Home gardeners nationwide face a familiar summer question: After months of watering, weeding and tending their plants, how can they tell when produce is ready to harvest? Picking even a day early or late can mean the difference between a perfect ear of corn and one picked too soon, or a juicy tomato and a mealy disappointment.

To help take the guesswork out of harvesting, the National Garden Bureau, a nonprofit organization promoting home gardening, has released a comprehensive new harvest guide: “Ripe and Ready? How to Know When to Harvest Homegrown Fruits and Veggies.”

Packed with tips from North America’s plant breeders, the new guide covers 16 warm-season favorites, from hidden subterranean crops such as sweet potatoes to tricky vine-ripened melons.

“We’ve all walked into the garden to find a zucchini that somehow turned into a baseball bat overnight,” Diane Blazek, executive director, said in a news release. “Our goal with this guide is to give home growers clear visual and sensory cues so they can harvest at the precise moment of peak flavor, texture and nutritional value.”

Highlights from the harvest guide include:

• The morning golden hour: For maximum crispness and sugar content, harvest produce in the early morning just after the dew dries. Avoid picking during peak heat, which causes harvested fruits and vegetables to wilt rapidly.

• The hidden crop cues: For crops hidden beneath husks or soil, rely on secondary signs. Corn is ready at the milk stage, when silks are full, dry and brown. Watermelons signal readiness when the tendril closest to the fruit dries up and the underbelly turns from white to creamy yellow.

• The breaker-stage trick for tomatoes: Gardeners battling pests or summer rainstorms don’t need to leave tomatoes on the vine until they are fully red. Tomatoes harvested at the breaker stage — when green skin first blushes pink or yellow — will finish ripening indoors on a countertop without losing flavor, color or nutrients.

• Continuous yields: Crops such as bush beans, cucumbers and basil respond directly to harvest frequency. The more regularly gardeners pick, the more the plant is stimulated to produce.

The guide highlights plant varieties developed by the National Garden Bureau’s national network of breeders, growers and distributors. From compact patio varieties designed for container gardens, such as Patio Baby eggplant and Quick Snack cucumbers, to All-America Selections winners such as Century Star watermelon and Dragonfly peppers, the guide helps consumers match harvest timing to specific plant genetics.

The complete guide, “When to Harvest Vegetables and Fruits,” is available at ngb.org/when-to-harvest-vegetables-and-fruits/

Founded in 1920, the National Garden Bureau is a nonprofit organization whose mission is to share inspirational, reliable and expert gardening information to educate, motivate and inspire home gardeners across North America. Members include plant breeders, seed distributors, growers and garden centers.