Polytunnel Prep: Crops to Start and Protect

As autumn cools and outside beds are cleared, your polytunnel becomes the secret to year-round harvests. October is the month to tidy, sow, and shelter—setting up reliable winter salads, early spring greens, and protected tender plants. Here’s how to prep your polytunnel for cooler weather, with top crops to sow and proven ways to keep them thriving through winter.

Why Prep Your Polytunnel in October?

• Extend the growing season: Get fresh food earlier and longer than in outdoor beds.
• Protect tender crops: Shield plants from frost, harsh wind, and heavy rain.
• Use precious space efficiently: Squeeze in extra sowings and overwintering veg while prepping the structure for storms.

Step 1: Clear and Clean

• Remove all spent summer crops, weeds, and old mulch.
• Sweep floors, tidy tools, and compost old plant debris outside the tunnel.
• Wash inside surfaces with horticultural soap to remove algae, dust, and pests.
• Check for holes or tears—repair before winter gales arrive.

Step 2: Refresh Beds & Add Mulch

• Top up soil with homemade compost, worm castings, or rotted manure for new and overwintered crops.
• Rake over and add a light dusting of seaweed meal or slow-release organic fertilizer if needed.

Step 3: What to Sow and Plant Now?

Greens & Salads

• Winter lettuce (e.g., ‘Winter Density’, ‘Arctic King’)
• Spinach, Swiss chard, rocket, land cress, mustards, pak choi
• Oriental greens: mizuna, tatsoi, komatsuna
• Corn salad (mâche) and claytonia (winter purslane)

Alliums

• Spring onions, garlic, shallots

Early Roots

• Fast baby carrots, radish, turnip, beetroot

Herbs

• Parsley, coriander, dill, chervil—these prefer cool, moist air

Step 4: What Needs Protecting?

• Tender herbs or late chillies/peppers: Bring in from outside to extend cropping.
• Young perennials or “forcing” rhubarb/potted strawberries: Store in tunnel for an early start next year.
• Seedlings and plug plants for spring: Set up shelves or benches, prepped for late winter sowings.

Step 5: Polytunnel Care for Winter

• **Ventilate on sunny days—to reduce condensation and fungal risk.
• **Water only when the soil is dry—less frequently than in summer, but don’t let crops wilt.
• Keep fleece or cloches handy: Use inside the tunnel for double protection on frosty nights.
• Monitor for pests: Slugs, snails, and aphids are drawn to cozy winter climate—check trays, pipes, and under pots.

Bonus Tips

• Sow salad trays inside the tunnel for cut-and-come-again greens.
• Keep tools and watering cans inside to prevent freezing.
• Plan your crop rotation for spring—beds sown to autumn greens can flip to tomatoes or beans later.

Wrapping Up

Fall is your polytunnel’s moment to shine: early greens, cold-hardy salads, and a safe home for tender plants. With a day’s prep and the right crops, you’ll harvest fresh, healthy produce all winter and set the stage for maximum spring abundance.