Prep your garden now before the first freeze
This is the time of year that gardeners are literally counting the days until the first frost hits. Many of us are hoping it will be later, so those last tomatoes can ripen on the vine and we can get our yards ready for fall.
According to the Yellowstone County Extension Office, our average first frost date is September 22, but keep an eye on the weather forecast -- a frost that will kill tender plants occurs at 26-30 degrees.
If you have vegetables that are still ripening or annuals that you are still enjoying, be prepared to cover them at night, keeping the covers from touching the leaves. Be sure to remove the covers by mid-morning, or else your plants may get too hot as the temperature rises during the day. Give your flowerbeds and pots a fall makeover by planting hardy mums, kale and pansies. These plants can all withstand cooler temperatures.
If Jack Frost sneaks up on you and leaves frost on your garden, spray with water before the sun hits the plants. If the frost was light, this may save your plants by thawing them slowly. If your vegetables froze, don't rush to pick them -- let the soil and plants warm before harvesting them. If we had a hard freeze, allow the ground to thaw before harvesting root crops.
Frost isn't necessarily a bad thing. Several fruits, such as apples, chokecherries and plums will continue to ripen and become sweeter after a frost. Potatoes and onions will store better after a frost kills the tops. Pumpkins and winter squash should be harvested after a light frost, but before a heavy freeze.
Keep watering (as needed), mowing and raking your lawn until winter arrives. Long, matted grass and leaves left over the winter may cause problems next spring. Stop watering your established trees and shrubs when they start to go dormant (leaves turn color and drop). Watering, fertilizing with high nitrogen fertilizers and pruning live wood can encourage a new flush of growth which will make your trees and shrubs vulnerable during winter. But, if we have a warm and dry fall (not so far), we may need to apply more water. Continue to water newly planted trees and shrubs as usual.
To protect tender, dark-barked trees from sun scorch, wrap the trunks with tree wrap. If you had problems with insects or disease on deciduous trees or shrubs, fall is also a good time to apply dormant oil/lime sulphur spray. Wait until the plant is completely dormant to apply. Watch your night temperatures -- dormant oil can't be applied if we are expected to freeze.
Remember to think about spring, while you're out there working in your yard this fall. This is the time to plant spring blooming bulbs -- tulips, daffodils, crocus, hyacinth, etc. Also, fall is a great time to plant perennials, trees and shrubs. Plants experience much less transplant shock when they are planted in the fall. The shorter days and cooler nights create less need for water.
There are no hard and fast rules for gardening in September, but keeping these things in mind and an eye on the weather forecast will set you up for a good start next spring.