Now
14°C · Drizzle
Today
16° / 9°
Soil 6 cm
12°C
First frost
~15 days (Sep 23)
Gardening in Whitehorse
AI field guide · refreshed weeklyWhitehorse Gardening: September 8–14 — Final Harvest & Season Close
You're in zone 4a with 15 days until the average first frost (September 23). Soil at 12°C is still workable but cooling fast; frost can arrive any night now. This is your final push to harvest tender crops and protect perennials before hard freeze. You've had 101 frost-free days since May 30—use them wisely.
Sow outdoors now
Winter rye or hairy vetch
Sow cover crops immediately to prevent erosion and fix nitrogen over winter. Broadcast seed, rake in lightly, and water if rain doesn't come by September 10.
Garlic cloves
Plant now through mid-September for spring emergence. Set cloves 5 cm (2 in) deep, 15 cm (6 in) apart, in well-draining soil amended with compost. Mulch heavily after soil freezes.
Spring bulbs (tulips, crocuses, alliums)
Get them in before soil freezes solid, ideally by mid-September. Chill-requiring bulbs need 12–16 weeks of cold; Whitehorse's winter provides that naturally.
Start indoors now
Microgreens (radish, mustard, broccoli)
Start in trays indoors for winter windowsill harvests. They're ready in 10–14 days and tolerate low light better than full-size plants.
Harvest now
Tomatoes, peppers, eggplant
Pick all fruit now—even green tomatoes ripen indoors in a paper bag at room temperature. Frost will kill plants within days.
Root crops (carrots, beets, turnips, parsnips)
Harvest before hard frost or mulch heavily in place for storage. Soil at 12°C is still soft enough to dig; wait much longer and ground hardens.
Leafy greens (kale, spinach, lettuce)
Cut outer leaves or harvest whole plants. Light frosts improve flavor; hard freeze (below −2°C) kills them.
Herbs (basil, cilantro, dill)
Basil is done at first frost; cut and dry or freeze cilantro and dill now. Perennial herbs (thyme, sage, chives) will regrow from roots.
Tasks this week
- Drain and store garden hoses; shut off outdoor water before freeze.
- Cut back perennials (coneflower, rudbeckia) to 5–8 cm (2–3 in) or leave standing for winter interest and wildlife shelter.
- Mulch tender perennials (roses, lavender) with 10–15 cm (4–6 in) of compost or leaves after soil surface freezes.
- Clean and oil tools; store in a dry place before winter.
- Empty pots and store indoors; frost will crack ceramic and terracotta.
Watch out for
- Frost can arrive any night now—keep frost cloth or row cover handy for surprise cold snaps.
- Wet soil freezes harder and faster; let beds dry slightly before the hard freeze to reduce compaction damage.
- Slugs and aphids are still active in cool, damp weather; remove by hand or spray with insecticidal soap if needed.
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