Collard Greens in Zone 10A — Desert Southwest

Collard greens thrive in our mild winters and offer a delicious, slightly bitter flavor that complements Southwestern cuisine perfectly. They're incredibly versatile – you can sauté them, add them to soups, or even use them as wraps. Plus, there's a real satisfaction in harvesting fresh greens from your own garden during our cooler months.

Desert gardening definitely has its challenges, with our extreme heat and alkaline soil. But don't worry, with careful timing and a few tricks, you can absolutely enjoy a bountiful harvest of collard greens during our two growing seasons. Our long 339-day growing season gives you plenty of opportunities to get it right.

Starting collard greens indoors is an option, especially if you want a head start. Aim to sow seeds mid-December through early January, about four weeks before you plan to transplant them outside. This helps you get ahead of any late cold snaps.

Use seed trays or small pots filled with well-draining potting mix. Keep the soil consistently moist, using bottom watering to prevent damping off. Place the trays in a warm spot with plenty of light – a sunny windowsill or under grow lights will work well given our very-early spring character.

Transplant your collard greens seedlings outdoors mid-January through mid-February. Before you plant, harden them off by gradually exposing them to outdoor conditions for about a week. This prevents shock from our intense Desert Southwest sun.

Space the seedlings 18-24 inches apart in well-amended soil. Even in January and February, be mindful of potential temperature swings. If a cold snap is predicted, be ready to cover the young plants with frost cloth.

Direct sowing is a simple and effective way to grow collard greens here in the Desert Southwest. You can sow seeds early January through late September. This long window takes advantage of our two growing seasons.

Prepare your garden bed by loosening the soil and mixing in compost. Sow seeds about ½ inch deep and keep the soil consistently moist until they germinate. Thin the seedlings to 18-24 inches apart once they have a few true leaves. Just be sure to provide adequate shade during the hotter months to prevent bolting.

Collard greens need consistent moisture to produce tender, flavorful leaves, but they don't like soggy soil. In our Desert Southwest climate, this means paying close attention to your watering schedule.

During the cooler months (late fall through early spring), aim for about 1 inch of water per week, either from rainfall or irrigation. As temperatures rise in the spring and approach our extreme summer heat, increase watering to 2-3 inches per week. The finger test is your friend: stick your finger about 2 inches 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, even in our arid climate. Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to yellowing leaves and root rot. A layer of mulch around your plants helps retain moisture and regulate soil temperature, which is crucial in our desert conditions.

You can expect your first harvest of collard greens late March through early January, about 75 days after planting. Look for the lower leaves to be 10-12 inches long and a deep green color.

To harvest, simply snip off the outer leaves near the base of the plant, leaving the top rosette intact. This allows the plant to continue producing new leaves throughout the season. Harvest regularly to encourage continued growth. The flavor of collard greens actually sweetens after a frost, so don't be afraid to leave them in the garden as long as possible.

As our first frost approaches in late December, harvest any remaining leaves. You can blanch and freeze them for later use, or enjoy them in a hearty winter stew.

Here are some common problems you might encounter growing 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 butterflies fluttering around.
• What causes it: The larvae of those white cabbage butterflies. They thrive in our long, warm growing season, leading to multiple generations.
• How to fix/prevent it: Bt spray is your best friend. Also, use floating row covers to keep the butterflies from laying eggs. Handpicking works too. 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'll also notice sticky honeydew and curled or distorted new growth.
• What causes it: These sap-sucking insects multiply rapidly in warm weather. Ants can even "farm" them for their 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 for heavy infestations, and neem oil can help systemically. Avoid over-fertilizing with nitrogen, which attracts them.

Cabbage Loopers

• What it looks like: Similar to cabbage worms, but these are pale green with white stripes and move in a looping motion. They also chew holes in leaves.
• What causes it: These are another type of caterpillar that loves brassicas. Like cabbage worms, they have multiple generations in our warm climate.
• How to fix/prevent it: Bt spray is effective. Handpicking is also an option. Use row covers to prevent moths from laying eggs.

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: A pathogen that spreads in cool, humid conditions. While we're generally dry, monsoon moisture can create favorable conditions.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation by spacing plants properly. Water at the base, never overhead. Copper-based fungicides can help prevent it.

Desert Southwest Specific Challenges: Our extreme heat can stress collard greens, making them more susceptible to pests and diseases. Sunscald can also be a problem, especially for young plants. Consistent watering is crucial to combat our arid humidity and prevent bolting. Even with monsoon moisture, our alkaline soil can affect nutrient availability, so amend your soil with plenty of compost.

Companion planting can really help your collard greens thrive in the Desert Southwest. Onions and garlic are great companions because their strong scent deters many pests that bother collards. Beets and potatoes are also good choices, as they don't compete for the same nutrients in the soil. Dill attracts beneficial insects like ladybugs and lacewings, which prey on aphids and other pests.

Avoid planting strawberries or tomatoes near your collard greens. Strawberries can attract slugs and snails, which may then move on to your collards. Tomatoes are susceptible to fungal diseases that can spread to your collard greens, especially during our monsoon season.