Collard Greens in Zone 7A — Desert Southwest

Collard greens are a true taste of the South, and surprisingly, they thrive in our Desert Southwest gardens too. Their slightly bitter, earthy flavor is fantastic braised, sauteed, or even added to soups, and there's nothing quite like the satisfaction of harvesting your own homegrown greens well into the fall. Don't let our extreme heat scare you off—with some smart timing and attention to watering, you can enjoy a bountiful harvest.

Our 230-day growing season gives you a lot of flexibility, and collards are much more forgiving than you might think. The key is to work *with* the seasons, planting at the right time to avoid the worst of the summer heat. With proper planning, you can have collards even when other crops are struggling.

Starting collard greens indoors gives you a head start, but honestly, it's not always necessary here. If you're itching to get growing early, or want to ensure a harvest before the extreme heat hits, go for it!

Start your seeds indoors from mid February through mid March, about four weeks before you plan to transplant. Use seed trays or small pots with a good seed-starting mix, and keep them warm and well-lit—a sunny windowsill or grow light works well. Bottom watering helps prevent damping off, which can be a problem in our very-early spring warmth.

Transplanting is best done in late March through late April, after the last frost. Before you move them outside, harden off your seedlings by gradually exposing them to outdoor conditions for about a week.

Space your collard green plants 18-24 inches apart to give them plenty of room to grow. Keep an eye on the weather—those late spring temperature swings can be tough on young transplants.

Direct sowing collard greens is a perfectly viable option, and often easier than starting indoors. You can direct sow from mid March through mid August, giving you a long window of opportunity.

Make sure your soil is well-prepared and the soil temperature is consistently above 60°F. Plant seeds about ½ inch deep, and thin seedlings to 18-24 inches apart once they emerge. Direct sowing works well with our monsoon moisture, as long as you keep the soil consistently moist until germination.

Watering is crucial for collard greens, especially in our arid Desert Southwest climate. While they're more heat-tolerant than other brassicas, consistent moisture is key to preventing tough, bitter leaves.

During the cooler spring and fall months, aim for about 1 inch of water per week, either from rainfall or irrigation. As the extreme heat of summer sets in, increase that to 2 inches per week, or even more if your plants show signs of stress. Use the "finger test"—stick your finger about 2 inches into the soil. If it feels dry, it's time to water. Water deeply at the base of the plants to avoid wetting the leaves, which can lead to fungal problems in our monsoon season.

Signs of underwatering include wilting leaves and slow growth, while overwatering can cause yellowing leaves and root rot. A layer of mulch around your plants helps retain moisture and regulate soil temperature, which is especially helpful during our scorching summers.

You can expect your first harvest of collard greens starting in late May and continuing through mid November. Collards are ready to harvest about 75 days after planting.

Harvest the lower leaves when they reach 10-12 inches long, leaving the top rosette to continue growing. The flavor of collards actually sweetens after a light frost, so don't be afraid to leave them in the garden as long as possible. As the first frost approaches in early November, harvest any remaining large leaves to prevent them from being damaged.

Here are some common problems you might encounter with collard greens in the Desert Southwest:

Cabbage Worms

• What it looks like: Smooth green caterpillars chewing irregular holes in leaves, leaving dark green droppings behind. You might also see white cabbage butterflies fluttering around.
• What causes it: These are the larvae of white cabbage butterflies, and they can go through multiple generations in our long, warm growing season.
• How to fix/prevent it: Bt spray is very effective against cabbage worms. Floating row covers can prevent the butterflies from laying eggs. You can also handpick the caterpillars or interplant with aromatic herbs like thyme and sage to deter them.

Aphids

• What it looks like: Clusters of tiny green, black, or white insects on stems and leaf undersides. You might also notice sticky honeydew residue and curled or distorted new growth.
• What causes it: Aphids are sap-sucking insects that reproduce rapidly, especially in warm weather. Ants often "farm" them for their honeydew.
• How to fix/prevent it: A strong spray of water can knock aphids off your plants. Encourage natural predators like ladybugs and lacewings. Insecticidal soap or neem oil can be used for heavy infestations. Avoid over-fertilizing with nitrogen, as this attracts aphids.

Cabbage Loopers

• What it looks like: Similar to cabbage worms, but these caterpillars move in a looping motion. They also chew holes in leaves and can defoliate plants.
• What causes it: Cabbage loopers are another type of caterpillar that thrives in warm weather.
• How to fix/prevent it: Use Bt spray, handpick caterpillars, or use floating row covers.

Downy Mildew

• What it looks like: Yellow patches on the tops of leaves with fuzzy gray-purple growth on the undersides. Leaves will eventually brown and die from the bottom up.
• What causes it: Downy mildew is a fungal disease that spreads in cool, humid conditions.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation around your plants. Water at the base to avoid wetting the leaves. Copper-based fungicides can be used for prevention.

Desert Southwest Specific Challenges: The extreme heat and arid humidity of our region can stress collard greens, making them more susceptible to pests and diseases. Sunscald can also be a problem, especially for young plants. Consistent watering and afternoon shade during the hottest months are essential for success.

Companion planting can help your collard greens thrive in the Desert Southwest. Onions and garlic are great companions because their strong scent repels many pests. Beets and potatoes are also good neighbors, as they don't compete for the same nutrients. Dill attracts beneficial insects that prey on pests like aphids and cabbage worms.

Avoid planting collard greens near strawberries or tomatoes. Strawberries are susceptible to some of the same fungal diseases as collards, and tomatoes can stunt the growth of collards.