Extending Tomato Season

A long-standing goal in my family is to serve fresh tomatoes on Christmas Day. We don’t always succeed in extending our harvest to the end of the year, but it’s a treat when we do.

Most of my tomatoes for this year have been in the garden since April, and I have a few tricks for encouraging them to last. I also save space to plant cool-season tomatoes (yes, there really is such a thing) in August or early September.

Type Matters

Tomatoes—and beans and peas—come two ways: as bushes and as vines.

Bush, or determinate, types typically stand on their own. Their fruits ripen within a relatively short window and harvesting a wave all at once is useful for preserving or canning.

Vining, or indeterminate, tomatoes don’t produce as many fruit at a given time. But the vines continue to grow, flower and ripen fruit for months. Only eventually do they succumb to frost, rain, cold soil or exhaustion.

I grow both types. For traditional springtime planting, I choose indeterminates that promise to produce all summer. For late summer and fall, I plant determinates because their time to develop is limited.

Cool-Season Varieties

It’s late for growing tomatoes from seed for an August planting, so look for transplants at local nurseries. I avoid plants already bearing fruit. They’re not likely to last beyond summer.

Instead, seek seedlings developed for cool, short growing seasons in Alaska, Czechoslovakia and Siberia. Their names often reveal their origins, such as Manitoba, Northern Delight, Oregon Spring, Scotia, Siberia, Stupice and Zaryanka Sunrise. I’ve had good luck with Bush Early Girl, too.

Location

All tomatoes, including cool-season varieties, insist on at least six to eight hours of direct sun daily. Depending on the arc of the sun in your garden, your summer and late-season tomatoes might go in different places.

Excellent drainage is critical. Tomatoes are at their best if the top inch of soil goes dry between waterings. Plants with constantly wet feet can produce watery, bland fruit and be more susceptible to disease and early death.

It’s easy to control irrigation during our dry summers. I’ve found that being stingy with water extends the lives of my spring-planted tomatoes as well.

But rains can cause the cool-season bushes to collapse.

A good strategy is to plant in large containers filled with a fertile, fast-draining mix of potting soil and topsoil. Fifteen-gallon black plastic nursery pots are an option. They’re not attractive, but they’re functional. Their dark sides warm the roots during the day, while the soil drains faster than in the ground. Both attributes speed up growth and ripening. And if heavy rain is forecast, you can haul them under an eave or cover them temporarily.

Planting Time

In August or early September amend the bed with rich, fresh-smelling compost. In containers, any high-quality potting soil should be fertile enough. Then dig extraordinarily deep holes. Unlike other vegetables, tomatoes sprout new roots where their branches meet their stems.

This is key to extending your plants’ lives. Match the level of the nursery pot and your tomato will produce a standard network of roots. But bury the first few sets of branches and you’ll potentially double or triple the root mass, making for a sturdier, more productive plant with greater longevity.

Because you’re leveraging those expanded roots, space your plants at least two feet apart or plant only one per container to avoid competition for nutrients.

Irrigate your plants with drip hose or soaker hose, or by shaping substantial basins around each, then filling the basins with water from a bucket or a hose equipped with a shut-off valve. If the adjacent soil is dry, it may wick away what you’ve applied. That first, good soak may take several applications over several hours.

Once the soil is saturated, apply an inch-thick layer of loose, well-aged compost, topper or decomposing straw to help insulate the soil from temperature swings, retain moisture and inhibit weeds. Water again to wet the mulch.

At the outset, and depending on the weather, you may need to water daily. But as the plants grow and their upper leaves begin to shade their roots, start tapering off with a goal of watering every seven to 10 days by the time your plants begin producing fruit. The idea is to apply as little water as possible to intensify the flavor, but not so meager that the plants go into a tailspin and perish.

Care and Feeding

Harvest consistently. After their initial push, your indeterminate plants may start looking punky. But if you let them go, the remaining fruit will over-ripen and set seed, prompting the plants to go into their inevitable decline. You must keep harvesting those leggy branches to promote further flowers and fruit.

On the flip side—if temperatures drop and your determinate tomatoes stay green, clip whole branches and hang them in a dry room, out of direct sunlight, to encourage the fruits to ripen. I’ve had mixed results, but it’s worth a try.

Some folks apply a mild solution of fish emulsion every six weeks to boost their summer tomatoes. I’m not that disciplined. However, I re-work the soil with every new crop, rotate my tomatoes every year and mulch with compost to maintain fertility during the growing season.

Nonetheless, mild doses of fertilizer may keep your plants nourished, thereby helping them to keep growing. Products containing humic acid work well. Avoid fertilizers high in nitrogen, which promotes bushy, beautiful foliage at the expense of fruit. Slow-release, granular fertilizers may just sit during colder weather, so apply any nutrients then in liquid form.

Also know that your cool-season plants may not look pretty, with their leaves and branches torn and tattered by December. But that matters little if you’re still able to pluck ripe, tasty tomatoes from your garden as late as the holidays.