ASK MARTHA: Early Season Growing - Cole Crops

Learn about Cole Crops with Martha

Question: Hi Martha: I keep hearing the term “cole crops”. What exactly are they and how do I grow them?

Martha: I’m happy you asked this question! Cole crops are among my favorite vegetables I grow on my farm and easy-to-grow, as well. The term cole crop refers to any of the various plants belonging to the Crucifer (Cruciferae or Brassicaceae) family, and include broccoli, cauliflower, cabbage, turnips, kale, kohlrabi, collard greens, broccoli rabe, and brussels sprouts.  

This group of plants grow best, when temperatures are below 80 degrees F. during the day, (25 C.) and are below 60 degrees F. (15 C.) at night. Unlike other plants, cole crops can be planted in the garden before the last spring frost. 

Cole crops prefer cool weather and will often bolt (go to flower) when the weather gets too hot. Because they prefer cooler temperatures, they are often mistakenly referred to as “cold” crops. 

Cole crops grow best in well-drained, moist soils that contain lots of organic matter. (Use Miracle-Gro® Organic Raised Bed & Garden Soil to supplement your soil). Most of these plants are also shallow rooted and do not compete well with weeds, so be vigilant with weed control. 

Cole crops like to be grown in full sun. However, since they need cool temperatures to thrive, your vegetables will be just fine in a partly shaded area. All cole crops can grow just about anywhere in the U.S. but the best time to plant them is what varies. To be sure of your planting time, begin by using USDA hardiness zones to help you decide if they will thrive in your area. To find your zone, consult the USDA hardiness zone map.

Cole crops, with the exception of peas, are easier to grow from transplants rather than direct seeding into the garden. Starting with transplants means your vegetables will be ready to harvest sooner (usually by 2-3 weeks), meaning they’re more likely to be ready before it gets too hot. 

For spring planted crops, most cole crops can be started from seed 6-8 weeks before the last spring date and are ready to be “hardened off” and then transplanted outdoors 2-4 weeks before the last spring frost. (The exact time may vary depending on each vegetable – consult seed packets for specific information.) Hardening off your seedlings gradually helps acclimate them to outdoor elements so that they can be successfully transplanted into your garden.

Here are some spring cole crops from my garden last year. What will you try this year?

Measure the area for cabbage, the seedlings should be spaced at least 12 to 18 inches apart in the row.

Gently remove each seedling out of the tray. Seedlings should be about two to three inches high before transplanting, and after the seedling has its two “true leaves.” True leaves are the leaves that grow after the initial seeds cotyledon leaves appear.

Cabbage seedlings have roundish leaves with very small teeth. As they grow, they get a thick center stem and then the green or purple cabbages in the center.

The seedling should be planted at the same depth it was grown in the tray. Scoop a handful of dirt to make a hole.

The right time for cabbage harvesting will depend on the variety of cabbage planted and when the heads mature. Look for heads that are firm all the way through when squeezed – that’s when they’re ready.

Red, or purple, cabbage is often used raw for salads and coleslaw. It contains 10-times more vitamin-A and twice as much iron as green cabbage.

The cauliflower also looks great. Cauliflower is filled with nutrients. They hold plenty of vitamins, such as C, B, and K. Cauliflower is ready to harvest when the heads are six to eight inches in diameter. When picking, cut the stalk just below the head, leaving a stem of about two inches long.

Kohlrabi, also called German turnip, is a biennial vegetable – a low, stout cultivar of wild cabbage. White kohlrabi bulbs have a neutral, sweet, and subtly peppery flavor close to broccoli, turnips, or cabbage, but bulbs are much milder. The leaves and stems are also edible and have a taste similar to collard greens or kale.

You can find green, purple, white, and even blue fleshed kohlrabi. Typically found at farmers markets, purple kohlrabi is favored for its crunchy texture and sweet flavor, utilized in both raw and cooked dishes.

Article by Martha Stewart, as part of the Growing with Martha Stewart partnership.