A Planting and Harvest Calendar for the High Desert and Arid West

Jan 18, 2012
Evelyn Gaspar

Mid-April, peppers under plant protectors, celerys - Evelyn Gaspar

A detailed planting calendar from the High Desert provides a continuous harvest and is also useful for much of Zones 6, 7 and 8 and the Arid West.

In the High Desert, some say, "You can't grow anything here." Others do grow dozens of different vegetables and herbs. The secret: It's all in the timing.

The window between the last frost and stressful summer heat can be less than 60 days here. However the corn, melons and tomatoes can be downright memorable and there is a succession greens, legumes and root crops that continues almost year-round.

The trick lies in strategies such as bracketing planting dates, starting seeds indoors, using plant protectors, choosing varieties based on "days to maturity," planting in furrows instead of hills and above all in using a fine-tuned planting calendar based on your own climate norms. Here's a start; a calendar that has worked for one family for over 20 years.

The High Desert Regions of the Southwest include the Mojave and Great Basin Deserts and parts of the Sonoran and Chihuahan. This calendar comes from California's Antelope Valley, in the Mojave, where winter lows often drop into the 'teens and summer highs often climb into the 'teens. At 2,900 feet elevation and 34 degrees latitude, it has frost dates close to the mean for communities across the High Desert.

The last frost dates here are April 3 (50%) and May 2 (90%.) So one year in two there's a frost later than April 3; and one year in ten a frost later than May 2. Locals think of April 15 as the "average" last-frost date; that's when they feel confident about setting out tender plants, realizing protection may still be needed.

The period of possible heat-stress begins on June 21. Cool weather crops will finish their season by this time; while warm-season crops must have root systems well-established in the soil before the onset of high temperatures and hot winds.

This calendar comes from a family that really enjoys fresh vegetables, has eclectic tastes and grows all its own produce. They check "days to maturity," for each variety, making sure it'll produce before the season changes. Some early corn, for example, is ready in 50 days, some late corn, 120. In this climate, they get the best quality and abundance with an early "Super-Sweet" set out in Mid-April. Harvesting in late June makes room for melons that are already started around the area and even between the rows.

In late summer they start some fall crops (winter lettuce,) some to harvest through winter (daikon, kohlrabi,) some to winter over and produce in early spring (fava beans, cabbage) and some that may do any or all of those things depending on the weather (kale, onions, beets.)

The Sample Calendar

January (3 months before average last frost)

Start seeds indoors for tomatoes, peppers, eggplant, celery, parsley, China peas, cabbage, onions, chives, okra and French sorrel.
Start sweet-potato vines indoors.

February (2 months before last frost)

Set out starts for artichokes, asparagus, horseradish, French sorrel and rhubarb.
Start seeds indoors for lettuce, Swiss chard, kohlrabi, broccoli, cauliflower.
Plant out China peas, or sow directly in the ground.
Sow spinach, collards and spring radishes.

March (1 month before average last frost)

Set out celery, parsley, lettuce, Swiss chard, cabbage, broccoli, cauliflower, kohlrabi.
Set out seedlings or sets for chives, onions, shallots, leeks, garlic.
Set out strawberry plants.
Sow beets, carrots, turnips, mustard greens, collards, more radishes.
Start seeds indoors for basil, zucchini, tomatillos, ground-cherries, beans and corn.

Early April (one or two weeks before average last frost)

Sow beans, corn and zuchinni or set out plants with protection.
Sow cilantro and dill.
Set out starts for potatoes and Jerusalem artichokes

Late April (at the time of average last frost and following 2 weeks)

Set out tomatoes, peppers, eggplant, tomatillos, ground-cherries and okra under plant-protectors.
Start seeds of sunflowers, cucumbers, melons, summer squash and spaghetti squash indoors.

May (or after the 90% last-frost date, when the weather has settled and the soil is warm)

Remove plant protectors, but continue to keep an eye on weather predictions.
Plant out or sow seeds for sunflowers, basil, melons, cucumbers, spaghetti squash and pumpkins, Southern peas.

Late May and Early June (when the weather is warm, but at least three weeks before danger of heat-stress)

Set out sweet potato starts.
Set out or sow watermelon, winter squash and gourds.

Mid-June (Before heat-stress sets in)

Harvest all cress, kale, spinach, lettuce, Swiss chard, cilantro, radishes, beets, green and China peas and Oriental cabbage

Late August

Start seeds of kohlrabi, celery, onions and garlic in shade.

September

Plant cabbage, kale, kohlrabi, fava beans, winter radishes, cabbage, beets, winter lettuce in the ground or in pots.

Early October

Set out seedlings of cabbage, kale, kohlrabi, fava beans, winter radishes, cabbage, beets, onions, winter lettuce.

Late October or November (just before the first frost)

Watch weather predictions and harvest all tender crops before frost: basil, beans, southern peas, corn, tomatoes, peppers, eggplant, tomatillos, ground-cherries, melons, cucumbers, sunflower seeds, okra, squash, pumpkins and gourds.
Dig sweet potatoes before the ground freezes.
Bring some sweet potato vines indoors and start cuttings for next year's crop.

December (four months before last frost)

Start seeds or sets of garlic, leeks, onions and shallots indoors.
Start seeds of very early Oriental greens such as fun-jen and tah-tsoi indoors

Constructing and Using Your Own Calendar

To personalize this calendar, determine the average first and last frost and heat-stress dates for your area. Then replace or adjust the dates listed above.

Next choose varieties and strategies that fit your needs.

Strategies

Choose a protected location. Arrange for morning sun, afternoon shade and protection from wind.
Improve the soil. Desert soils lack nutrients, beneficial microorganisms, and a structure to hold a balance of water and oxygen. Adding organic material such as mulch, compost and manure solves all these problems. Don't be stingy; if you can't see a change in the soil's color and feel between your fingers that it's more friable, you haven't added enough. This can be expensive, but is worth it in the long run. And you may find free sources. Dairies, stables, and neighbors who have animals are potential sources. Make sure, especially with horse manure, that it's been aged and hot-composted so you won't bring weed seeds and insect eggs into your garden.
Use an inoculant on bean seeds. Supplying nitrogen-fixing bacteria speeds and increases production.
Choose varieties by their "Days to Maturity. Also check how long harvest will continue. You'll want this information to rotate crops through the seasons.
Bracket planting dates. Weather varies from year; so try a few plants a week before the recomended date and hold a few after your main planting to replace any are damaged.
Start plants in pots Make the most of a short spring window with plants already strong and robust before they must face the weather. This means growing them with adequate light. You may decide you need a cold frame, or even a greenhouse since desert homes are usually built with windows well shaded from the sun. Starting root crops in pots is not usually recommended. The trick is to plant them out a few weeks after they germinate. If you buy started plants, look for larger ones rather than seedlings.
Plant in the furrows, not the hills. Don't plant in hills, ridges or raised beds. That technique drys and warms the soil where Spring is cold and wet. In the desert, opposite strategies are needed. Planting in the furrow insures that seedlings will get the full benefit of any moisture. It also shades and protects them from wind.
Use plant protectors. All kinds of recycled items can be turned into plant protectors. The essentials are: a translucent or transparent material to let in light; an opening near the top to vent excess heat and an anchor against wind.

Growing one's own food is an action to slow global warming. And as the weather becomes more unpredictable everywhere, strategies from the High Desert can be a help.