What to plant this week in Ann Arbor, MI
Ann Arbor gardeners are racing against the clock, as last frost doesn't arrive until April 21st and winter squashes are just beginning to mature. This week marks the critical harvest window for heat-loving crops like watermelons and zucchini before the Michigan chill sets in. With nights dropping toward -10°F this month, protect your late-blooming dahlias from snapping back into dormancy.
The next 7 days
Ann Arbor, MIGrowing in Ann Arbor right now
- Ann Arbor's clay-heavy loam drains slowly; add generous amounts of compost or coarse sand to your planting beds now for winter squash roots that need aeration.
- With the frost date at April 21st, any transplants not hardened off by mid-October risk losing yield; focus your final harvest efforts on zucchini and yellow summer squash this week.
- The city's urban heat island effect allows basil and Thai basil to keep producing into late October if you provide a cold frame or row cover after sunset.
- Local rainfall can be erratic in autumn, so check drainage around perennial beds like borage and cleome to prevent rot before the ground freezes.
Sow this week
No direct sowing windows open this week.
Transplant this week
Nothing is due to go out this week.
Harvest soon
41 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
- Lima Bean
- Lisianthus (Prairie Gentian)
- Loofah (Luffa)
- Malabar Spinach
- Nasturtium
- Okra
- Pole Bean
- 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 tops of zucchini and squash plants now to encourage more fruit development rather than just vines.
- Cut back dying foliage on basil and borage after heavy harvesting to promote a second, smaller flush of growth.
Pest & disease watch
- Late-season aphids are clustering on the new growth of cosmos and zinnias as temperatures moderate; use a strong water spray or neem oil if populations spike.
- Spider mites become active in Ann Arbor's dry autumn winds, targeting the leaves of sunflowers and edamame plants under stress from drought.
- Slugs and snails remain very active near the wet basements of older Ann Arbor homes, feeding heavily on young pumpkin vines and nasturtium foliage.
Watering this week
Water deeply in the early morning to reduce evaporation while supporting heavy fruit production on melons and squash.
Pull any volunteer weeds immediately around your transplants like edamame and fennel before they compete for nutrients.
Ann Arbor gardening questions
3Can I still transplant cool-season crops like garlic into my Ann Arbor garden this week?
No, garlic must be planted in late summer or early fall before soil temperatures drop below 50°F to establish roots before the frost. Since your average last frost is April 21st, you should wait until mid-to-late August for optimal garlic planting success.
How do I extend the harvest of my watermelon and cantaloupe past this week's first frost?
Cover individual vines with clear plastic tunnels or floating row covers immediately to trap heat, but be aware that Ann Arbor's hard freeze occurs around October 17th. If a killing frost hits before maturity, cut the fruit from the vine and ripen it indoors on newspaper.
Are there specific pests I should watch for in my zucchini plants right now?
Watch closely for squash bugs and cucumber beetles, which can cause rapid wilting as days shorten. Hand-pick any adults found on leaves this week and apply a row cover over the plant to prevent further egg-laying before temperatures drop.
Other cities in zone 6a
12See the full zone 6a guide → · Plan your Ann Arbor garden in SproutGuide →