Editors note: Get Growing, written by the La Plata County Extension Offices Master Gardener Program, appears every other week during the growing season. It features timely tips and suggestions for your garden and landscape.
By Michelle Flemmings
Fall is the best time to take steps to assure you will have an even better and healthier garden next year. By following a few simple guidelines and starting the process about four to six weeks before the first frost (usually Sept. 11-20 for La Plata County), next spring your garden will be gorgeous.
First, remove all spent heads and foliage from your perennials. This will decrease the chances of diseases and pests overwintering in your garden beds. That being said, I often leave seed head on the echinacea, rudbeckia, helianthus and euphorbia to serve as food for migrating birds.
Fall is a great time to add organic matter to your beds using compost or composted manure. Mix and turn the organic matter into the soil thoroughly. If you choose to use a root tiller, avoid overtilling as this leads to compaction and an unhealthy soil. Do not disturb the perennial beds because this can damage the root systems and lead to unhealthy plants next spring.
Divide any overgrown perennials. Good candidates include lilies, hosta, yarrow, echinacea, Siberian and Japanese irises and ornamental grasses. Do not forget that you can still plant new perennial specimens throughout fall. There is no need to fertilize any of these plantings because this will promote above-ground growth, but not the root growth that is vital to their over-winter survival.
After the first two hard frosts, mulch your garden beds. Apply 2-3 inches if using wood chip mulch, or 4 to 6 inches if using hay, straw or evergreen needles.
Mulching after frost ensures that the soil and roots stay cool. The mulch insulates the soil and helps to maintain a more constant root temperature which decreases the risk of destructive freeze, thaw and soil heaving. After the first freeze, cut perennial stems to 2 inches above ground level. Do not cut the basal (lower) growth that is characteristic of plants such as poppies, hardy geranium, Shasta daisies and penstemon.
Lastly, fall is the time to clean, sharpen and oil your garden tools before storing them for next spring.
Michelle Flemmings has been a Colorado Master Gardener since 2011. She lives in La Plata County.