Collard Greens in Zone 7B — Desert Southwest

Collard Greens are a workhorse in the desert garden. They bring a slightly bitter, earthy flavor that's fantastic braised, sauteed, or even added to soups. Plus, they're surprisingly cold-hardy, which means you can harvest them well into our long fall and even through mild winters here.

Desert gardening definitely has its hurdles, like extreme heat and alkaline soil. But with careful timing, especially taking advantage of our two growing seasons and 245-day season, you can definitely grow a successful patch of Collard Greens.

Starting Collard Greens indoors gives you a head start, but it's not strictly necessary here. If you're itching to get going early, aim to start your seeds indoors from early February through early March. That's about four weeks before you'd want to put them in the ground.

Use seed trays with a good seed-starting mix. Keep them warm and under grow lights. Bottom watering is key to avoid damping off. Given our very-early spring character, starting indoors helps you get ahead of the heat.

Transplanting Collard Greens seedlings outdoors should happen from mid March through mid April. Before you put them in the ground, you'll need to harden them off. Give them about a week of gradually increasing outdoor exposure.

Space your plants 18-24 inches apart. At transplant time, keep an eye out for late frosts. It’s rare, but that early warmth can sometimes trick you. Protect your seedlings if needed.

Direct sowing Collard Greens is a perfectly viable option in our climate. Sow seeds directly into the garden from early March through mid August. The soil needs to be at least 60°F for good germination.

Prepare your soil well, amending with compost to improve drainage and fertility. Space your seeds 18-24 inches apart. Direct sowing works great for succession planting to extend your harvest.

Collard Greens need consistent moisture, especially here in the desert. While they're more heat-tolerant than some other brassicas, they still suffer in our extreme heat and arid conditions if they dry out. Aim for even moisture to keep those leaves tender.

During the spring and fall growing seasons, water deeply about 1-2 times per week, providing around 1 inch of water each time. In the peak of summer, you'll likely need to water every day, maybe even twice on the hottest days, to deliver 2 inches of water. Stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water.

Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases. Overhead watering is fine during the monsoon season, but avoid it during periods of high heat. Wilting leaves are a sign of underwatering, while yellowing leaves could indicate overwatering. A good layer of mulch, like shredded bark or straw, helps retain moisture and regulate soil temperature, which is crucial here.

You can expect your first harvest of Collard Greens from mid May through late November, depending on when you planted. Look for lower leaves that are 10-12 inches long. These are usually ready to pick.

Harvest by cutting the outer leaves with a sharp knife or shears, leaving the top rosette intact. This allows the plant to continue producing. Don't be afraid to harvest regularly; it encourages new growth.

As our first frost approaches in mid- November, you can harvest the entire plant or cover it with a frost blanket to extend the harvest a bit longer. The leaves actually taste sweeter after a light frost!

Here are some common problems you might encounter with Collard Greens in the Desert Southwest:

Cabbage Worms

• What it looks like: You'll see smooth green caterpillars munching on leaves, leaving irregular holes and dark green droppings behind. White butterflies flitting around are another clue.
• What causes it: The larvae of those cute white cabbage butterflies are the culprits. They love warm weather, and we definitely have that!
• How to fix/prevent it: Bt spray is your best friend. Use floating row covers to keep the butterflies from laying eggs. You can also handpick the caterpillars. Interplanting with herbs like thyme and sage helps 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 and curled or distorted new growth.
• What causes it: These sap-sucking insects reproduce rapidly, especially in warm weather. Ants often "farm" them for the honeydew.
• How to fix/prevent it: Blast them off with a strong stream of water. Encourage ladybugs and lacewings, which are natural predators. Insecticidal soap works well for heavy infestations. Avoid over-fertilizing with nitrogen.

Cabbage Loopers

• What it looks like: Pale green caterpillars that move in a looping motion. They chew large holes in leaves, often leaving just the veins.
• What causes it: Similar to cabbage worms, these are the larvae of moths that lay eggs on your plants.
• How to fix/prevent it: Bt spray is effective. Handpicking also works well. Encourage natural predators like birds and parasitic wasps.

Downy Mildew

• What it looks like: Yellow patches on the upper leaf surface with fuzzy gray-purple growth on the undersides. Leaves eventually turn brown and die from the bottom up.
• What causes it: This fungal disease thrives in cool, humid conditions. Monsoon season can definitely create the right environment.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation around your plants. Water at the base, not overhead. Copper-based fungicides can help prevent the spread.

Desert Southwest Specific Challenges: Our extreme heat can stress plants, making them more susceptible to pests and diseases. The arid climate means you need to be vigilant about watering. Even though it's arid, monsoon season can create humidity spikes that encourage fungal problems. Alkaline soil can also affect nutrient availability, so amend your soil with compost regularly.

Companion planting can really boost your Collard Greens game. Onions and garlic help deter pests with their strong scent. Beets are good neighbors because they don't compete for the same nutrients. Potatoes can provide some shade, which is helpful during our hot summers. Dill attracts beneficial insects that prey on pests.

Avoid planting strawberries or tomatoes near your Collard Greens. Strawberries can attract slugs and snails, which will also munch on your greens. Tomatoes can compete for nutrients and attract pests that might also bother your Collard Greens.