How to Create a Year-Round Planting Calendar for Greenhouses?

Determining Climate Zones and Planting Seasons

To create a greenhouse planting calendar, first, identify the climate zone and corresponding planting seasons for your area. In temperate climates, greenhouses can extend the growing season from March to November. Divide the growing season into four planting periods: spring (March-May), summer (June-August), autumn (September-November), and winter (December-February). For example, in a USDA Hardiness Zone 6b, the planting calendar might look like this: spring crops (broccoli, cauliflower) planted in late March, summer crops (tomatoes, peppers) planted in late May, autumn crops (lettuce, spinach) planted in late August, and winter crops (kale, spinach) planted in late October.

Planning for Specific Plant Requirements

Next, research the specific requirements for each plant species, including optimal temperature, light, and humidity levels. For instance, seedlings of tomatoes and peppers require temperatures between 70-80°F (21-27°C) and 12-14 hours of light per day. In contrast, lettuce and spinach thrive in cooler temperatures (50-60°F or 10-15°C) with fewer hours of direct sunlight. Consider using supplemental lighting or temperature control systems in the greenhouse to meet these requirements.

Season Extension Techniques

To extend the growing season and make the most of your greenhouse, consider using season extension techniques such as cold frames, row covers, and hoop houses. Cold frames can warm the soil by 10-20°F (5-10°C) and extend the growing season by 2-4 weeks. Row covers can provide additional light and warmth during the winter months, while hoop houses can extend the growing season by several months.