Prepare for winter is the watchword in October. In the garden world "winter" is signaled by the first killing frost.
With the aid of Master Gardeners on the CSU Extension Help Desk, I verified that the average date of the first killing frost in Colorado Springs is Sept. 21 to 30 (plantmaps.com/interactive-colorado-first-frost-date-map.php). Since that hasn't happened yet, the best information I can give you is watch the weather and expect a killing frost any day now.
A light freeze of 29 to 32 degrees Fahrenheit will kill very tender plants. To extend the season you can cover the most tender plants at night with a sheet or other lightweight protective covering. Be sure to remove the covering first thing in the morning. You may even successfully protect plants with a moderate freeze of 25 to 28 degrees.
If your containers are moveable, they can be put in a protected spot like a garage and then moved back to the garden when the weather warms up.
The first hard frost - 24 degrees and colder - signals the end of the growing season. Most herbaceous perennials will not be able to tolerate weather that cold.
Here's your garden to-do list:
- Early October, stop deadheading roses and reduce water to encourage them to go into dormancy.
- Prune dead, broken or diseased branches from trees and shrubs throughout the month.
- Before a hard freeze, pick and ripen green tomatoes indoors.
- Save seeds of your favorite annuals, but don't expect an exact replication of your current plant. Zinnia seeds saved from a dwarf plant with ivory flowers produced a wide variety of zinnias from the tall California giants to pom-pom zinnias. All saved seeds should be stored in a cool, dry location.
- Flowers like snapdragons, marigolds, violas, moss rose (portulaca), and cosmos are excellent re-seeders. Do not cultivate the soil around these plants if you want more of them next season.
- Pick pumpkins and winter squash by mid-October.
- Fertilize the lawn mid-to-late October. This is considered the most important fertilization of the year by many experts.
- Core aeration in October will benefit lawns that have thatch build up or show signs of soil compaction.
- Plant garlic for harvesting next summer.
- Cover asparagus and rhubarb beds with 3 to 4 inches of mulch.
- Dig up and store tender bulbs such as cannas, dahlias and gladiolus in a dry location.
- Parsley can be dug, divided and potted to grow in a sunny window indoors all winter.
- After fall harvest, heritage raspberry stalks can be cut back to the ground.
- Clean, sharpen and oil tools and equipment before storing them for winter.
- Drain or blow out your irrigation system. Then, using a hose, keep watering according to your water restriction days until the ground freezes.
Get answers to your horticulture questions by calling a Master Gardener Volunteer at 520-7684 or emailing CSUmg2@elpasoco.com. Volunteers will be available on Mondays and Wednesdays from 9 a.m. to noon.