What to plant this week in Whitehorse, YT
Whitehorse gardeners face a critical window this week as the last frost risk lingers until May 15, meaning outdoor planting must wait despite late spring warmth. While you can finally start your fall garlic indoors or out, focus primarily on harvesting your maturing summer crops before the September 15 hard freeze arrives.
The next 7 days
Whitehorse, YTGrowing in Whitehorse right now
- Protect all summer squash, zucchini, and tomatoes with row covers tonight if a dip below -4°F is forecasted before May 15.
- Begin planting spring onions or leeks immediately in moist soil to establish roots for the short growing season ahead.
- Harvest your bush beans and pole beans now while they are tender; letting them harden off reduces yield as nights cool rapidly.
- Mulch heavily around young potatoes and rutabagas to retain heat against the intense continental freeze typical of this Yukon valley.
Sow this week
1 crops- Garlic
Transplant this week
Nothing is due to go out this week.
Harvest soon
29 crops- Beefsteak Tomato
- Borage
- Brussels Sprouts
- Bush Bean
- Carrot
- Cleome (Spider Flower)
- Cosmos
- Dahlia
- French Marigold
- Garden Geranium (Zonal)
- Garden Verbena
- Garlic
- Lantana
- Leek
- Ornamental Sweet Potato Vine
- Parsnip
- Petunia
- Pole Bean
- Potato
- Rutabaga
- Scarlet Runner Bean
- Shiso (Japanese Basil)
- Summer Savory
- Sunflower
- Vinca (Madagascar Periwinkle)
- Winter Squash
- Yellow Summer Squash
- Zinnia
- Zucchini
Seasonal tips
- Finish succession planting cool-season greens like lettuce or spinach to maximize the short growing window before frost.
- Apply a thick layer of mulch around winter squash and rutabagas to protect roots from dropping temperatures.
- Prune back any leggy borage or cosmos stems to encourage fresh growth for late summer flowers.
Pest & disease watch
- Monitor aphids on Shiso and Cleome spider flowers, which thrive in Whitehorse's warm microclimates but attract soft-bodied bugs.
- Check for carrot rust flies near your harvested carrots and parsnips before pulling them from the ground.
- Watch for late-season blight on Beefsteak tomatoes as humidity rises with the approaching summer storm front.
Watering this week
Water deeply in the morning to reduce evaporation, but avoid wetting foliage to prevent fungal diseases on tomatoes and squash.
Harvest zucchini and summer squash frequently when they are young to encourage the plant to keep producing fruit throughout the season.
Whitehorse gardening questions
3Can I transplant my dahlia tubers now in Whitehorse?
No, do not move dahlia tubers until after May 15; planting them earlier risks killing the crowns before they can establish roots against the cold ground.
When should I harvest my winter squash and zucchini this week?
Pick your Winter Squash and Zucchini immediately while the fruit is still glossy, as a single frost will ruin their storage potential for the long Yukon winter.
Is it too late to sow beans outside in Whitehorse?
You should wait until after May 15 to sow Bush Beans or Pole Beans directly; starting them indoors now allows you an extra week before the soil warms enough.
Other cities in zone 3a
1See the full zone 3a guide → · Plan your Whitehorse garden in SproutGuide →