Hot Weather Speeds Up Vegetable Growth

By Scout Nelson

With daily highs in the 80s, vegetable crops are picking up speed following a slow spring. However, mid-season brings common nutrient challenges—especially in high-throughput crops like tomatoes.

Nutrient Deficiencies:

Yellowing older leaves can signal nitrogen deficiency. Foliar feeding with fish emulsion or blood meal helps. Tomatoes may also show magnesium deficiency—yellowing between green veins. High potassium soils often block magnesium uptake. Apply magnesium sulfate via drip irrigation or side dress if symptoms appear and confirm with a foliar test.

Postharvest Issues:

Improper storage can cause spoilage and chilling injury, especially in cucurbits. Review crop-specific storage guidelines to maintain quality after harvest. Over-chilled squash or potatoes lose marketability. Use UMN’s postharvest handling guide and DIY walk-in cooler design tips.

Crop Highlights:

Cucurbits are showing poor fruit set or misshapen fruit. Heat affects flower ratios, and rain may limit pollination. Remove bad fruit if labor allows to reduce disease risk. Fortunately, striped cucumber beetles are few this year, offering relief.

Broccoli and Cauliflower harvest is underway. Hollow stems are being seen occasionally, linked to hot weather, excess nitrogen, or boron deficiency. Though it doesn’t affect marketability, it can reduce shelf life.

Sweet Corn is beginning to appear on markets. High tunnel-grown corn leads the season, with field-grown not far behind.

Tomatoes are flowering, with high tunnel harvests beginning. Ensure each plant receives about 70–75 oz of water daily in hot conditions. Foliar diseases like early blight and septoria are appearing. Start fungicide applications at first signs of disease. Mulching, pruning, and proper spacing help reduce the spread. Organic and conventional options vary; always check product labels and greenhouse approval when needed.

Stay informed and proactive to maintain healthy crops and successful harvests throughout the summer.

Photo Credit:gettyimages-anilakkus