Gardening Guides
Rocky Mountain Gardener's September Checklist
Sharpen your spade and grab your gloves — warm days and cool nights in the garden mean it's planting time
Ahhhh, September! The worst of summer’s intense heat is gone, the glare of the sun has softened and it’s delightful to be active in the garden once again. Warm days and cool nights are ideal for getting new plants established. The soil is warm and workable, allowing for good root growth and development before the winter, and cooler air temperatures lessen the amount of transpiration — and shock — common during the heat of summer.
More ideas for gardening in the Rockies
More ideas for gardening in the Rockies
Plant trees, shrubs and perennials. If you’ve been itching to add some color or structure to your landscape, now is a great time to shop for plants. Nurseries will be pushing sales with special promotions and discounts so they can clear out their stock before winter, and you, the consumer, win.
Plant for winter color. Broadleaf evergreens should be a priority for your fall planting schedule. These plants bring much-needed color and texture to the winter landscape but can suffer from our region’s low humidity, intense sunlight and drying winds.
September planting allows roots to develop, especially important for evergreens during the winter, because the roots’ ability to absorb water helps offset the plant’s moisture loss via its persistent foliage. In general, broadleaf evergreens look their best when planted in a protected location with filtered shade or morning sun and afternoon shade.
The most drought-tolerant options for this region include Oregon grape holly (Mahonia spp), manzanita (Arctostaphylos spp) and yucca (Yucca spp) — all hardy to about 7,500 feet in elevation. Selections of these plants are native to many locations across the Rockies.
September planting allows roots to develop, especially important for evergreens during the winter, because the roots’ ability to absorb water helps offset the plant’s moisture loss via its persistent foliage. In general, broadleaf evergreens look their best when planted in a protected location with filtered shade or morning sun and afternoon shade.
The most drought-tolerant options for this region include Oregon grape holly (Mahonia spp), manzanita (Arctostaphylos spp) and yucca (Yucca spp) — all hardy to about 7,500 feet in elevation. Selections of these plants are native to many locations across the Rockies.
Firethorn (Pyracantha spp) needs just a bit more water, as do boxwood (Buxus spp) and most of the evergreen Euonymus species. All of these plants are best at elevations of 6,000 feet or below.
Application of an antidesiccant to the foliage in late November may help foliage hold its color better throughout the winter. Mulching and winter watering are critical to keep plants hydrated.
Application of an antidesiccant to the foliage in late November may help foliage hold its color better throughout the winter. Mulching and winter watering are critical to keep plants hydrated.
Plant for permanence. Trees are a big investment of time and money but are often crucial to creating the architectural aspects of a landscape: providing shade or privacy, modifying wind or noise, framing a view, etc.
Fall planting can make purchasing a tree easier on your budget, and it’s less stressful on the plant, as well. Confer with a nursery or a landscape professional to select a healthy tree that will adapt well to the growing conditions indigenous to your site.
For example, what is your hardiness zone or microclimate? Soil type? Water budget? Available space? Trying to change your environment to match the needs of a plant is rarely successful in the long run, so it’s best to be an informed gardener-buyer.
Fall planting can make purchasing a tree easier on your budget, and it’s less stressful on the plant, as well. Confer with a nursery or a landscape professional to select a healthy tree that will adapt well to the growing conditions indigenous to your site.
For example, what is your hardiness zone or microclimate? Soil type? Water budget? Available space? Trying to change your environment to match the needs of a plant is rarely successful in the long run, so it’s best to be an informed gardener-buyer.
Transplant perennials. A good rule of thumb to remember is that perennials that flower in the spring and early summer should be moved in the fall, and those that flower in the late summer and fall should be moved in the spring. The idea is to let the plants “settle in” to their new location (get some root growth) before the push to flower occurs.
Although this is not a hard and fast rule, peonies (Paeonia spp) in particular must be moved in the fall. When transplanting peonies it’s important to site them in full sun and provide them with a deep, loamy, well-draining soil. Set the root buds (or “eyes”) 1 to 1 1/2 inches below the soil level. Peonies that are planted too deeply will not flower.
Other good candidates for moving now include poppies (Papaver spp), phlox (Phlox ssp) and daylilies (Hemerocallis spp). Mulch should be used to protect fall transplants by keeping soil temperatures above freezing longer into the fall (permitting better root growth).
Although this is not a hard and fast rule, peonies (Paeonia spp) in particular must be moved in the fall. When transplanting peonies it’s important to site them in full sun and provide them with a deep, loamy, well-draining soil. Set the root buds (or “eyes”) 1 to 1 1/2 inches below the soil level. Peonies that are planted too deeply will not flower.
Other good candidates for moving now include poppies (Papaver spp), phlox (Phlox ssp) and daylilies (Hemerocallis spp). Mulch should be used to protect fall transplants by keeping soil temperatures above freezing longer into the fall (permitting better root growth).
Buy spring-flowering bulbs. Tulips, daffodils, hyacinth and more are all available for purchase now. Shop your local independent garden center for large, premium bulbs. Although they may be more expensive, bigger bulbs are usually better — they pack bigger flower buds and more nutrients for growing power.
Buy early while the selection is best, but wait to plant your bulbs until October, when the ground is cooler yet still warm enough for the bulbs to root out and hydrate. (Bulbs planted in overly warm soil may abort their flower buds.) Meanwhile, store your bulbs in a cool, dark place, like a basement closet. Once they're planted, keep bulbs moist throughout the winter, watering monthly if necessary.
Buy early while the selection is best, but wait to plant your bulbs until October, when the ground is cooler yet still warm enough for the bulbs to root out and hydrate. (Bulbs planted in overly warm soil may abort their flower buds.) Meanwhile, store your bulbs in a cool, dark place, like a basement closet. Once they're planted, keep bulbs moist throughout the winter, watering monthly if necessary.
Adjust your irrigation clock. Lawns need less water as summer winds down. Although soil conditions, sun exposure and turf types must be taken into account, your lawn will need only about half as much water in September as it did in July.
GardenQuilt Cover
Be prepared for frost. September brings the first frost — or snow! — to many Rocky Mountain gardens, and no one wants to see a great crop of basil or a beautiful container garden turned into mush overnight.
Keep white sheets or commercial frost blankets handy; lightweight, breathable and reusable throws are just the thing to have on hand to drape over your annual flowers and tender vegetables when frost threatens. The light color lets sunlight in for photosynthesis and also traps solar warmth for continued plant and fruit growth. Multiple layers provide even greater insulation.
More: Guides for your Rocky Mountains garden
Keep white sheets or commercial frost blankets handy; lightweight, breathable and reusable throws are just the thing to have on hand to drape over your annual flowers and tender vegetables when frost threatens. The light color lets sunlight in for photosynthesis and also traps solar warmth for continued plant and fruit growth. Multiple layers provide even greater insulation.
More: Guides for your Rocky Mountains garden