Sonoma County Master Gardeners Helping Sonoma Gardeners

Tomato Tales

Like almost everyone who gardens at all, tomatoes always top the list for my vegetable garden each year. Nothing seems to pay off in both quantity and quality compared to what can be store-bought like tomatoes. Sure, zucchini is super easy, and provides unbelievable quantities, and fresh-picked corn is like nothing from the supermarket, but there is just something about your own, vine-ripened tomatoes. Further, preserving the excess crop for gray winter-day use is a snap—just quarter them, stick them in ziplock bags and throw them in the freezer - no having to leave stealth early-morning brown paper bags of squash, unwanted, on neighbor’s porch steps.

For years now, heirloom tomatoes and classy cultivars of every size, shape, color, stripe have been readily available as plants—no need to start anything from seed, unless you like that drill. I’ve had my share of success and failures—more successes, fortunately, and the years of bounty for ruby, red-black, golden, green, red/gold striped tomatoes have been great.

Of course three years ago, we lost most everything to verticillium wilt. Several early years saw some loss to blossom-end rot, before we learned to add calcium at planting, and make sure that watering wasn’t uneven. Horn worms claimed a share one year when they hit while we were on an extended vacation, and unaware of their presence, and whitefly are around most years, requiring a certain amount of diligent treatment.

I was tempted, for years, to plant early, being the impatient type, and had to learn from experience that in my location, on Sonoma Mountain in Glen Ellen, the best results were obtained waiting for the second or third week in May--tomato plants do not grow well until the soil is warm, and planting earlier exposes the plants to pathogens. The minimum soil temperature for tomato growth is 55ºF to 60ºF. The optimum growing temperature for tomatoes is above 70ºF. Temperatures below 57ºF will actually delay growth and encourage disease. In addition, night air temperatures should be above 45ºF. The official last-frost date in Sonoma County is April 15th, but we had freezing temperatures in some parts of the county this year in late April--another reason that waiting until mid-May is a safer bet. The plants must have six to eight hours of sunlight a day -- including full sun from 10AM to 2PM, which is the best, most direct light of the day.

Many sources recommend moving tomatoes around in the garden each year, so that they have the benefit of different soil, and a different location, and to minimize disease and pest recurrence—but like many gardeners, my garden plot, and choices are limited. Since I garden in raised beds, I leave them in the same location, but remove and replace the soil with new soil and compost annually instead. If that doesn’t work for you, then follow these guidelines: tomatoes need loose, rich soil. Loosen the soil, and turn in plenty of compost, about three feet in diameter, two feet deep for each plant. Test for acidity—tomatoes absorb nutrients best when the ph is around 6.5 to 7.0—neutral to slightly acidic soil.

Tomatoes are heavy feeders with a deep root system, and my 2½-foot deep bed of new planting medium accommodates them. I add a little bone-meal, a handful of agricultural lime (for that calcium) and a bit of organic fertilizer (exactly what changes year to year—maybe compost, maybe turkey manure) into the bottom of the planting hole. Seedlings gain a boost if planted deeply (extra roots will develop from the buried stem)--to the depth of the first or second set of true leaves. I’m a believer in the trench-and-lay-down method. I remove the lowest leaves, dig a short trench, rather than a hole and plant the actual plant on the side, and bend the stem so it curves, and the upper part of the plant leaves dirt-level vertically.

I used wire tomato cages, or “teepees” for years until a saw a fellow master-gardener’s tomato patch two years ago, with a “fence” of graduated mesh-wire down the row. With this method, it takes a bit of work to weave the stems into the fence as the plants grow, but the result is a vertical wall of tomato plants and fruits that are very easy to pick from both sides. The fruits generally get more sun exposure with this approach, as well.

Plants should be watered deeply and often early in the growing season. Soaker hoses and drip systems are great for tomatoes, as they avoid water on the foliage, which can be problematic. I use drip with in-line emitters—two lines, one on either side of the row of plants, with 1 gph emitters spaced at 1 foot. This seems to give an even and consistent result. Less water, but consistent moisture is needed when the fruit starts to ripen (remember: inconsistent water is one of the causes of blossom-end rot). Plants that have been over-watered have less flavorful fruit and are more susceptible to fungal diseases. Cover the soil with a thick layer of mulch once the soil is thoroughly warmed. (Red plastic mulch was the rage a couple of years ago, and some swear that it results in much higher yields, but I’ve never tried it).

Tomatoes come in dozens of varieties, sizes and colors. The bush varieties are called determinate—which means they grow to a specific size, then flower and set fruit pretty much all at once. Vining, or indeterminate varieties, keep growing, and set flower and fruit all season long (they must be staked, or caged). You can cut them off once they reach the top of your supports, so that they focus their attention on the existing fruit rather than expending energy setting more.

Many have been bred to be problem-resistant, and will have letters behind the named variety: “F” means resistance to Fusarium wilt; “V” to Verticillium wilt; “N” to Nematodes; and “T” resistance to Tobacco Virus. Since it makes no sense to me to have a crop all at once, I plant mostly determinate tomatoes. An alternative strategy might be to mix in determinate plants, of different ripening periods, and/or plant them at different times. Either way, for me the objective is a flow of tomatoes all season long, and as late as possible in the year.

Okay, what varieties to plant? Much a personal preference question. As sweet and tasty as many home-grown small cherry or grape tomatoes are, I don’t have much use for them (too much more work to pick, for one). I love the dark red, almost black types, so Cherokee purple—maroon with dark green shoulders (supposedly developed by the Cherokee Nation, and I’m 1/16th Cherokee), Black Krim, Black Prince, and their ilk are a must (these types all seem best harvested a bit early). I also favor yellow and gold varieties, both for their color contrast on the plate, and for the sweet/acid balance many give—Yellow Taxi, and Golden Jubilee have done well for us. Something green is a must, too. I’ve never had luck with that standby Green Zebra—small fruit, and not too much of it. Aunt Ruby’s German Green is a large, spicy pale green fruit with often a hint of yellow striping. I also think the knobby-topped, misshapen (sometimes called Florentine-type) sorts are a nice addition to the mix: one unceremoniously called Ugly fills this bill, as does Big Beef, and Brandywine Yellow provides both this shape and yellow color. Pineapple produces huge yellow beefsteak-types with beautiful red/pink stripes.

If you live in cooler summer areas of the county, such as west county and coastal areas, you may wish to stick with early maturing varieties, like Early Girl, Dona, and Stupice, or cooler zone varieties such as Bingo, Carmelo, Oregon Spring and Valerie.

But whatever your preference, the time is nigh—better nurseries have a good selection of tomatoes, and there are at least two vendors at the Wednesday and Saturday Farmer’s Markets at the Veteran’s Hall in Santa Rosa with a huge variety of plants just about now.

Sonoma County Master Gardeners’ “Growing Tomatoes” guide

Click here for complete UC information on tomato pest control

An extensive white paper on tomatoes, including a comprehensive table of tomato problems from the UC Davis Vegetable Research Center.