Yellow Squash in Zone 7B — Southeast

Yellow squash is a fantastic addition to any Southeast garden. Its mild, slightly sweet flavor makes it incredibly versatile in the kitchen, perfect for everything from summer casseroles to simple sautéed sides. Plus, there's nothing quite like the satisfaction of harvesting armfuls of these sunny yellow veggies from your own backyard during our long summer growing season.

While we deal with our share of challenges like humidity and those pesky Japanese beetles, the good news is that yellow squash thrives in our warm, wet summers. With a 235-day growing season, you'll have plenty of time to get multiple harvests. Careful planning and attention to watering will set you up for success.

Starting yellow squash indoors is an option, but honestly, direct sowing is typically easier in our climate. If you're itching to get a head start, though, you can start seeds indoors from early to late March, about three weeks before you plan to transplant them outside.

Use seed trays with a good seed-starting mix, and make sure they're in a warm spot with plenty of light – a sunny windowsill or under grow lights works well. Bottom watering is key to prevent damping off; just set the tray in a shallow dish of water and let the soil soak it up from the bottom. With our moderate spring weather, you don't have to rush, but getting a small head start can extend your harvest.

Transplanting yellow squash outdoors should be done from early April through mid May, once the danger of frost has passed. Before you move your seedlings outside permanently, be sure to harden them off. This means gradually exposing them to outdoor conditions for about a week, starting with just an hour or two of shade and increasing the time and sun exposure each day.

When transplanting, space the plants about 24-36 inches apart to give them plenty of room to grow. Keep an eye on the weather forecast; those late-season cold snaps can still happen. If a frost is predicted, cover your transplants to protect them.

Direct sowing is the easiest and most common way to grow yellow squash in the Southeast. You can sow seeds directly into the garden from late March through early September, giving you a long window for succession planting and multiple harvests.

Choose a spot with full sun and well-drained soil. Our clay soil can be challenging, so amend it with plenty of compost before planting. The soil temperature should be at least 60°F for good germination. Plant seeds about an inch deep and space them 24-36 inches apart. Yellow squash grows quickly from seed, so you'll see seedlings emerge in just a few days.

Yellow squash needs consistent watering, especially during our hot, humid summers. Aim to water deeply at the base of the plant, providing about 1-2 inches of water per week, depending on rainfall.

The "finger test" is a good way to check soil moisture: stick your finger into the soil about 2 inches deep. If it feels dry, it's time to water. Water in the morning to allow the foliage to dry before nightfall, which helps prevent fungal diseases in our humid climate. During periods of heavy rainfall, you may not need to water at all.

Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to root rot, indicated by yellowing leaves and mushy stems. Mulching around the plants with straw or pine straw helps retain moisture and keeps the soil cooler.

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

Use a sharp knife or pruning shears to cut the squash from the vine, leaving a short stem attached. Avoid pulling or twisting, which can damage the plant. Regular harvesting encourages continued production. Check your plants every couple of days during peak season.

As the first frost approaches in early November, harvest any remaining squash, even if they're a bit smaller than usual. While they won't ripen off the vine, you can still use them in cooking.

Yellow squash can be susceptible to a few common problems in the Southeast:

Squash Vine Borer

• What it looks like: Wilting vines that suddenly collapse, often with small holes near the base of the plant and sawdust-like frass (excrement).
• What causes it: Moth larvae bore into the stems and feed on the plant's tissue, disrupting water and nutrient flow.
• How to fix/prevent it: Wrap stems with foil or nylon stockings to prevent egg-laying. Inject Bacillus thuringiensis (Bt) into the stem near the entry hole to kill the borers. Remove and destroy infested plants.

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves, stems, and sometimes fruit. Leaves curl, yellow, and die.
• What causes it: Various fungi that thrive in warm days, cool nights, and moderate humidity. Dry leaf surfaces actually favor it.
• 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.

Southeast Specific Challenges: Our hot, humid summers and frequent afternoon thunderstorms create ideal conditions for fungal diseases like powdery mildew. Be proactive with watering practices (morning watering, avoid overhead watering) and ensure good air circulation to minimize these problems. Japanese beetles can also be a nuisance, so consider using row covers or hand-picking them off plants.

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

Avoid planting yellow squash near potatoes, as they compete for the same nutrients. Also, keep them away from brassicas (like cabbage and broccoli), as they can attract similar pests and diseases. Proper spacing and good air circulation are key to preventing problems, especially in our humid climate.