People have been growing collard greens for centuries on every continent. They are known as a staple in the US south. Tour any kitchen garden in the south, and you’ll find collard greens growing there. They are delectable, just as much as their vegetable counterpart kale, which has gained popularity in the US in recent years.
It’s a wonder they’re so popular because they tend to attract a lot of pests. But the secret to growing these large green leaves is to grow them at the right time. Although collards will flourish in summer, they’re less likely to attract pests in winter. And as the weather cools, the flavor of collards sweetens. They’re excellent for any of your favorite winter soups or stews.
Maybe they make up for their attractiveness to pests by being so easy to grow from seed. As long as you have healthy, rich soil, and good fertilizer, growing collards is not difficult at all. As a great companion to many other food crops, they can accompany your favorite garden foods. Old plants can also serve as a trap crop on the tail-end of their life cycle just before they go to seed.
Thinking of growing collard greens yourself? Well, let’s take a look at the essentials for growing collard greens and discuss how you can cultivate your very own crop of collards that will last multiple seasons.
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- NaturesGoodGuys Live Beneficial Nematodes
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Quick Care Guide
| Common Name(s) | Collard greens, collards, couve, kovi, haak, sukuma wiki |
| Scientific Name | Brassica oleracea var. viridis |
| Days to Harvest | 4 weeks to harvest |
| Light | Partial shade to full sun |
| Water | 1 to 1.5 inches weekly |
| Soil | Fertile, loose, well-drained soil, neutral pH of 6.5-7.0 |
| Fertilizer | Full-spectrum foliar applied weekly; slow-release upon planting; high nitrogen |
| Pests | cabbage looper, aphids, cutworms, flea beetle, thrips, root-knot nematode |
| Diseases | Alternaria/cercospora/white leaf spots, clubroot, damping-off |
All About Collard Greens
Collard greens, or Brassica oleracea var. viridis originate in Greece where they’ve been grown for over 2000 years. They are a member of the cabbage family but don’t produce a head as cabbages do. They are also popular in Spain, Portugal, and India. And it’s no wonder they’re a staple in Africa, with its proximity to Greece.
Many famous dishes from the south originate from African meals brought over by enslaved people taken from their homes due to the Atlantic slave trade. We have much gratitude to give to Africans and African Americans who kept collard plants thriving in the south. Because of them, we have healthy, vitamin and mineral-rich greens in multiple varieties.
Collards grow much like their leafy green counterparts. Light green to dark green leaves grow in rosette formation around a central stalk. Stalk color ranges from light green to dark purple depending on the variety. Leaf size ranges from 6 inches to over one foot in size. Larger varieties are prized for their versatility in cooking, and are eaten in a mix of other leafy greens, or lightly steamed and served as a wrap. Some varieties grow up to 36 inches tall. All parts of the plant are edible, though the stalks, roots, and ribs can be tough if they aren’t cooked enough.
Collard green seeds are tiny, dark, and round. They sprout into a double heart-shaped cotyledon, and small immature collard leaves emerge between those. Leaves grow around the central stalk, and if left alone long enough the plant grows small broccoli-like heads that flower into characteristic brassica four-petaled yellow flowers. After flowers bloom and die, seedpods remain and burst open to re-seed the area where the collards grow.
My favorite collard variety is called Old Timey Blue, or Alabama Blue. It’s a southern collard that has been grown on the Blackwell farm in Alabama for at least one hundred years. The leaves are green and the stalks are purple. The leaves get up to two feet in length at maturity making them great for collard green wraps. Search the internet for varieties to see what works best for your situation.
Planting Collard Greens
You can plant collard greens by seed or seedling either in early spring, or late summer. Grow collard greens when it’s temperate so they’ll last through the heat of summer or the cold of winter. Cool weather makes collards happy, and their flavor improves with a nice winter frost.
If you’re planting collards in the ground of your garden make sure the soil is full of rich organic material, fertile, and well-draining. Always plant this southern crop at least 18 inches apart, and search for a sunny spot. If you’re used to growing kale and cabbage, use that experience as your base for collard greens growing. Collard greens grow well in grow bags (we recommend Root Pouch), containers, raised beds — you name it. They are a hardy member of the cabbage family that will thrive in almost any area with the right care. You can grow them easily from seed or via transplant.
To plant collard green seeds, create rows in your garden bed about 30 inches apart. This width prevents wilts and mildews that can ruin your plant. Plant collard greens ¼ to ⅛ inch deep in loose soil in early spring after the danger of the last frost has passed, or in late summer 6 weeks before the first frost. Plant one to two seeds per 6 to 8 inches. Once they’ve grown true leaves, thin the seedlings to about 18 inches apart. You can easily divide seedlings and plant them elsewhere. The same goes in a grow bag or container. Seeds can also be planted indoors.
To transplant collard starts, wait until spring or late summer to put them in the ground in loose soil or a container. Simply remove the whole plant from the pot, loosen the roots that have formed and plant starts 18 to 24 inches apart in a raised row in your garden, container, or grow bag. Soil pH should be neutral, at about 6.5-7.0. You can also grow collards indoors in a sunny window, but you’ll have an easier time outdoors in direct sunlight.
Care
Although collards are pretty easy-going plants, they need a lot of attention, especially in late spring when bugs and pests come out of their winter slumber. Search your garden daily in warmer seasons for areas that need extra love. Take note of these essentials and you’ll have lovely collard greens growing through summer, fall, and winter.
Sun and Temperature
You’ll find collard greens growing in USDA hardiness zones 6 through 10. They are biennial plants in zones 7-10 and reseed to come back each season. I’ve chopped the stalk down in summer leaving just the root to find it sprouting again in fall.
Collard greens prefer full sun to partial shade with at least 5 solid hours of direct sun per day.
It’s best to grow collards in a cool season, in early spring or late summer when it’s 55-75 degrees Fahrenheit. Although they are hardy, collard greens are sensitive to freezing weather and intense heat and must be well-established to weather these extreme conditions.
Young collard plants will burn up in high heat, and stunt easily in frosty weather. Mature plants can handle temperatures as low as 20 degrees and as high as 95 degrees. If your spring is especially warm, use a shade cloth to shelter collard starts from sun rays. Or if your fall is remarkably cold, try a frost cloth.
Water and Humidity
Collards need a lot of water to thrive. Mine are doing great in this unusually wet cool season we’ve had here in Texas. Because it rained almost every day in May, I didn’t have to water my collard greens at all during that month. However, when the summer heat reaches triple digits, I’ll have to remain vigilant and water at least twice a day to prevent browning and burning of the dark green leaves.
Generally, collard greens prefer at least one to one and a half inches of water per week. It’s best to water greens at the base of the plant to prevent powdery mildew or damping-off on tender leaves. If you’re watering by hand, in cool seasons water well once in the morning. In the heat of summer, rise before the sun does to water well and then water again as the sun sets.
The best type of irrigation for growing collard greens is drip irrigation. This focuses water at the base of the plant near the roots, preventing any damage to the leaves above. Irrigation in the form of sprinklers or misters isn’t great for collards as the leaves are prone to disease when they remain wet too long.
Soil
Collard greens like well-draining soil rich with organic matter. Soil pH should remain neutral, at about 6.5-7.0. Since collard greens are leaf-producing plants, they’ll need nitrogen to thrive. Poor soils are not suited to host these greens. Planting collard seeds or starts in prepared soil with good drainage is best. Good drainage keeps the fungal and bacterial diseases the leaves are prone to at bay.
Fertilizing
Where you plant collards determines how much fertilizing they need. I fertilize my leaves with a full spectrum basic foliar feed weekly. This keeps them healthy and lively. I’ll also do a monthly soil soak with the same fertilizer, which contains compost tea, sea kelp, molasses, and apple cider vinegar. If it’s been raining a lot, I wait to apply foliar fertilizer to prevent leaf spots and mildews.
Since nitrogen is essential for leaf production, high nitrogen fertilizer or a fertilizer with low phosphorus works well. Slow release, foliar application, and soil soaks are great for collards. Apply a high nitrogen fertilizer to the base of your plants when they are young. If you want to remove a plant, but leave the root, spread compost over the garden where the plant was to replenish nutrients to the soil.
Pruning/Training
One of the only times it’s necessary to prune is when your plant bolts prematurely. Remove bolts before they flower to keep nutrients flowing into leaf production rather than flower production. Simply snip the bolt about one inch above the first growth point of the leaves with a clean pair of pruning snips.
Search the plant and remove any damaged leaves that could have wilt, mildew, or leaf spot as they appear throughout the life cycle of the plant. Some suggest collards should be staked, but that depends on the variety. If your plants get tall, add a stake to the side to support your fall crop.
Propagation
If you’re growing tree collards, you can take a cutting to propagate them. Most varieties, however, only propagate by seed. This year, I decided to let my collard green plant grow beyond harvest time, and let it flower. Once the flowers died, seed pods grew and fattened. I snipped off the pods and placed them in a paper bag. They popped in the bag, and I separated seeds from the pod detritus. This is the best way to save collard seeds. After you harvest collards and gather seeds you can plant collard greens seeds for another harvest.
Harvesting and Storing
Collards are hardy in the garden, and they’re hardy in storage too. Here are a few ways to harvest collards and store them to share with family and friends.
Harvesting
Once leaves reach a 6-8 inch size, they are ready for harvest. Much like other plants in the cabbage family, simply snap leaves from stems starting at the base of the plant. Alternatively, you can use a hand tool to snip off leaves. You can do this as needed throughout the plant’s entire life cycle in basically any season. You can also harvest the entire plant too. To harvest the entire plant, simply snip it at the base of the soil and cover the root with compost.
Storing
Collards can be canned, blanched and frozen, or stored fresh in the refrigerator.
Canned collards will last at least a year with the proper seal. Please note that these must be pressure canned as they are low-acid foods, and water bath canning is not safe for most leafy greens. Those that have been opened should be consumed within 5 days.
Blanched and frozen collards (which are great for your favorite morning fruit smoothie) will also last up to one year in the freezer. Fresh greens last one to two weeks if they are kept between damp paper towels.
I find it best to only take what I need from the plant and use it right away. If you have many collard plants, canning or freezing could be an excellent solution to storing them before the plant life cycle concludes.
Troubleshooting
Grow collard greens and provide them with the right amount of care and attention and you’ll find dealing with pest and disease problems are no problem. Several issues can arise from improper growing conditions, though.
Growing Problems
Since collards will bolt if it’s too warm, and they’ll experience stunted growth if they’re in conditions that are too cold use frost cloth or shade cloth as needed.
Collards that don’t have enough light will grow long, spindly leaves that won’t taste as good as those grown in the right conditions.
Without enough nitrogen, collard green leaves won’t grow as quickly and could experience yellowing. If this continues for too long, leaf collapse can occur.
Pests
These supple greens are a preferred destination for pests in the spring and summer months. This is why it may be better in some places to grow collard greens in the fall for food, and then allow them to become a trap crop in spring. Search your plant regularly for signs of pests and you’ll be able to keep collards healthy and happy throughout the year.
Aphids and thrips are two insect pests that love to munch on the leaves of your plants. Aphids group up in colonies and feed on your plants for sustenance. They congregate on the underside of leaves and eat small holes through them. Thrips aren’t round like aphids; rather, they are just as small but long and thin. They tend to change the structure of leaves as they feed, contorting them as they go. Control both with a strong stream of water in less serious cases. In more intense cases, use neem oil or insecticidal soap to prevent proliferation.
Caterpillars like to eat collard leaves too. Cabbage loopers and cutworms are two such entities that love to feed on your leafy vegetable plants. They both leave large holes in the leaves as they feed, as well as their excretions. If you see holes, check for feces or eggs laid by moths on the leaves. Often these can be controlled by handpicking. If the problem is not solved this way, neem oil or BT can prevent further larval damage.
Flea beetles are another pest that enjoy feasting on this vegetable plants’ delicious leaves. They are shiny, small black beetles that jump from place to place much like a flea. They tend to hang around during the warm growing season. They leave holes in leaves where they left off and can be controlled with soapy water traps. If they infest your greens, try a little spinosad or pyrethrin foliar pesticide weekly until the issue ceases.
The root-knot nematode can only be seen at the root level but will cause complete vegetable collapse if left unchecked. This pest causes galls on the roots of your collards as it chews on them. If your vegetables fail and the roots have small galls on them, you’re likely dealing with these microscopic pests. While there are commercial nematicides available, the best treatment is applying beneficial nematodes to combat the root-knot nematodes.
Diseases
Most of the fungal and bacterial diseases collard greens experience come from planting too close, improper watering, improper planting, or unusually moist conditions.
In some seasons, it may be worth cutting the stem of your plant at the base if the season has been too moist and downy mildew appears. Making the right decision at the right time can save this vegetable. Remember to keep collards at least 18 inches apart. If caught early enough that it’s not severe, remove any leaves with visible mildew and spray the rest of the plant with a copper fungicide.
White leaf spot and cercospora leaf spot need to be aggressively controlled early on or they will devastate your plant, the vegetables around it, and possibly your neighbor’s vegetables. Alternaria leaf spot may also cause damping-off in collard starts as well as leaf spot. Vigilance is key here in the wet spring and fall seasons. Some fungal leaf spots can be controlled with copper fungicide sprays, but some cannot be treated at all. Severe infections may mean removing the entire plant and disposing of it in a plastic bag to be taken to the landfill. Do not compost infected materials from plant diseases.
Brassicas are susceptible to clubroot caused by the pathogen Plasmodiophora brassicae. This disease can initially look like nematode damage, but the galls are much larger and in time the root will completely rot away. This causes plant death, and the spores of this fungus-like soil pathogen can linger in the soil for up to 20 years. Avoid planting brassicas in the affected area for 5-7 years after discovering plants with clubroot. Dispose of all remaining root material without composting. Recent research indicates that a specific bacteria, Bacillus amyloliquefaciens, may help plants to resist clubroot damage; this bacteria can sometimes be found in organic fertilizers with added bacteria and mycorrhizae, so check labels to see if yours contains it!
Frequently Asked Questions
Q: Do collard greens come back every year?
A: If you leave the root of a collard plant in your garden, they will return. They’re also vigorous seeders that happily return either once or twice a year depending on your USDA hardiness zone.
Q: How long does it take collard greens to grow?
A: Collard greens take one to two months from seed to harvest.
Q: Are collards easy to grow?
A: Collards are so easy to grow! The most important aspect of caring for collards once they’re established is pest control and watering. They need ample water, and many different pests like to eat their supple leaves.
