. In fact I would say gargantuan success—her plants are huge!
I’m not sure what she does to make the tomatoes grow so tall so fast, while mine are still about half the size in my community garden plot. Soil in pots does tend to be warmer in late spring when the ground temperatures are cool, and my plants catch up over time. Potting soil with plenty of fertilizer included gives plants a fast start, and regular doses of fertilizer keep growth chugging along. Fertilizers with a high percentage of nitrogen produce rampant leaf growth, so that may be part of the equation, though the nutrients must balance out over time since her plants produce plenty of fruit.
In any case, it’s been working out well for her. Until last year. Last summer we had several periods of high winds. The top-heavy tomato plants kept crashing over. In July our neighbors went on vacation and asked us to water their plants, but on the first morning I went over and found the tomatoes on the ground. I ended up creating an arrangement of string, stakes, and cinderblocks to keep them upright.
So, container volume isn’t the only consideration—shape matters as well. Containers that are higher than they are wide may not work well with plants that get very tall. My neighbor (who was very grateful for the emergency tomato intervention!) had basically two choices: get new containers (wider, heavier, with a lower center of gravity, like half-barrels), or grow shorter tomato plants.
Therefore, I have introduced her to the Dwarf Tomato Project, and will be growing seedlings for my own use and hers. These dwarf plants, bred for growing in containers, produce tomatoes with real heirloom flavor, but they stay short (heights vary, but most are under four feet). I only have a little experience with these varieties (I figured the Year of Container Gardening was a good time to get more) but like heirloom plants, they’re inconsistent in how many tomatoes they produce over a season; some are prolific and some stingy. So we’ll see how it goes. I’m trying three varieties: Uluru Ochre (which I’ve grown before), Rosella Purple, and Summer Sweet Gold. I’ll also get some full-size plants to mix things up, of course!
The other advantage to dwarf tomato plants is that you don’t need huge containers, but still—I’ll go with the largest ones I own. Other vegetables that grow best in bigger-than-you-think pots include squash (and its relatives like cucumbers and melons), potatoes and sweet potatoes. Size up for success! Also, look at seed catalogs for varieties intended for containers; they will be shorter with smaller root systems and may still be quite prolific while demanding less water. (But remember to water frequently nonetheless.)
Spring is coming, so have your containers ready!!
By Erica Smith, Montgomery County Master Gardener. Read more posts by Erica.
All photos by Erica Smith