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New Mexico State University

New Mexico State University

News Center

Plant Crops Now for Fall Harvest

LAS CRUCES -- Hot, dry winds turned cauliflower curds purple and broccoli bitter in New Mexico gardens this spring. But gardeners can still reap sweet success by planting crops for harvest in the fall.

"Crops like broccoli, cauliflower, cabbage, kohlrabi and green beans are best planted during the summer for fall harvest," said George Dickerson, horticulture specialist with New Mexico State University's Cooperative Extension Service. "Crops that mature in the fall when it's cooler have a higher sugar level and improved taste."

For most warmer areas of the state, fall-harvest crops should be planted in July. Since each crop and variety varies in the number of days to maturity, keep records of actual planting and maturity dates for future reference.

Since spring crops have probably removed a lot of nutrients from the soil, applying compost can help establish young seedlings. Spread a 1- to 2-inch layer of compost over the area and turn it under with a garden fork or tiller. Finally, rake the seed bed smooth.

"Getting a good stand of plants can be difficult in July due to hot weather," Dickerson said. For cole crops like broccoli, cauliflower, cabbage and kohlrabi, he recommends planting several seeds together approximately one-half inch deep. Plant green bean seeds 1 to 2 inches apart and 1 inch deep, with 18 inches between rows.

"The green bean is a legume, which means it produces its own nitrogen," Dickerson said. "Nodules on the roots contain a Rhizobium bacteria that converts elemental nitrogen from the air into a form the plant can use."

If you've never grown green beans in your garden before, treat the seeds before planting with Rhizobium bacteria, available from most nurseries or garden seed catalogs, he advised.

To keep cole crop seeds cool and prevent the soil from crusting, cover the seeds with vermiculite. Keep the soil moist until seedlings emerge.

Flea beetles can be a major problem for young broccoli, cabbage, cauliflower and kohlrabi seedlings. To help deter the beetles, cover each row or hill of seed with transparent, woven polyester row cover. The cover also slows water evaporation from the soil. Support the row cover with small, wire hoops and anchor it on both sides with soil. Remove the cover after seedlings form their first true leaves.

Thin cole crop seedlings to one plant per grouping. Thin green beans approximately four inches apart. Apply nitrogen fertilizer lightly to broccoli, cauliflower, cabbage and kohlrabi every two to three weeks. Water immediately after fertilizing.

"Pull the leaves of the cauliflower plants over their young developing heads in the fall to help blanch them so they have nice white curds at harvest," Dickerson said.

Green beans should be harvested when the pods are filled out but not swollen. Older pods or pods that have failed to fill out should be removed so the plant will continue to produce new pods. Broccoli buds should be harvested before they start to spread apart and flower. Cabbage heads should be firm at harvest, and kohlrabi stems should be well-rounded and hard.