Yellow Squash in Zone 8A — Southeast

Yellow squash is a staple in Southern cooking for good reason. Its mild flavor and versatility make it a welcome addition to any summer meal, whether grilled, sautéed, or baked into a casserole. Plus, there’s real satisfaction in harvesting armfuls of these sunny yellow beauties from your own backyard throughout our long summer.

Our hot and humid climate can present some challenges, but with a little planning and attention, you can easily grow a bumper crop of yellow squash. Our extended 245-day growing season gives you plenty of time to get multiple harvests.

Starting yellow squash indoors is possible, but honestly, direct sowing is the way to go for most of us in the Southeast. However, if you're itching to get a head start, you can start seeds indoors from early to late March, about three weeks before you plan to transplant them.

Use seed trays or small pots filled with a good seed-starting mix. Keep them warm and provide plenty of light, either with a grow light or a sunny windowsill. Bottom watering helps prevent damping-off, so set the trays in a shallow pan of water and let the soil soak it up from the bottom. Our moderate spring temperatures mean you don't have to rush, but this method can give you a jump on the season.

Transplanting yellow squash seedlings outdoors should happen from late March through early May. Before you put them in the ground, harden them off by gradually exposing them to outdoor conditions for about a week.

Plant them 24-36 inches apart in well-drained soil. Keep an eye on the weather forecast – a late frost can still happen, so be prepared to cover your seedlings if necessary.

Direct sowing is the preferred method for yellow squash in the Southeast. The seeds germinate quickly in our warm soil and the plants take off like crazy. Sow seeds from late March through mid September for a continuous harvest.

Choose a spot in full sun with well-drained soil. Amend our often heavy clay soil with compost or other organic matter to improve drainage and fertility. Plant seeds about an inch deep, spacing them 24-36 inches apart. Yellow squash grows quickly from seed, so direct sowing is definitely the easiest route.

Yellow squash needs consistent watering, especially during our hot and humid summers. Aim for deep watering at the base of the plant, avoiding overhead watering as much as possible to minimize fungal disease.

During the spring and fall, when temperatures are milder and we tend to get more rain, check the soil moisture regularly using the finger test – stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water. In the heat of summer, you'll likely need to water every other day, providing about 1-2 inches of water per week.

Pay attention to your plants. Wilting leaves, even in the morning, indicate underwatering. Yellowing leaves or mushy stems can be a sign of overwatering. Mulching around your squash plants with straw or pine straw helps retain moisture and suppress weeds, a big plus with our long growing season.

You can expect your first harvest of yellow squash from mid May through mid November, about 50 days after planting. The best time to harvest is when the squash are 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. Harvesting regularly encourages continued production.

As our first frost approaches in mid- November, harvest all remaining squash, even if they're a little smaller than usual. They may not ripen much more on the vine, but they're still delicious!

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

Squash Vine Borer

• What it looks like: Wilting vines that suddenly collapse, often with small holes near the base of the stem. You might see a sawdust-like substance near the holes.
• What causes it: Squash vine borers are moth larvae that burrow into the stems of squash plants and feed on the tissue.
• How to fix/prevent it: Wrap the base of the stems with foil or netting to prevent the moths from laying eggs. If you see signs of infestation, you can try to carefully slit the stem open and remove the borer, then cover the stem with soil to encourage rooting.

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: Powdery mildew is a fungal disease that thrives 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.

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: Squash bugs are 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.

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: Blossom end rot is a calcium deficiency caused by inconsistent watering. It's not a disease, but a nutrient uptake problem triggered by drought/flood cycles.
• How to fix/prevent it: Water consistently. Mulch heavily to maintain even soil moisture. Don't over-fertilize with nitrogen.

Southeast Specific Challenges: Our hot and humid climate creates the perfect conditions for fungal diseases like powdery mildew. The humidity also makes it crucial to water at the base of the plants and provide good air circulation. The long summer means Japanese beetles can be a problem, so be prepared to implement control measures if necessary. And don't forget about the deer – they love squash plants, so fencing may be needed.

Companion planting can really boost your yellow squash crop here in the Southeast. Corn provides shade and support for climbing beans, which in turn fix nitrogen in the soil, benefiting the squash. Radishes can help deter squash vine borers. Marigolds are great for repelling 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.