Cold-frame calendar (beginner)

A cold frame is a mini greenhouse: box + clear lid. This calendar is a sequence, not a climate guarantee. Shift weeks by your frost dates.

Build / ready (before you need it)

• Frame sits level on soil or a raised bed; lid slopes to shed rain/snow
• Lid opens and props securely (ventilation days matter more than insulation myths)
• Thermometer inside — you manage heat spikes, not just cold

Late summer → early fall

• Start fall broccoli / kale / spinach so plants are established before hard freeze
• Direct sow radish / lettuce for quick cool harvests
• Mulch paths; clear weeds that will steal winter light

Hardening into the frame

• Move transplants in gradually (shade cloth or cracked lid on hot afternoons)
• Water in the morning; wet foliage overnight invites disease in closed frames
• Watch daytime highs: crack the lid above ~45–50°F (7–10°C) on sunny days

Deep winter

• Harvest outer leaves; do not empty the frame in one greedy weekend
• Brush snow off lids; leave snow against sides as free insulation where safe
• On bitter nights, add an inner row cover — not a space heater fantasy

Late winter → early spring

• Sow earliest peas / spinach / radish weeks ahead of open-garden dates
• Use frame to harden nursery starts before bed transplant
• Remove lid entirely once nights stay above your crop’s comfort (or move frame to next bed)

Do not skip

• Ventilation plan for sunny freezes (closed + sun = cooked greens)
• Pest check under lids (slugs love enclosed damp)
• Backup: row cover in open beds if the frame fills up

More depth: Greenhouse / cold frames angle. Sequence beds with seasonal planting order.

If season extension is one piece of a wider backyard system (water → beds → animals → storage), a structured guide can help after the frame itself is built and venting is habit:

Build the box. Learn to vent. Then stretch the season.