What to plant this week in London, ON
London, ON gardeners are in a brief transition window between the last frost threat of mid-April and your official first harvests starting now; with overnight lows still dipping near -10°F, protect tender crops like Basil and Okra while enjoying early yields from mature Summer Squash and Zucchini.
The next 7 days
London, ONGrowing in London right now
- The clay-loam soils common in Middlesex County retain moisture well but can become crusted after spring rains; loosen the top inch before planting transplants to ensure drainage for roots of Celery and Leeks.
- With first frost historically arriving around October 17, prioritize harvesting late-season crops like Pumpkins and Winter Squash soon rather than waiting for a hard freeze that may rot the fruit.
- Be mindful of high humidity levels typical in Southern Ontario summers which favor fungal issues on Garlic and Potato plants; ensure good air circulation by staking tall varieties like Sunflowers.
- Take advantage of the narrow growing window between the April 21 average last frost and late October to maximize yields from warm-season staples like Watermelon and Honeydew Melon.
Sow this week
No direct sowing windows open this week.
Transplant this week
Nothing is due to go out this week.
Harvest soon
45 crops- Basil
- Borage
- Bush Bean
- Cantaloupe
- Celery
- Cleome (Spider Flower)
- Cosmos
- Cowpea (Black-Eyed Pea)
- Cucumber
- Dahlia
- Edamame
- Fennel
- Flour Corn
- French Marigold
- Garden Verbena
- Garlic
- Ghost Pepper (Bhut Jolokia)
- Gourd (Ornamental/Bottle)
- Honeydew Melon
- Leek
- Lima Bean
- Lisianthus (Prairie Gentian)
- Loofah (Luffa)
- Malabar Spinach
- Nasturtium
- Okra
- Ornamental Sweet Potato Vine
- Parsnip
- Pole Bean
- Potato
- Pumpkin
- Roselle (Cranberry Hibiscus)
- Scarlet Runner Bean
- Shiso (Japanese Basil)
- Summer Savory
- Sunflower
- Sweet Corn
- Sweet Potato
- Thai Basil
- Vinca (Madagascar Periwinkle)
- Watermelon
- Winter Squash
- Yellow Summer Squash
- Zinnia
- Zucchini
Seasonal tips
- Succession sow bush beans and sweet corn every two weeks for continuous harvests through summer.
- Pinch back the tips of basil and okra to encourage bushier growth rather than flowering too early.
- Add a thin layer of straw or shredded leaves around heavy feeders like pumpkins and squash to retain moisture.
Pest & disease watch
- Monitor for Early Season Aphids on newly transplanted Basil, Shiso, and Garden Verbena as aphid populations surge with rising temperatures.
- Watch closely for Squash Vine Borers attacking the stems of Pumpkins, Yellow Summer Squash, and Cucumbers, especially if plants appear wilted during hot afternoons.
- Check for Spider Mites on leafy greens like Malabar Spinach and Fennel, which thrive in the warm, dry spells between London's frequent rain showers.
Watering this week
Provide about 1 to 2 inches of water per week, applying it deeply in the morning to reduce evaporation and disease risk.
Harvest zucchini and summer squash early in the day when they are most tender and flavorful for your table.
London gardening questions
3Is it safe to transplant my Basil and Okra seeds now?
While you can start these indoors earlier, they are listed for harvest soon rather than sowing or transplanting this week; wait until soil warms up further or use row covers to protect them from the residual chill before the April 21 frost date passes.
How long do I have to harvest my Watermelon and Pumpkins?
With an average first frost around October 17, aim to pull your Watermelons and mature Pumpkins within three weeks to prevent cracking from heavy rains or rotting before the ground freezes.
What should I do if my Garlic plants are bolted early due to recent warmth?
Since Garlic is listed for harvest soon this week, check bulbs immediately; if they have developed a central stem and papery skins are forming, dig them up now rather than letting them flower and lose size.
Other cities in zone 6a
12See the full zone 6a guide → · Plan your London garden in SproutGuide →