Good Enough To Eat: Big pots are just fine for growing tomatoes

Santa's suit isn't the only red item that stirs interest this time of year. I get more mail on tomatoes in November and December than during the growing season. A recent letter from a Seattle reader is the basis for this column.

Q: Because of lack of space in my garden and limited sun, I planted five tomato plants in pots (10-inch) and set them over the crawl space access (south side). Two Stupice, one Brandywine, one Odoriko and one Sweet 100. The Odoriko died right away. The Brandywine grew but had no fruit. The Stupice had fruit but not in abundance. Same with the Sweet 100.

What varieties do well in pots and what kind of soil preparation is necessary? I use half garden soil and half potting soil.

Cucumbers in potting soil against the south side of the tool shed didn't do well either.

I would appreciate any advice you can give me for next year. J.I., Seattle

C.S.: Though you weren't happy with your tomato production last year, I'd like to commend you for placing your plants where they'd get southern exposure and for thinking about the soil mix in the pots. Those are important considerations when you grow tomatoes in containers. With attention to a few other matters, I think you can have more success next year.

Let's start with the size of your containers. Though it's possible to grow tomatos in 10-inch pots, all but a few dwarf varieties find such quarters too confining for normal root growth and bountiful production. Try 5-gallon or larger pots next year. Be sure any container you use has holes near the bottom for drainage.

The varieties you grew last year are all indeterminate. Typically, indeterminate varieties make large plants that spread horizontally. Moreover, Brandywine often doesn't ripen fruit in our area, and when it does, is a shy producer. Stupice and Sweet 100 were your best choices. If you like their flavors, you may grow them again in larger pots.

Determinate varieties, which form smaller, bushy plants, are better suited to pots. Look for varieties such as Oregon Spring, Siletz, Bush Early Girl, Bush Celebrity and Legend. The drawback of determinate varieties is they produce their fruit over a shorter harvest season rather than producing until frost, as indeterminate varieties do. If you grow determinates, try to have several varieties with different dates to maturity.

Best of all for growing in pots are dwarf varieties such as F Hybrid, Red Robin, Tumbler Hybrid and a compact indeterminate -- Sweet Baby Girl Hybrid. Dwarf tomatoes don't need as much space for their roots and vines and can be productive in containers.

You were on the right track mixing potting soil with garden soil in the pots. I'd suggest cutting the garden soil component to 1/3 of the mix and increasing the potting soil component to 2/3. That adjustment will provide a mix less subject to compaction and more conducive to healthy root growth.

Your letter didn't mention fertilizer. If you provide tomato plants too much nitrogen early in their development, that element stimulates excessive growth of stems and leaves to the detriment of flowering and fruit production. Be very sparing of nitrogen fertilizer before a plant has set fruit. Once it has a good set of fruit, you can be more generous.

Keeping potted plants watered is critical, too. Soil in pots dries faster than soil in a field. It's not unusual for potted plants to need water several times a week during a hot, dry spell. Plants in a field may need water only once a week under the same weather conditions.

Gardeners who grow only five or six plants generally aren't interested in starting plants from seed. So where might you buy tomato varieties best suited for growing in pots? I'd start at your local nursery. Tell the manager what varieties you're interested in and ask whether the nursery will have them in the spring.

If your local nurseries don't plan to stock the varieties you need, call Burpee (800-888-1447) and Territorial Seed Co. (800-626-0866) and ask for their catalogs. Both these companies sell plants for most of the tomato varieties they list.

Chris Smith, who lives in Port Orchard, is a Master Gardener and is retired from the WSU Cooperative Extension. His columns appear in the P-I garden pages on Thursday. Send questions to P.O. Box 4426, South Colby, WA 98384-0426.

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