The city gardener

Wrapping up the growing season


Although it still feels summery outside, our first frost is right around the corner. But fear not – there’s still plenty to do in the garden! I know I will be soaking up these last weeks of summer by spending as much time as I can outside. Read on for some tips and tricks that will help you make the most of your gardening season and set yourself up for spring success.
First, you can still plant a few veggies for fall harvest. Based on historical Minneapolis weather data, there is a 50% chance that we will see freezing temperatures by mid-October. That’s not much time, but certain vegetables grow quickly and actually prefer cooler fall weather. For example, radishes and spinach planted now will likely reach maturity before the weather gets too cold. Kale is also very tolerant of cold weather and can survive temperatures down to 20 degrees Fahrenheit. Look for seeds with a low “days to maturity” number – ideally, 35 or less. This is the number of days from seed germination to harvest. “Mini” varieties are a good choice for a quick fall crop.
Also, start thinking about planting fall bulbs. Garlic is planted in the fall and harvested the following summer. Hardneck varieties such as Rocambole, Purple Stripe, and Porcelain are winter hardy and ideal for a northern climate. Look for these varieties at local garden centers. Grocery store garlic cloves are usually softneck varieties and won’t grow well in Minnesota.
Other hardy bulbs, such as tulips, daffodils, iris, crocus, allium, and lilies, should also be planted in the fall. These require a cold period to break their dormancy and begin flowering in the spring. Make sure to plant bulbs at the correct depth according to the package directions. If bulbs are planted too deeply, they may not flower well in the spring or may not emerge at all. If too shallow, they may freeze or squirrels or chipmunks may dig them up. Water bulbs until the soil freezes to help prevent them from drying out over the winter.
This is also a good time to divide spring and summer blooming perennials, such as peonies, poppies, and irises. If your plants look overcrowded or are becoming too large for their space, it may be time to divide them! Simply dig up the plant, separate it into smaller pieces using a clean shovel or blade, and replant, leaving space in between each new plant. This helps reduce competition for nutrients and water and improves airflow, keeping plant diseases at bay. If you divide perennials this fall, plan to have them back in the ground four to six weeks before the ground freezes to give time for roots to become established.
Finally, as the growing season comes to a close, it is common to see plant diseases crop up in the garden, especially on tomatoes. Early blight is very common in Minnesota and spreads via spores present in the soil. It develops when temperatures are moderate and humidity is high – conditions that often develop during late summer rains. You may see the lower leaves of your tomato plants turning yellow or brown, and tomato fruits developing leathery black spots. When you clean up your garden in the fall, remove infected plants and dispose of them by placing in a hot compost pile or sending to a municipal yard waste facility. This reduces the likelihood of the pathogen surviving in your soil to the following year. Next year, plan to rotate your tomatoes and plant them in a different spot, where the pathogen is hopefully not present. When planning next year’s garden, you can look for tomato cultivars that are resistant to early blight and other common diseases.
For more information, check out the University of Minnesota Extension Yard and Garden website. Extension resources are written by experts and contain the latest and most reliable research-based information. Happy gardening!


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