Fall Gardening Tips

September 22, 2009 at 10:21 pm Leave a comment

Picture4The onset of hard morning frosts and the fading of brilliant autumn leaves in the Gunnison Valley may diminish a gardener’s enthusiasm for the final tasks of the growing season.  The excitement we felt at witnessing the first blooming flowers of spring and participating in the fullness of the summer garden may be giving way to a desire to begin indoor pursuits.  However, putting on your hat and gloves and getting out into the crisp fall air to finish up the season’s work will reap benefits when winter’s cold diminishes and spring emerges once again.  The following are some ideas and jobs to consider as winter approaches…

In General:

  • Plants need less water when going into the dormant season.  Excess water in the fall stimulates new growth which will not be hardened off properly for the winter and will be more susceptible to winter kill.  Soak your plants deeply when you do water, but don’t water as often.  Give all turf, trees and perennial beds a deep watering before the ground freezes.   Use a soil probe or trowel to dig down into the soil in order determine plants’ water needs.
  • Fall is a great time to build a compost bin if you don’t already have one.  Simple compost bins can be constructed very inexpensively.  Add leaves and non-diseased plant material (except weeds that have gone to seed) removed from flower beds to your compost pile.   In addition to creating a wonderful organic top dressing for your flower beds, the composting process kills many of the fungi and insects that might otherwise over-winter on plant material. 
  • Interesting dried seed heads, flowers and stems cut from perennial beds can be used to make beautiful outdoor arrangements.  Collect pine cones, dried seed heads and other things used to make holiday ornaments before they’re covered by snow.
  • Late fall planting is not recommended in the Gunnison Valley – plants don’t have enough time to get established before the ground freezes.  It’s best to plant trees, shrubs and perennials in late spring or early summer and bulbs in the late summer or early fall
  • If you haven’t had a soil test performed on your property, consider doing it this fall.  The results will help to determine the best course of action for fertilizing as you begin to plan for next season.  Do-it-yourself soil test  kits can be purchased at garden centers, or the Extension Office can send soil samples to a lab for testing.
  • Prepare your irrigation system for winter (including hoses!) by expelling all water from the system.
  • This winter, plan to avoid using de-icing salts near lawns, vegetable gardens and flower beds.  Salts can accumulate and damage plant roots.  Consider using sand or sawdust.  If using de-icing salts is necessary, magnesium chloride-based products tend to be less harmful to plants than other de-icing salts.
  • As temperatures drop, be sure to remove any garden chemicals that might freeze from sheds and move them to areas where their storage temperature will not fall below 40F.  Frozen liquids could expand enough to break containers, and may spread concentrated chemicals within reach of children or pets.
  • Fall is a great time to do a thorough weeding in your garden to prevent annual weeds from going to seed and perennial weeds from over-wintering.
  • Clean and oil garden tools before putting them away for the winter


  • Fall is a great time to core aerate the lawn.  It will relieve compaction, allow more  oxygen to reach the root zone of the lawn, help reduce fungal problems and improve the overall health of turf.  Consider using an organic top dressing (such as Gunnison Gold compost) on the lawn after aerating, working it into the holes created by aerating.
  • Fall is a good time to renovate and re-seed the lawn.  Eliminate weeds, amend the soil and plant grass seed in areas that need renovation.  Water seeded areas thoroughly after planting and keep moist as long as the ground isn’t frozen.
  • Rake leaves from lawn areas.  Leaves left on lawn will mat and prevent oxygen and moisture from reaching grass.  Use leaves as brown material on your compost pile.
  • Turf areas should receive a late season fertilization with a quick release nitrogen fertilizer, such as ammonium sulfate.  Even though top growth has slowed, the roots of cool season turf grasses are still quite active in   Autumn.  Fall fertilization will help lawns green up more quickly next spring without the rapid flush of new growth that often happens after early season fertilization.  Soils in our area naturally tend to have high levels of phosphorous and potassium, so addition of fertilizers with these elements is often not necessary.

Picture1 Flower Beds:

  • Herbaceous perennials can be cut back, given a deep   watering and covered with 2-3” of bark mulch or pine needles for winter protection.  Gunnison Gold compost would also be a great  winter topdressing for perennial beds.  Mulch will help the soil to retain moisture and  maintain a more even soil temperature during freeze-thaw cycles.
  • Leaving (non-diseased or insect-infested) dried plant material in flower beds can be good for winter interest and protection.  Remaining dried foliage and stems acts as a sort of “snow fence” by capturing and storing snow that will keep the ground moist during  periods of snow melt. 
  • Work screened compost gently into the soil in flower beds, if possible to a depth of at least 2”.  Be careful not to damage the roots of perennials.
  • In a cold climate like ours, late fall is too late to divide perennials.  Plants should be given enough time to get established before the ground freezes after dividing.  Wait until spring when plants begin active growth or late summer as growth slows to divide perennials.
  • If planting bulbs in the late fall, plant a bit more deeply than usually recommended to give bulbs more time to get established before the ground freezes to the depth at which they’re planted.
  • Fall is a good time to plant wildflower seeds.  Seeds planted in the fall will undergo the necessary stratification during cold winter temperatures and will emerge from dormancy as melting spring snow gives way to warmer temperatures.
  • Collect seeds from your garden to store for next year or to share with friends.  Dry seeds thoroughly and store them in breathable envelopes in your refrigerator.

 Picture2Trees & Shrubs:

  • Consider using rose collars around the base of non-native rose bushes.  Collars can be filled with 8-10” of mulch to protect the roots of the plant and maintain soil moisture and a more even soil temperature during freeze & thaw cycles
  • Aspen trees (and other smooth & thin barked trees in our area, such as ash and maple) are extremely prone to frost cracking in the spring and fall as freezing nighttime temperatures and warm daytime temperatures cause  expansion and contraction of tissues, especially on the south and west sides of trunks.  Consider wrapping the trunks of younger thin & smooth barked trees with tree wrap to protect them from frost cracking and sunscald.  Tree wrap should be removed in the late spring.
  • Avoid pruning woody plants until next growing season if possible.  Internal tissues exposed by pruning cuts may be damaged by low temperatures.  If it is necessary to prune broken branches during the fall or winter, leave a stub a few inches long, which can be pruned back to the branch collar in the spring.
  • Consider staking newly planted trees that might be susceptible to damage from wind and snow loads this winter.  Be sure to use staking material that will not damage the bark of trees by rubbing during windy days.
  • Newly planted, marginally hardy trees and shrubs can be protected during their first couple of winters by wrapping them in burlap.

 Picture3Vegetable Gardens:

After harvesting, clean out all dried plant material in vegetable gardens.  Insect pests tend to over winter on the leaves of many vegetable plants.  Consider planting a cover crop such as annual vetch, clover, or rye in your vegetable garden.  Cover crops prevent soil erosion, add organic material to the soil when plowed under in the spring, and those in the legume family add nitrogen to the soil. 

Work screened compost into the soil in vegetable beds as deeply as possible

  • Late fall tilling or turning of the soil in vegetable garden beds can help control insects because it exposes over-wintering insects to winter conditions


  • When bringing houseplants and non-hardy container plants indoors for the winter, be sure to clean soil off of the outside of pots, remove dead foliage, and treat for insects as necessary in order to avoid bringing unwanted pests into your home or greenhouse.  Be vigilant for pests on these plants as indoor conditions are often conducive to outbreaks of insects brought in from the outdoors. 
  • While plants will usually adjust to indoor conditions, they may be unattractive for a few months. To lessen this response next year, begin to lower the light intensity your plants are receiving outdoors by gradually moving them to a more shady location. Ideally, you would want to begin this acclimation about one month before you will move them indoors.

Entry filed under: Fall Gardening Tips.

Garden Tips for the Week of September 6-12 Winter Garden Tips for the Gunnison Valley

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