Summer Vegetables in Davis
(frequently asked questions)
Published in the Davis Enterprise, 20 April 2000
The long, hot summer in the Sacramento Valley makes it easy for us to grow the summer vegetables that love heat. Just look at the agricultural crops grown locally and it gives you an idea what will do well in your garden.
It's no surprise that tomatoes have been a leading crop in this area for years -- just watch for the piles of hard, ripe fruits at every sharp curve in the road on the way to the weigh stations!
Field corn is the other major field crop.
Bell peppers were grown commercially near Dixon at one time, and some of the larger seed companies produce seeds of melons, squash, and cucumbers in Yolo and Solano counties. Sunflowers (grown for oil) have been an increasing and profitable crop for farmers in Solano county. Dried beans are an important cash crop for many farmers. Spice Islands grows heat-loving herbs on a farm west of Dixon.
So what are the summer vegetables that grow well here?
Tomatoes, bell and hot peppers, eggplants, and potatoes are all members of the Nightshade family that thrive here.
Green beans and dried beans are very easy. Sweet corn is easy if you have enough room.
Squash (zucchini and crookneck are among the best known) all produce heavily. Melons (cantaloupes, honeydew, watermelon) and pumpkins can be grown if you have ample room.
Sunflowers are easy, fast, and fun for kids to plant. Okra, traditionally a southern vegetable, thrives in our hot summers.
How about peas, lettuce, broccoli, cauliflower, and cabbage?
No. Those are cool-season vegetables, which do well when planted in the fall or very early spring. They don't tolerate our summer heat. Beets and carrot seed can be planted as late as April for production in the early-to-mid summer.
How much sun do summer vegetables need?
A minimum of 4 hours of direct sun, and full sun is best. Peppers and basil will grow adequately in part shade, and cherry tomatoes will give some production in part shade.
Can I just plant directly in this clay soil we have here?
Most of Davis' subdivisions were built on agricultural land that was producing good farm crops before the houses were built. But our soils are mostly mineral, with very little humus (humus is created by decomposing compost), and the clay content makes the soil hard to work with a shovel or tiller. Soak the soil a few days before you plan to turn it. Then add an inch or two of compost and/or manure to the surface and turn it to the depth of the rototiller or shovel. Plants will grow faster, and seeds will germinate more readily. Adding some more compost each time you plant a summer or winter garden helps to increase the humus.
Is it too early to plant?
Is there anything I can do to plant earlier?
When is it too late to plant?
If the night temperatures are below 50, tomatoes will sulk but will recover and grow as it warms up.
Peppers and eggplant may be stunted all season if they are put in before temperatures are above 55. Gardeners often report slow starts and poor yields on peppers and eggplant after any unusually cool spring.
Every year is different, so going by the calendar is less effective than watching the night temperatures. The fact that they're available in garden centers and chain stores isn't an indication, either -- retailers can only say "it's too early" so many times!
In reality, it's the soil temperature that really matters, so you can plant earlier if you do something to make the soil warmer than it normally would be.
Raised beds heat up faster.
You can cover the plants with a light plastic product called "row cover" or put a Wall-o-Water on each one to create a greenhouse effect.
You can mix lots of compost in (including some manure), mound the area up by several inches, and then mulch the plant with black plastic after you plant it.
You can continue to plant summer vegetables into June, though your yields will be late. Bush beans and corn produce large crops all at once a certain number of weeks after planting, so successive plantings should be done every 3 - 4 weeks. Pumpkins can be planted as late as July 1 to have Jack-o-Lanterns for Halloween.
So, is it ever too HOT for these vegetables?
Not for them to grow, but fruit production may be inhibited temporarily by heat waves. Flowers of tomatoes, peppers, and beans will be damaged above 90 and will drop off without setting fruit, so with our typical cycle of very hot spells followed by periods with cool delta breezes, we get fruit setting every few days. Long hot spells may lead to periods later with little fruit. Some varieties are more sensitive than others. The flowers of the 'Beefsteak' type tomatoes will be damaged above 85, which means it's a rare summer day that they'll set fruit here! They grow just fine, even to 8' or more, but usually don't yield well. By contrast, 'Heat Wave' is a new tomato introduction that will set fruit even above 90.
Extreme heat when corn is flowering can actually kill the pollen and prevent ears from developing. This is rare, but it did happen to gardeners in 1999 if their corn was flowering during the extreme hot spell we had in July.
How should I water my vegetables?
Slowly, deeply, and fairly infrequently. A drip system is ideal, because overhead sprinkling leads to fungus diseases. Water young plants every 3 - 4 days until established. Then most of them prefer watering every 5 - 6 days. Tomatoes should be watered about half as often and twice as long as your other vegetables. More water leads to more plant and less fruit!
What's all this jargon I hear about tomatoes: determinate, indeterminate, VFN,
And is the thing a fruit or a vegetable, anyway?
Most tomatoes are indeterminate: they grow like a vine, all season, and continue to flower and fruit as long as temperatures allow them to. This means they may grow to 8 - 10' or more, and produce LOTS of fruit. Most cherry tomatoes, and familiar varieties such as 'Better Boy' and 'Champion' are indeterminate.
Determinate tomatoes grow to a certain height, flowering as they do, and then pretty much stop flowering. They produce heavy yields, but on more compact plants and their season ends earlier. 'Ace' and 'Roma' are determinate, and great if you're limited for space.Just to confuse things, 'Celebrity' is an outstanding variety that is "semi-determinate" -- it grows steadily but not as big as indeterminate types, and keeps flowering and fruiting. And recently some "dwarf indeterminate" types have been introduced! These have shorter distances between the leaves, so the plants are relatively compact but keep flowering and fruiting until cold weather.
The VFN designations indicate that the plant is resistant to certain pests: Verticillium Wilt, Fusarium Wilt, Root-knot nematodes. The first two are soil fungi and root-knot is a worm-like organism that infests plant roots. These can be common here, especially if your home was recently built on old tomato fields! We recommend moving your garden location for tomatoes, peppers, eggplants, and potatoes from year to year to prevent a build-up of these soil pests.
Heirloom vegetables, as the name implies, are old varieties that have been preserved by gardeners over the years. Many of these have wonderful flavor or unique shape or color, but may not be as productive as modern hybrids. 'Brandywine' tomato is a well-known heirloom that's been around for over a hundred years. Gourmet vegetables are generally European varieties that are extra flavorful. 'Dona' and 'Carmelo' tomatoes are two good examples, or the 'Corno de Toro' pepper.
If you're planting 3 or 4 tomato or pepper plants, put in a couple of varieties that are reliable, good-quality producers ('Celebrity', 'Early Girl', 'Ace' tomatoes), and then try one of the others. You may discover a new family favorite and understand why people went to special efforts to save those older varieties.
You didn't answer my other question! Is it a fruit or a vegetable?
Oh, yeah. Botanically the tomato is a fruit (a berry). Back in the late 19th century most of our tomatoes were imported and fruits were taxed at a higher rate than vegetables. Produce buyers sued on the grounds that the tomato is traditionally used as a vegetable (i.e., in salads) rather than as a fruit (i.e., as a snack or dessert). The Supreme Court upheld this so legally the tomato is a vegetable.
O.k.., you've got all these different kinds of tomatoes and peppers. What's your
That's a whole 'nother article!
See also our other articles:
Everyone loves tomatoes
Peppers and tomatoes
Tomatoes: a primer
© 2008 Don Shor, Redwood Barn Nursery, Inc., 1607 Fifth Street, Davis, Ca 95616
Feel free to copy and distribute this article with attribution to this author.
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