Grow bags for tomatoes? Nope.


I wanted the title to this blog post to be: “Why grow bags are not the best choice for growing tomatoes.”
I spent the past few years experimenting with the best ways to grow tomatoes.

I have grown tomatoes in raised beds, grow bags, plastic containers, and ground level garden areas. I grow indeterminate tomato varieties, so nothing I write here today is about my experiences growing determinate varieties. Not sure that is relevant, but I wanted to declare that up front.

Last year was an AHA! growing season for me because I discovered what I consider one the most important elements necessary for growing delicious tomatoes that do not crack: steady moisture levels.

I want to specifically address why I think grow bags are not a good choice for growing tomatoes.

I experimented with grow bags in different locations for two years. My grow bags are homemade and sewn from inexpensive landscape fabric. The grow bags that I placed in a warm, sunny location in my yard dried out very quickly. They needed daily watering, and even dried out too much during the day if temperatures were in the 80s.

Moskovich tomatoes ripening. These never cracked. Notice the moist soil. I never watered this side of the raised bed.

Moskovich tomatoes ripening. These never cracked. The occasional rain and spring below kept the soil consistently moist.

Last season, I planted my tomatoes in a variety of locations, but the one location where I had the healthiest tomatoes with no cracking at all was a raised bed in my backyard garden located directly above where a spring keeps the soil very moist. It wasn’t muddy, but the soil never dried out. The tomatoes that I grew in my front garden and in grow bags all had some cracking. The small cherry tomatoes in my front garden cracked the worst.
These tomatoes all cracked right before ripening due to dramatic soil moisture level changes.

These tomatoes all cracked right before ripening due to dramatic soil moisture level changes.

Tomatoes seem to do best with steady soil moisture levels. Dramatic changes in soil moisture stresses the plants which can result in diseases, etc. and can cause cracking. Cracking is bad because tomatoes are exposed to insects and can rot before ripening completely.

When tomatoes are ripening, the skin becomes softer and more delicate. Soil that dries out between waterings or doesn’t remain fairly moist means there is a quick uptake of moisture and water flows into the fruit causing cracking.

I did not get a single yellow pear cherry tomato last year that wasn’t cracked which means that the crop was mostly a loss. Even the red cherry tomatoes I grew cracked last year.

My recommendations:

Plant tomatoes in a rich, loamy soil with lots of organic matter incorporated for moisture retention in a container or bed that does not dry out quickly. Then, mulch. We don’t have an affordable source of mulch up here in Connecticut, so I rarely mulch my vegetable garden.

I also recommend a drip irrigation system. When I watered by hand, too much water was taken up by the plants too quickly. A drip irrigation system (which is really easy to set up — I still have components from my Florida drip system in the garage) will provide slower moisture which should prevent cracking and stressing the plants. I would probably water every morning (just the tomatoes — the rest of my vegetables had no problem with drier conditions — except the pumpkins).

Is there a use for grow bags? I honestly am not sure. They tend to dry out quickly. The felt grow bags (which I did not test) should dry out slower, but soil moisture evaporation is definitely fast in a grow bag. If grow bags are wrapped in something that would help prevent evaporation, that could help.

I really love the portable, impermanent nature of grow bags. It was so easy to build welded wire cages that not only support plants but protected the plants from creatures. The bags themselves were easy to sew, and the cost was minimal. The soil can then be returned to the compost pile, turned in, and replenished. The welded wire is reusable for years.

Thinking about starting seeds . . . it is so easy.

Thinking about starting seeds . . . it is so easy.

Additional stuff I learned about growing tomatoes:

  • Fruit won’t ripen if temperatures are too high – hotter climates should grow tomatoes in early spring and shade or protect summer tomato plants. Spring and fall is best for tomatoes.
  • Fruit will get eaten by slugs (and other creatures) if allowed to sprawl on the ground. Fencing is probably necessary. Keep chickens out.
  • Tomato plants brought home from a nursery or garden center can introduce pests, diseases and viruses. I had this happen and had to rip out a lot of plants year before last, bagging them up and sending them to a landfill (do not compost diseased tomato plants)
  • Starting tomato plants from seed is really easy and only requires a few weeks’ head start. So many more varieties to choose from, too.
  • Tomatoes grow just fine with less than 12 hours of sunlight, though they will need strong support since the plants will be leggier.

Grow bags in back yard garden had less drying out, but they were in the shade for hours every day.

Grow bags in back yard garden had less drying out, but they were in the shade for hours every day.

I still consider myself a tomato novice, but I am learning more every year. And just when I am figuring out how to grow vegetables in New England I am leaving. I will be moving back to Texas very soon.

Happy gardening, everyone!


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