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September and October Garden Checklist for Northern Colorado

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We’ve wiped the sweat from our brow and now stand in a, hopefully, cooler sunshine! Yeah! Autumn has arrived.


  • There’s no need to fertilize any longer. It would be like having a cup of coffee just before you turned in for the night. Late season fertilizing makes it more difficult for plants to wind down to dormancy.
  • Continue to mulch. Adding a good layer of soil, bark or compost around your plants will help them to weather the cold and potentially dry season ahead.
  • Keep feeding birds. Not all of them migrate and may need your help during the winter. Suet feeders should now be used while hummingbird feeders can be brought in, cleaned and stored.
  • Plan on winter watering when the moisture level is low.
  • Clean and oil your tools for winter storage.
  • Take advantage of some great garden sales at Gulley Greenhouse this season. It’s still safe to plant many perennials and the prices are of course, irresistible!


  • Fall is a great time to transplant evergreens. Be sure to amend the soil well and water thoroughly after transplanting.
  • Trees can use a big drink this time of year. If we don’t receive much rain or snow during September and October, plan to water your trees about every 2 weeks.
  • Collect fallen leaves to use as mulch in your garden. Discard any leaves that are damaged by insects, fungus or disease.


  • Harvest seeds from spent perennial blooms for spring germinating. Save in an envelope marked with the plant name and date collected. Store in a dark, dry place until ready for spring planting.
  • When planting new perennials in the fall, allow 2-3 weeks for their roots to develop and withstand a cold frost. Use root stimulator when planting to speed up the root development process.
  • Fall is a good time to divide day lilies, peonies and spring blooming perennials.


  • After August 15, hold off on any further fertilizing.
  • Use a rose collar and mulch to protect the crown of the plant.


  • Collect seed heads from basil and spinach to use for next year's crops. Allow to dry before labeling and storing.
  • Those green beans that grew too long or large with a tough pod can be left in their pod and dried for next year’s crop as well.
  • Plant cold crops in early September for late fall harvest. Cold crops include; spinach, beet greens, lettuce, broccoli and kale


  • Now is the time to plant spring blooming bulbs. They herald the onset of spring with refreshing color after our white winter.
  • Forcing bulbs for indoor blooms is easy! Stop in to learn how.
  • Summer blooming bulbs can be dug and stored for the season. These include dahlias, cannas, callas and gladiolus.


  • Rake your lawn and save any nondiseased grass clipping to use as mulch around your trees, shrubs and perennials. Or use a mulching lawn mower to add back that extra amount of clippings to help your lawn overwinter nicely.

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