Cool Season Crops

"Planting the right cool-season crops"2012-08-24 by Pam Peirce [goldengategarden.typepad.com] for "San Francisco Chronicle" [http://www.sfgate.com/homeandgarden/goldengategardener/article/Planting-the-right-cool-season-crops-3813871.php]:

As summer speeds along, and squash or beans start to get that beat-up, late-season look, Bay Area gardeners begin to wonder what can replace them. In many of our nation's gardens, this late-summer planting would be called "putting in a second crop." Here, the last half of the year offers chances to put in two or even three plantings of one thing or another (and then to start the spring garden as early as February). Happily, much of the prep and planting can occur before winter cold and rain set in, then we can let rainfall take care of all or most of our watering for a while.

Vegetables that will grow well into fall and winter are those known as cool-season crops. These include all of the cole crops (cabbage, cauliflower, broccoli, kale, etc.), root crops (such as carrot, beet, parsnip, turnip, radish), leafy crops (mustard, bok choy, chard, arugula, lettuce, spinach) and cool-season legumes (pea and fava bean).

Some of these crops will grow until December or January, and then will flower in about March. In most cases, this flowering marks the end of the crop's usefulness in the kitchen, so we want to eat it up before then. What's important in planting these crops, which are biennials, is to be sure they have time to get big enough to harvest before their flowering periods. If planted too late in the year, kale or carrots will bloom in spring while we are still waiting for them to produce enough leaves, or big enough roots, to be worth picking or pulling. (See "About biennials")

Annual crops complete a life cycle in under a year, though we generally eat them long before that. Some annual crops reach harvest size so fast that you might get in more than one late-summer or fall planting in succession. Examples are mustard, bok choy, lettuce, radish, spinach, cilantro and arugula. Replant every few weeks. After about September, set out seedlings of lettuce; otherwise all of these can be grown into fall by direct-sowing the seeds.

Inland vs. coast
In the Bay Area, late-summer and fall planting times for most of the cool-season crops are not "one size fits all." They depend on the microclimate of your garden. Microclimate maps and planting calendars, such as maps and four calendars in my book "Golden Gate Gardening" (Sasquatch Books; 2010) offer very helpful guidance. Then you can use experience with your particular garden to fine-tune planting times for the best results.

Near the coast, where late summer into fall is cool and often foggy, you need to get cole and root crops in sooner because the cool days and nights will slow their growth. In microclimates with warmer late-summer and fall days and nights, you should plant these crops later. This is for two reasons. First, these crops won't perform well while summer is still hot. Second, after the worst of the heat has passed, the still-warm inland fall weather will let these crops catch up to the more coastal plantings.

For example, in chilly, foggy locations, a second-half-of-the-year kale crop is best planted in July or August to bear plenty of leaves all fall and winter. In the San Jose region, gardeners plant a late kale crop in August and September, while in the Walnut Creek region, with its very hot summers, this kale planting is more likely to take place in September or October. For broccoli (annual or biennial types), the times are: near the coast, July and August, or possibly early September; in or near San Jose, August through October; and in or near Walnut Creek, October or November.

Planting time differences for peas and fava beans (overwintering annuals) can reverse this pattern. In near-coastal microclimates, peas and fava beans for winter growth are best planted in November, while inland gardeners may plant them as early as September. This is because they will grow slowly through winter months, but the winter months are colder inland, so they need a bit more time for a jump-start.

Garlic, which would be perennial if we didn't harvest it, is planted in October or November across the region, to produce mature heads in late June. Be sure to plant it where you can most easily withhold irrigation once its lower leaves begin to yellow in about May.

Ideally, before the crop comes out, you'll be thinking about what to plant next in the space it occupies. This will give you time to order seed of a special variety or grow some seedlings yourself. With a little practice you can be planting and replanting in a seamless succession and eating from your garden every month of the year.

Growing tips
How to make the most of the year's second half:

Add fresh organic soil amendment and fertilizer to sections of your garden you are about to replant. If your vegetable plants have been small, be bolder in your amendment and fertilizing efforts.

Grow fall and winter crops in the sunniest locations possible, though some, including lettuce, arugula and spinach, will continue to produce in bright or open shade.

Grow most cole crops from seedlings, which you can buy or grow five to seven weeks before planting out. In cool summer areas, you can start these seedlings outdoors.

Generally speaking, loose-leaf and romaine lettuce varieties handle cold better than crisphead or butterhead types. Some varieties are listed as "cold resistant."

Use large spinach varieties such as 'Oriental Giant' or 'Viroflay Giant.' For spinach, use plenty of nitrogen fertilizer, such as aged chicken manure or worm compost.

Have a sturdy trellis in place before you sow peas: 4 to 5 feet tall for bush peas, 6 feet or taller for pole peas. Use row cover to protect the seed rows from birds, snails and slugs until the plants are well up.

For a longer-lasting harvest, start early and late varieties of cole crops such as broccoli or cauliflower at the same time.

To avoid leaf blotches from leaf miner insect damage, set out Swiss chard seedlings in early September, and cover with row-cover fabric until the leaf miner enters winter dormancy (in around mid-October near the coast, maybe a bit later inland).

What about frost?
Most cool-season vegetable gardens survive mild and/or brief frosts, and some live through an occasional hard freeze even without special protection. Kale, collards, parsnip, turnip, Swiss chard, spinach and long-season broccoli, cauliflower or cabbage can survive short periods as low as 0 degrees Fahrenheit. Early broccoli, cauliflower or cabbage, carrots, beets, lettuce and radish tolerate as low as 10 degrees. Peas are moderately cold hardy, but are damaged by heavy frosts. On nights when frost is predicted, you can use cardboard boxes, sheets (propped away from plants on buckets or stakes) or row cover to protect plants.

Seed sources
* Bountiful Gardens (bountifulgardens.org, (707) 459-6410)
* Johnny's Selected Seeds (johnnyseeds.com, (877) 564-6697)
* Kitazawa Seed Co. (kitazawaseed.com, (510) 595-1188)
* Nichols Garden Nursery (nicolsgardennursery.com, (800) 422-3985)
* Territorial Seed Co. (territorialseed.com, (800) 626-0866)

About biennials
A biennial plant typically lives longer than one but less than two years. These crops do not flower until after they're exposed to a certain amount of winter cold. After flowering, they ripen seed, a process that requires several months, and then the biennial plant dies. Biennial vegetable crops include kale, collards, Brussels sprouts, cabbage, some kinds of broccoli and cauliflower, carrots, beets, turnips, parsnips and Swiss chard.

Note: Early broccoli and cauliflower varieties have been bred to be annuals, so they will produce edible flower buds before winter's cold. Late types (over 120 days to maturity) produce their edible flower buds in spring.