Yellow Squash in Zone 7B — Texas

Yellow squash is a winner in Texas gardens. It's delicious sauteed, grilled, or baked, and it's versatile enough to use in everything from casseroles to quick breads. Plus, there's nothing quite like the satisfaction of harvesting your own squash, especially when you can get two crops in our long growing season.

Texas weather can be unpredictable, with our brutal summer heat, occasional droughts, and the risk of hail. But with our long 255-day growing season and careful timing, you can definitely grow plenty of yellow squash.

Starting yellow squash indoors isn't usually necessary here in Texas, but it can give you a head start, especially if you're eager to get that first harvest as early as possible. Start seeds indoors from late February through mid March, about three weeks before you plan to transplant them outside.

Use seed trays with a good seed-starting mix, and keep them warm (around 70-75°F) and under grow lights. Bottom watering is a great way to keep the soil consistently moist without overwatering and risking damping-off. Given our early springs, indoor starting can help you take advantage of the initial warm-up.

Transplant your yellow squash seedlings outdoors from late March through early May, after the risk of frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week.

Choose a sunny spot and space the plants 24-36 inches apart. Keep an eye on the weather forecast – those late cold snaps can still surprise you, so be ready to cover your seedlings if needed.

Direct sowing is the easiest and most common way to grow yellow squash in Texas. Sow seeds directly into the garden from mid March through mid September. Yellow squash grows quickly from seed, so you can get multiple harvests.

Choose a spot with full sun and prepare the soil by amending it with compost. Make sure the soil temperature is at least 60°F before sowing. Plant seeds about an inch deep and space them 24-36 inches apart.

Yellow squash needs consistent and deep watering, especially in the Texas heat. Aim to water at the base of the plant to avoid wetting the foliage, which can lead to fungal diseases in our variable humidity. Water in the morning so the leaves have time to dry during the day.

During the spring and fall, when temperatures are milder, water deeply once or twice a week, providing about 1-2 inches of water. In the peak of summer, you might need to water every day, especially if it's dry. Stick your finger about two inches into the soil – if it feels dry, it's time to water. Unpredictable rainfall means you'll need to check soil moisture regularly.

Signs of underwatering include wilting leaves and slow growth. Overwatering can cause yellowing leaves and root rot. A good layer of mulch can help retain moisture and keep the soil cool, which is especially helpful during our hot summers.

You can expect your first harvest of yellow squash from early May through mid November, about 50 days after planting. Harvest the squash when it's 6-8 inches long and the skin is still tender enough to dent with your fingernail.

Use a sharp knife or pruners to cut the squash from the plant, being careful not to damage the vine. Regular harvesting encourages the plant to produce more squash, so check your plants every few days.

As the first frost approaches in mid- November, harvest any remaining squash, even if they're a little smaller. They may not ripen much off the vine, but you can still use them in cooking.

Here are some common problems you might encounter growing yellow squash in Texas:

Squash Vine Borer

• What it looks like: Wilting vines, holes near the base of the stem, and sawdust-like frass (larval excrement) near the holes.
• What causes it: Squash vine borer moths lay eggs on the stems, and the larvae burrow into the vine, feeding on the plant tissue.
• How to fix/prevent it: Wrap the base of the stems with aluminum foil or row covers to prevent the moths from laying eggs. Check stems regularly for eggs and remove them. Inject Bacillus thuringiensis (Bt) into the stem to kill the larvae.

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves, stems, and sometimes fruit. Leaves curl, yellow, and die. Reduces plant vigor.
• What causes it: Various fungi that thrive in warm days, cool nights, and moderate humidity. Dry leaf surfaces actually favor it (unlike most fungi).
• How to fix/prevent it: Improve air circulation through spacing and pruning. Remove affected leaves. Neem oil or potassium bicarbonate sprays help. Milk spray (1 part milk to 9 parts water) is surprisingly effective. Plant resistant varieties.

Squash Bugs

• What it looks like: Gray-brown shield-shaped bugs on leaf undersides. Bronze egg clusters on leaves. Wilting leaves that turn brown and crispy.
• What causes it: Sap-sucking insects that inject toxin while feeding. Adults overwinter in garden debris and emerge in spring.
• How to fix/prevent it: Hand-pick adults and crush egg clusters. Board traps (adults hide under boards at night — flip and destroy in morning). Neem oil spray. Remove plant debris in fall. Companion plant with nasturtiums.

Blossom End Rot

• What it looks like: Sunken, dark brown or black leathery patch on the bottom (blossom end) of fruit. Often affects first fruits of the season.
• What causes it: Calcium deficiency caused by inconsistent watering. Not a disease — it's a nutrient uptake problem triggered by drought/flood cycles.
• How to fix/prevent it: Water consistently (the single most effective fix). Mulch heavily to maintain even soil moisture. Don't over-fertilize with nitrogen. Calcium sprays help marginally. Remove affected fruit.

Texas Specific Challenges: The hot-to-extreme heat, variable humidity, and unpredictable rainfall in Texas can exacerbate these problems. Consistent watering is key to preventing blossom end rot and keeping your plants healthy enough to withstand pests and diseases. Fire ants can also be a nuisance, so be sure to control them in your garden.

Companion planting can really help your yellow squash thrive here in Texas. Corn provides a natural trellis for beans, which in turn fix nitrogen in the soil, benefiting the squash. Radishes help deter squash vine borers, and marigolds repel nematodes and other pests.

Avoid planting yellow squash near potatoes, as they compete for nutrients. Also, steer clear of brassicas (like cabbage and broccoli), as they can attract pests that also affect squash.