Plant Seeds Now For Fall Harvest

What to Plant

Even though the summer is more than half-way over, it’s still not too late to plant many of your favorite vegetables and herbs. The key is to know what to plant and when to plant it. This guide can help! The trick is you have to choose crops that have shorter (fewer than 70 days) maturing times. Don’t try planting watermelon seeds in August. They take 100+ days to produce fruit. They’ll never make it before the frost comes and kills them. Crops that can be planted in late summer include:

Broccoli Raab
Turnip Greens
Bus Beans
Leaf Lettuce
Swiss Chard

How to Know When to Plant

 In order to figure out when the plant your fall crop seeds, you’ll need to know:
  •  the “days to maturity” of your seeds- This number means how many days until your crops will be ready to harvest and is almost always listed on the seed packet
  • the average first frost date of your area- Here in the Chicago area our first frost occurs around October 15, so you’ll want to make sure your plants will be ready to harvest by this date.
  • the frost tolerance of your crops- If you’re growing crops that can withstand a few light frosts, then you don’t have to worry so much about making sure they will be mature by your first frost date.  To calculate planting time for these plants, add two weeks to your average frost date and use that as your reference point. 

In order to figure out when to plant your seeds all you need to do is take your average frost date and then count backwards from that date using the “days to maturity.”  Here’s an example:

Days to Maturity
Frost Tolerant?
Must Be Harvested By:
Must Be Planted By:
Bush Beans “Contender”
50 days
October 15th
August 21st
Baby Carrots
57 days
November 1st
September 1st

Tips For Starting Your Fall Garden

  • August is the prime time to plant short season annual crops as well as some perennial vegetable crops such as garlic.
  • Most “big box” stores get rid of their seed displays in July.  To find seeds for sale, try local garden centers or order online.
  • Try “succession planting” – Instead of planting all your seeds at the same time, stagger your plantings over a three week period.  This way your plants will mature at different times providing you with a longer harvest.
  • If you want to keep some fresh basil plants inside your house over the winter, now is a good time to start those seeds as well.  Start them in containers so that they are easy to bring indoors.
  • The remaining heat during the later part of the summer can make it hard for cool season crop seeds to germinate.  Seeds need moist soil and some protection from the hot sun for best germination.  After planting the seeds and watering well, keep soil moist and shade plants by lightly covering the soil with a lightweight fabric, window screen, or used plant flat with holes in it.  Check on the seeds and provide more water if needed.  Once seeds have germinated, remove covering. 
  • If you’d like to grow your own garlic, now is the time to plant.  Garlic is grown by planting garlic cloves, not from seed. “Seed garlic cloves” can be purchased on garden centers, or you can plant garlic you buy at the Farmer’s Market.  Just break the head of garlic into individual cloves, then plant each clove 6 inches apart and 4 inches deep, anytime from September on. The garlic will wait in the soil over winter and send up green shoots in the early spring.  Harvest garlic in mid-summer.
  • Similar to garlic, you can also plant a variety of onions known as “walking onions.”  These onions produce their own baby onion “sets” at the top of a long stem.  Once the “set” is large enough it will fall onto the ground, take root, and grow into a new onion plant.  A patch left alone will spread throughout a space, hence why they are called “walking onions.” Like garlic, you plant “walking onions” by planting small clove-like “sets” instead of seeds.  Online retailers start taking orders for these onions in late summer for fall shipping.   “Walking” onions typically produce bunching green onion crops, rather than the large bulbing onions.
  • If you do plant perennial crops, such as garlic or the “walking onions,” be sure to make yourself a note where you planted what.  Most plant markers won’t survive our winters.  In the spring when it’s time to start working your garden, you’ll need to know where those perennial crops are so that you don’t disturb them.  
  • You can even extend your harvest past the first frost date by planting frost tolerant crops (such as kale, spinach, and carrots, to name a few) and by providing frost protection such as “frost fabric” or “cold frames.”

Other Resources:

Fall Vegetable Garden

Planting Garlic

Extending the Vegetable Harvest

Fall Vegetable Garden Video

Johnny's Select Seeds Fall Planting Calendar

Johnny’s Select Seeds Growers Online Resources

Article: A Garden For All Seasons by Eliot Coleman

Cooperative Extension Information Search Engine