Planning tool

Frost Protection and Season Extension Planner

Use first and last frost dates, catalog crop timing, soil temperature, crop tolerance, row covers, cold frames, hot caps, and removal timing before pushing a garden earlier or later.

Inputs

Last and first frost dates
Use the last expected spring frost and first expected fall frost as planning anchors; hardiness zones do not replace local frost dates.
Catalog crop tolerance
Separate frost-sensitive warm-season crops from cool-season greens and fall-window entries before choosing a cover or planting date.
Cover type and ventilation
Compare lightweight, medium, and heavy row covers with hot caps, cold frames, low tunnels, and water-filled walls, then plan daily ventilation when heat builds.
Pollination and removal timing
Remove covers from cucumbers, squash, melons, pumpkins, strawberries, and similar fruiting crops when bloom and pollinator access matter.

What it returns

Planning guidance

Soil temperature boundary
Season extension does not erase soil temperature needs; use soil warmth with frost dates before direct sowing or transplanting heat-loving crops.
Warm transplant push
UMN says water-filled walls can let tomatoes, peppers and eggplant go out three weeks earlier than normal, but remove them once plants emerge from the top.
Row cover setup
Use row covers with enough slack for growth and anchor all sides; supported low tunnels reduce wind whipping and help keep covers off tender leaves.
Cold boundary
UMN heavy row covers can protect around 20F but block 40 to 50 percent of sunlight and can overheat plants, so use them briefly around freezes.
Light cover boundary
Clemson says lightweight hooped row covers can protect to 28F, while heavier covers are needed for deeper cold snaps.
Ventilation and heat stress
Open tunnels or cloches for ventilation on warm sunny days; UMD warns temperatures under row covers can rise 5-15F and cause heat stress.
Pollination removal
For cucumbers, squash, melons and pumpkins, remove the cover once the plants start to bloom so bees can reach the flowers.
Cool-season greens
Medium row cover in September can keep cool-season greens alive later into fall, while UMD lists lettuce, spinach, arugula and radish as cover candidates from planting through harvest.
Cold frames
Use cold frames for winter greens, smaller herbs, or protected root crops, but ventilate on sunny days and keep soil moist, not soggy.
Catalog boundary
Candidate lists come from catalog season, direct-sow, transplant, and fall-window fields; the extension sources explain how covers and frost dates change risk.

Regional frost-risk fallback

Frost-sensitive warm-season candidates

Cool-season cover candidates

Fall extension candidates

Supporting planning paths

Source basis