Quick-growing collard greens can be grown as an annual vegetable in all the U.S. Department of Agriculture (USDA) plant hardiness zones. Also known as non-heading or tree cabbage, they grow best in warm weather but tolerate cold weather more than any other members of the cabbage family, including kale.
Collard greens take between 60-85 days from germination to harvest. If you plant seedlings, they will be ready to harvest in 28-42 days. Unlike cabbages, you can harvest collard greens while they are growing, plucking leaves off the stem when you want them. But many people maintain the leaves are sweeter after the first frost.
What Are Collard Greens?
Collard greens are a cole crop, which, like all plants that belong to the mustard or Brassica family, are descended from the wild cabbage. The term cole crops originate from the Latin word caulis that means the stalk or stem of a plant.
So, today when we talk about cole crops, we mean the stem brassicas that include:
- Brussels sprouts
- Collard greens
Even though they are biennials, we usually grow cole crops as annuals.
How do you know when your collard greens are ready to harvest?
Like kale, you can harvest dark green collards at any time during the growing season, depending on when you planted them. They will produce an early spring crop, if you want a summer harvest and/or in midsummer for an early winter or fall harvest, about 60 to 80 days after planting the seed.
Sometimes people grow collard plants for microgreens, but it’s best to use a special sprouter tray if you choose this route. After 5-14 days, when the leaves are open and the young plants are between 1 and 3 inches (25-76 mm) tall, harvest using a sharp knife or scissors.
More commonly, collard greens are ready to harvest when they are 6 to 10 inches (15-25 cm) tall. If you prefer larger leaves, you need to leave wider spaces between the collard plants and wait until they are between 10 and 12 inches (25-30 cm) tall.
If you have planted Georgia Southern collards, you can still harvest when they reach a height of 10-12 inches. In fact, the leaves taste best when they are young.
Just be aware that they mature in about 75 days. And they will continue growing as they grow as tall as 2 to 3 feet (600-900 cm).
When you harvest the leaves of your collard plants, they should be smooth and firm. They thrive in cool weather, and both cool weather and light frost will improve the flavor of a late fall crop.
How does frost improve the flavor of collard greens?
Cool-weather and light frost change the starch stored in collard leaves into sugars. According to the specialists at Colorado State University, cool temperatures will also change the structure of some proteins, which improves the flavor of this cole crop.
What happens if you don’t harvest collard greens?
There are several things that will, or might, happen if you don’t harvest collard greens.
Collard plants will go to seed
Because collard greens are biennial, during the first season the plant will grow and mature. It will bolt, sending up flower stems, and produce seeds in the spring of the second year.
So, if you don’t harvest collards in the first year, it will go to seed. Once the plants have flowered, you will notice that it starts to produce seed pods that look a bit like green beans.
If you want to harvest the seeds, stop watering the plants and let the pods dry out and turn brown. Collect the pods and place them between two sheets of paper towel.
Apply pressure so that the pods break. The seeds should be black when you remove them from the pods.
Collard seeds should be viable for at least 3-4 years. You can store them in a paper bag in a cool, dry cupboard until you are ready to plant them.
Collard plants might be affected by pests and disease
Like all members of the cabbage family, various pests and diseases can affect collards. While the collards grow, keep an eye out for the usual destructive culprits including aphids, cabbage root maggots, slugs, cabbage worms, and cabbage loopers.
In larger gardens, you can use row covers for pest control. But they are not normally necessary for the average veggie garden, even for the most ardent homesteaders.
If you don’t harvest your collard plants simply because of neglect, pests are more likely to attack your collard crop. Or, rather, you are less likely to notice them.
More importantly, if you don’t harvest your collard plants and they self-seed and continue growing in the same spot, diseases can build up in the soil. That’s why horticulturalists warn that they shouldn’t be planted in the same part of your veggie garden every year.
How to harvest collard greens?
Collards grow on a central stem and new leaves come from the center of the plant, at the top of the plant. This means that the older leaves are always on the outside edges.
You can harvest collards by cutting the entire plant at or just above ground level. Or, you can harvest the large dark green leaves progressively, starting at the base of the stem. This way, you will get maximum yields.
When harvesting progressively, the conventional way to harvest the leaves is to remove the oldest leaves first. But you don’t have to do it this way.
You can also harvest the inner, circular rosette at the top of the young plant if you want really tender leaves. If you do this, Prof. Craig R. Andersen of the University of Arkansas Division of Agriculture’s Research & Extension department, recommends tying the top outer leaves loosely together to protect the head from full sun.
Should you wash collard greens after harvesting?
Collard greens are notoriously gritty and must be washed after harvesting.
How to wash collard greens
There are various ways to wash collard greens. Use the method that works best for you, or combine them all.
Many people just swish them in a bowl of water. You will have to refill the bowl of water at least 3 times and carry on washing the leaves until you get rid of all the grit and dirt.
It’s helpful to let them soak in the water for a short while to loosen the dirt. Adding a bit of salt to the water also seems to help.
Can you eat collard greens immediately after harvesting?
It’s best to harvest collard leaves when you need them. Once you have washed them thoroughly, you can cook and eat them.
If you harvest more leaves than you need, you can store them in damp paper towels for 3-4 days. But don’t leave them longer than this because the longer you store them the more bitter they are likely to get.
If you aren’t going to be able to eat the full harvest soon, it’s better to freeze the collards. Blanch the leaves for 3-4 minutes and drain.
Then plunge into an ice-water bath and leave for about 5 minutes before draining again. Pack into zip-lock bags or freezer containers.
How to eat collard greens
You can lightly steam, braise, sauté, or boil collards. If you harvest young tender leaves, you can even eat them raw, though it’s usually best to chop them up finely.
If the leaves are older, it’s best to remove the tough stems and central vein.
Minimal cooking will preserve the dark green color of collards and maintain their vitamin content, mostly A and C. If the leaves are tough, boiling may be needed to soften them. They can take up to 20 minutes to soften.
If you do boil your collard greens, don’t throw out the cooking liquid. Save it to add to soups and stews. You can freeze this liquid too.
Even if a recipe doesn’t call for collard greens, you can use them. For instance, if you are making a stir fry, you can shred or chop the leaves and add them to a stir fry.
In fact, you can supplement your collards in any recipe that calls for ingredients like spinach, chard, or kale.
Collard greens are versatile in more ways than one. They grow in just about every climate type, they can be harvested pretty well throughout the year, and they can be incorporated into a multitude of recipes.
They are also one of the easiest cole crops to grow.
Unlike cauliflower and broccoli, they don’t grow as flower bud heads (which sometimes fail to form). They don’t have tight heads like cabbage or miniature buds like brussels sprouts. These tight formations unfortunately fail quite often.
Not only are there various stages of growth when collards can be harvested, but there are also different ways they can be harvested. Our 2023 harvesting tips will give you all the guidance you need.
If you’ve never considered growing collard greens, now is a good time to think again!