High-country gardener’s checklist for September
Vail, CO Colorado
September is a busy month for high-country gardeners. We could experience our first frost any day now. Below is a checklist for gardeners to review as we anticipate the lower temperatures.
Cut back perennials after they turn brown. There are a few exceptions that should not be cut back.
Add fresh mulch to planting beds and around trees. This helps to control weeds, insulate plants, increase organic matter and retain water.
Using fallen leaves as garden mulch is discouraged because the leaves will not decompose in cold winter weather, instead forming a slimy, plant-smothering mat that will be a mess to clean up in the spring.
Divide and relocate overcrowding perennials while plants are still identifiable and weather is cooler.
Continue to deadhead to maximize color as long as the weather is warm.
Cover or move annual planters indoors at night to prolong life and avoid frost-bite or freezer-burn damage.
If a hard-killing frost damages the stems and foliage, clean up and cut back before they start to mildew.
If you like, you can take cuttings from annuals such as geraniums, verbena, coleus, impatiens and begonias. These will usually root within a month and can be grown indoors for mid-winter blooming color.
Aerate lawn to reduce compaction. For best results, thoroughly soak the soil a day or two before you aerate or wait for a good rain day.
Add organic matter such as royal compost to enrich the soil.
Continue pulling weeds by hand until growth diminishes.
To prevent the spread of fungus spores in the spring, rake up and dispose of any aspen leaves that show signs of Black Spot. Do not compost them.
Harvest green tomatoes before the first frost. Wrap them in newspaper, and store in a dry, cool place. To ripen them quickly, place tomatoes in a brown paper bag with some apples.
Bring house plants back indoors when nighttime temperatures start dropping below 55 degrees. Spray them first with an insecticidal soap spray or neem oil, or dust the soil with systemic insecticide granules/diatomaceous earth or Cedar Zone Prill Dry Insect Repellent to avoid bringing insects and other pests indoors.
Plant spring-blooming bulbs when soil cools to below 60 degrees. Bulbs may be easily planted through November, as long as the ground is not frozen.
When selecting bulbs, choose firm, unblemished bulbs.
Trees and shrubs
Plant new trees and shrubs. They are going into dormancy now and will be less susceptible to transplant shock. Adding a mycorrhizal supplement also will minimize plant stress by promoting immediate root development.
Water new plantings as long as the ground remains unfrozen.
Turn down the percentage adjustment on your irrigation clock as temperatures and precipitation drop.
As the temperature decreases, reduce watering and fertilization to allow plants too naturally “harden off” before winter.
Schedule your irrigation blow-out, typically done in early October.
For more detailed seasonal information, become a member of the Wildflower Farm. You’ll receive the members-only monthly newsletter and exclusive discounts.
Wildflower Farm is located in Edwards on U.S. Highway 6. Reach them at 970-926-5504 or firstname.lastname@example.org.