Summer and early fall can be an ideal time to sow seeds, whether it be vegetables, lawns, or cover crops. Extend your vegetable garden longer into the season and enjoy multiple harvests into the fall.
Sowing Cool-season Vegetables in Mid-to-late Summer
Cool-season vegetables can be planted in the earliest spring for summer harvest but can also be planted in summer, for fall harvest. Aim to sow your summer seeds so that plants will start to mature when the weather cools off in the fall.
Cool-season vegetables are able to withstand a light frost. In some cases, such as kale, carrots & Brussel sprouts, the flavor improves after a frost!
Summer and autumn seed sowing is part of the greater topic of planting cool season vs. warm season vegetables in your garden.
Single Seeding / Single Harvest Crops
|Crop||Days to Harvest||Cold Tolerance|
|Beets||50-60 days||High 20s|
|Broccoli||50-70 days||Tolerates light frost|
|Brussel Sprouts||90-100 days||Down to 20°F|
|Cabbage||50-90 days||Down to 20°F|
|Carrots||50-70 days||Down to 15°F|
|Cauliflower||60-80 days||Tolerates light frost|
|Garlic||Harvest following summer||Winter hardy|
|Green Onions||60-70 days||High 20s|
|Kale||40-60 days||Down to 20°F|
|Kohlrabi||50-60 days||Tolerates light frost|
|Leeks||70-80 days||Down to 20°F|
|Lettuce||40-60 days||Down to 20°F|
|Parsley||70-90 days||Down to 20°F|
|Parsnips||100-120 days||Down to 15°F|
|Peas||70-80 days||High 20s|
|Spinach||30-40 days||Tolerates light frost|
|Swiss Chard||40-60 days||Tolerates light frost|
|Turnips||50-60 days||Tolerates light frost|
Multiple Seeding / Multiple Harvest Crops
Fast maturing plants which are not cold tolerant can also be summer-sown to produce multiple crops in a single season. For continuous harvest, sow a fresh crop every 3-4 weeks.
|Crop||Days to Harvest|
|Mustard Greens||30-40 days|
Summer & Fall Lawn Seeding
Mid-August to late September is the ideal time to seed a lawn in Wisconsin.
- Conditions are favorable for germination & growth
- Fewer weed seeds are germinating
- There is ample time for young grass to get established before winter
Dormant seeding can also be done in early to mid-November. The seed will remain dormant through the winter and germinate in spring. This technique is best suited for areas of consistent snow cover.
Cover Crops / Green Manure Crops
A cover crop is essentially a living mulch – a fast-growing crop that is grown on empty soil to prevent soil erosion and keep weeds from growing. Most cover crops produce flowers that are valuable to beneficial insects, although these crops should be cut before they produce seed to avoid self-seeding. Cover crops are also known as Green Manure because they are tilled into the soil, providing organic matter and nutrients.
Cover crops can be sown in early spring to prepare a newly cleared garden area for the first planting. They are also utilized after the summer harvest to replenish the garden for the next season. For this application cover crop seed should be sown 4 to 8 weeks before the average first frost (September 27th in Cedarburg, Wisconsin).
The foliage will be killed by the frost and the dead plant material will provide winter mulch before being tilled into the soil in spring. Legumes are especially valuable as green manure crops because of their ability to capture atmospheric nitrogen and hold it within their own plant tissues. This nitrogen is then returned to the soil, where it can be used by other plants, when the legumes die, decompose, and are tilled into the soil.
Buckwheat (Fagopyrum esculentum)
- Frost sensitive annual
- Days to Maturity: 30-40 days
- Adds phosphorus. Grows very quickly and breaks down quickly in the soil, allowing for planting in the same area just 3 to 4 weeks after incorporating it into the soil.
Crimson Clover (Trifolium incarnatum)
- Frost-tolerant annual
- Days to Maturity: 60-90 days
- Showy red blossoms invite beneficial insects, Fixes nitrogen. Grows well in cool weather.
Fava Bean (Vicia faba ‘Sweet Lorane Improved’)
- Frost-tolerant annual
- Days to Maturity: 30-60 days
- Highest nitrogen-fixing rate. Large, deep roots break up heavy clay & compacted soil. Germinates in soil temperatures as low as 35°F, and plants are fast-growing and very cold hardy.
Peas & Oat Combination (Pisum sativum & Avena sativa)
- Frost-tolerant annuals
- Days to Maturity: 50-70 days
- Pea plants fix nitrogen and flowers attract beneficial insects. Oats provide organic material and suppress weeds. When sown in the fall, peas and oats grow well in the cool weather but are killed by winter weather.