What to Grow in New York Greenhouses Each Season

Growing in a New York greenhouse gives you control over temperature, humidity, and season length in a state with wide climate variation. Whether you are in Long Island or the Adirondacks, understanding which crops perform best in each season and how to manage the environment will maximize production and quality. This guide breaks down season-by-season recommendations, environmental targets, variety and crop choices, and practical management actions you can take to get reliably productive greenhouses year-round.

How to read this guide: climate, greenhouse type, and scale

New York spans USDA zones roughly 3b to 7b. Most commercial and hobby greenhouses in the state are unheated, minimally heated, or fully heated. Recommendations below assume a typical glass or poly greenhouse with at least minimal frost protection and the option to add supplemental heat and lighting. If you have only a cold frame or a passive hoop house, focus on the cool-season and overwinter tips. If you have a heated greenhouse with supplemental lighting, you can carry warm-season fruiting crops through the winter.

Key environmental targets (practical numbers)

Day/night temperature targets by crop type:

• Cool-season leafy greens and brassicas: day 50-68 F, night 40-50 F.
• Warm-season fruiting crops (tomato, pepper, cucumber): day 70-85 F, night 60-70 F.
• Herbs: 65-80 F day, 55-65 F night (varies by herb).

Light and hours:

• Leafy crops need 10-14 hours of good light; supplement to 12-16 hours in winter.
• Fruiting crops perform best with 14-18 hours of light if grown under supplemental lighting during short winter days.

Humidity:

• Aim for 50-70% relative humidity daytime; lower humidity (45-55%) helps reduce fungal disease during the night.

Soil and fertilizer basics:

• Use a well-draining greenhouse mix: 50-70% peat or coir, 20-40% perlite or vermiculite, and 10% compost or aged bark for structure.
• Fertilize leafy greens with a higher nitrogen ratio; fruiting crops need balanced N-P-K with elevated potassium during fruit set.

Sanitation and pest prevention:

• Clean benches and remove plant debris weekly. Quarantine new plants for at least two weeks.
• Scout for aphids, whiteflies, thrips, and fungus gnats; use sticky traps and beneficial insects (lacewings, parasitic wasps) or targeted organic sprays only when necessary.

Practical takeaway: measure and record temperatures and humidity daily. Small investments in a thermometer/hygrometer and a grow light timer will pay off in fewer crop failures.

Spring: get an early jump on cool and warm crops

Spring is when the greenhouse returns the most value to New York growers. You can start many crops earlier than outdoor planting dates and produce high-value harvests.
What to grow in spring:

• Cool-season transplants: broccoli, cabbage, cauliflower, kohlrabi.
• Early leafy greens: lettuce, arugula, spinach, mustard greens, tatsoi.
• Early herbs: parsley, cilantro, chives.
• Warm-season seedlings: tomato, pepper, eggplant (start seeds in late winter).

Practical details:

• Sow broccoli, cauliflower, and cabbage indoors 6-8 weeks before outdoor transplant dates — in New York that means starting seeds in late February to early March for spring greenhouse production.
• Lettuce and other salad greens can be sown successively every 1-2 weeks from late February through May for continuous harvest.
• Keep day temps for transplants around 65-70 F and night temps 50-55 F to produce sturdy seedlings without being leggy.
• Ventilate on sunny spring days to prevent overheating; use shade cloth when temperatures exceed 75 F.

Spring pest and disease notes:

• Aphids and whiteflies can explode on tender spring growth. Use insecticidal soaps and encourage natural predators.
• Start a sanitation program now — remove any overwintering debris and clean benches to reduce fungal inoculum.

Summer: maximize fruiting crops and succession plantings

Summer in a greenhouse can be hotter and more humid than outdoors. Good climate control is essential to avoid heat stress, blossom drop, and disease.
Best summer crops:

• Tomatoes (determinate for short-season, indeterminate for continuous harvest).
• Cucumbers (vine or bush types), trellised.
• Peppers and eggplants.
• Basil, summer herbs, sweet corn in large structures.
• Heat-tolerant greens: New Zealand spinach, Malabar spinach, amaranth.

Climate management:

• Use shade cloth (30-50%) during mid-summer to reduce light intensity and heat load.
• Ventilation plus circulating fans keep foliage dry and reduce fungal risk. Aim for air exchange rates that replace greenhouse air every 1-5 minutes on hot days.
• Evaporative cooling or wet-pad systems are effective in larger structures; small hobby greenhouses may rely on shade and ventilation.

Pollination and trellising:

• Provide pollinators (bumblebee hives) for tomatoes and peppers in enclosed greenhouses, or hand-pollinate flowers in small operations.
• Train tomatoes and cucumbers on trellises; use clips and string ties to prevent fruit rot and improve light penetration.

Irrigation and nutrition:

• Switch to more frequent, lighter irrigations in summer; avoid saturated soil that encourages root diseases.
• Fertilize fruiting crops weekly with a balanced feed, increasing potassium during fruit set to improve flavor and shelf life.

Fall: extend harvests and plant second crops

Fall is a sweet spot for greenhouses: you can keep summer crops late and also establish winter greens and brassicas for fall and winter harvest.
Fall crop priorities:

• Continue harvests of tomatoes and cucumbers until light and temps decline.
• Seed and transplant fall brassicas for late fall and early winter harvest: kale, collards, Brussels sprouts.
• Plant fast-maturing salad greens and spinach in late summer/early fall to take advantage of cooler growth — they produce tender leaves and resist bolting.
• Spinach sown in August-September will be productive into November in a protected greenhouse.

Seasonal actions:

• Start reducing nighttime heating gradually as daylight shortens to harden crops before winter.
• Mulch or add thermal mass (barrels of water painted black) to moderate nighttime temperature swings.
• Consider row covers or double-layer curtains for additional frost protection if you plan to keep sensitive crops later into fall.

Fall pest notes:

• Check for late-season aphid outbreaks on brassicas and kale — use biocontrols where possible.
• Remove spent summer crops promptly to reduce shelter for pests and pathogens.

Winter: choose hardy crops or invest in heat and light

Winter greenhouse production in New York is a choice between growing only the hardiest crops with minimal heat or running a heated, lighted greenhouse for high-value warm-season production.
Cold-tolerant winter crops (low- or unheated greenhouse):

• Winter-hardy greens: winter spinach, mache (corn salad), winter lettuces, mizuna.
• Kale and collards: many varieties continue to produce at 40-55 F.
• Root crops for storage: carrots, beets, and baby radishes in beds with frost protection.
• Microgreens and sprouts: high turnover, minimal heating, high value.

Heated winter production (if you have heat and supplemental lighting):

• Tomatoes, cucumbers, peppers — choose varieties bred for greenhouse production and short internodes.
• Leafy greens and herbs year-round using hydroponics or bench production under LEDs.
• High-value crops: culinary herbs (basil, cilantro), edible flowers, and specialty greens.

Winter environmental specifics:

• If growing unheated, maintain daytime temps at least 45-55 F and keep night temps above freezing using thermal mass and row covers.
• If heating, keep night temps 55-65 F for vegetables and 60-70 F for herbs; provide 12-16 hours of light for leafy crops, 14-18 hours for fruiting crops.
• Use LED grow lights for efficiency; target 100-250 umol/m2/s PPFD for leafy greens and 300-600 umol/m2/s for fruiting crops (if using PPFD measurements).

Practical winter tips:

• Use double poly or thermal curtains to reduce heat loss at night.
• Group plants with similar temperature and light needs to reduce energy waste.
• Monitor CO2 if heating tightly sealed greenhouses; CO2 enrichment can improve winter growth for fruiting crops but only if ventilation is managed.

Varieties and crop choices: concise lists by season

Spring favorites:

• Lettuce: ‘Romaine’, ‘Buttercrunch’, ‘Oakleaf’.
• Brassicas: ‘Green Magic’ broccoli, ‘Ruby Perfection’ cabbage.
• Herbs: ‘Italian Flat’ parsley, ‘Extra Dwarf’ basil for early starts.

Summer favorites:

• Tomato: indeterminate ‘Cherokee Purple’ or greenhouse varieties like ‘Trust’ or ‘Geronimo’ for disease resistance.
• Cucumber: ‘Marketmore’ or greenhouse parthenocarpic types for no-pollination fruiting.
• Pepper: ‘California Wonder’ or ‘Gypsy’ for reliable greenhouse set.

Fall/winter favorites:

• Kale: ‘Winterbor’, ‘Red Russian’.
• Spinach: ‘Bloomsdale’ for cold tolerance.
• Lettuce: winter mixes and cut-and-come-again varieties.

Choose disease-resistant varieties when available and opt for compact or greenhouse-specific cultivars for small structures.

Year-round greenhouse management checklist (numbered steps)

1. Record your local climate zone, greenhouse dimensions, and whether you have heating and supplemental lighting.
2. Build a calendar: sowing dates, transplant dates, and harvest windows for each crop; stagger sowings for continuous supply.
3. Install basic monitoring: thermometer/hygrometer, soil moisture sensor, and light meter or timer for lights.
4. Implement sanitation: weekly bench cleaning, prompt removal of crop debris, and quarantine for new plants.
5. Set up integrated pest management: sticky traps, beneficial insects, and threshold-based treatment plans.
6. Plan crop rotations and succession plantings to avoid root diseases and nutrient depletion.
7. Keep records of varieties, yields, problems, and environmental settings to refine production each year.

Final practical takeaways

• Match crops to your greenhouse capability: prioritize cold-tolerant greens in unheated structures and reserve energy-intensive fruiting crops for heated, well-lit greenhouses.
• Monitor and control temperature, humidity, and light as the three most important variables. Small investments in measurement and control yield large improvements in crop quality.
• Succession sowing and intercropping maximize space and spread labor and harvests across the year.
• Sanitation and integrated pest management reduce losses more reliably than reactive chemical sprays.
• Use thermal mass, double covers, and row covers to extend seasons without dramatically increasing heating costs.

A well-managed New York greenhouse will provide fresh vegetables and herbs outside the typical outdoor season, increase farm or home productivity, and allow you to experiment with high-value specialty crops. Start with a seasonal plan, measure carefully, and iterate each year to refine what works best for your location and market.