What to plant in January in USDA zone 5

Sow indoors in January — zone 5

Start these seeds under lights or in a heated propagator so transplants are ready when the outdoor planting window opens.

• Onions and leeks — Late January under lights — they want a 10-12 week head start.

Maintenance in January — zone 5

• Cold frames — Vent on sunny days to prevent over-heating overwintered greens.

Prep and planning — zone 5

• Seed orders — Order tomato, pepper, and brassica seed before mid-month rush.
• Dormant pruning

Universal January tasks

These apply across most US and UK gardens in January, regardless of zone.

• Order seeds for the spring garden — popular varieties sell out by February.
• Sketch a garden plan and rotate crop families away from where they grew last year.
• Clean, sharpen, and oil pruners, loppers, and shovels before spring.
• Inspect overwintered garlic, perennial herbs, and mulch — top up where exposed.
• Set up seed-starting lights and check that timers and heat mats still work.
• Prune dormant fruit trees and grapes on a mild, dry day.

Why this works for zone 5

Zone 5 has average annual minimum temperatures of -20 to -10°F (-29 to -23°C) and a frost-free window from late April / early May to late September / early October — about 150 growing days. Classic Midwest growing zone. Most US gardening books default to zone 5 timing. Mulch garlic and perennials before deep winter freezes.

Dates are zone-wide averages. Local microclimates (south-facing slopes, urban heat, lakeside warmth, elevation) can shift the window by 1-2 weeks within the same zone.

UK gardeners — January

Across the UK, January is the planning month. Sow onions, leeks, and broad beans under cover from late January in milder southern gardens. RHS H4-H5 zones should keep overwintered kale, leeks, and parsnips harvested and mulched.

Source and methodology

Frost-date averages from NOAA Climate Data Online within USDA zone 5. Hardiness boundaries from the USDA Plant Hardiness Zone Map (2023). Crop timing curated against US Cooperative Extension Service publications (UNL, UMN, NC State, Texas A&M, UF/IFAS, Oregon State) and cross-referenced against the RHS sowing calendar. Curated by the Growli editorial team.

Keep going

• ← December in zone 5
• February in zone 5 →
• All zones — what to plant in January
• USDA Zone 5 — frost dates and crop list
• Full 12-month planting calendar

Other zones — January

• What to plant in January in zone 3
• What to plant in January in zone 4
• What to plant in January in zone 6
• What to plant in January in zone 7
• What to plant in January in zone 8
• What to plant in January in zone 9
• What to plant in January in zone 10