CO-Horts

Planting Perennials in the Fall

By Sherie Caffey, Horticulture Coordinator, CSU Extension-Pueblo County

Newly transplanted Apache Plume

    Don’t put those shovels and gardening gloves away just yet! There is still a little time left to plant perennials in your landscape.

    When you think of planting new plants, Spring definitely comes to mind. Fall, however, can be a good time to plant as well, and many garden centers will be having end of season sales at this time, so you can score some great deals! As long as the plants have time to establish good roots before the first killing frost comes, they should be able to survive the cold season. Down here in Southern Colorado, we won’t expect our first frost until mid to late October, so there is still time.

    If you are going to do some fall planting, don’t forget the mulch! Fall planted perennials are more susceptible to frost heaving in the soil due to their smaller root systems. Mulching your new plants will stabilize the soil temperature, minimizing the effects of heaving. The mulch will also prevent fluctuations in soil moisture, which will make your new plants happy as well.

    When you dig the hole for your perennials, make sure it is wide enough, you want there to be plenty of room for the roots to spread out and grow. You can amend the bottom of the planting hole with some good fluffy garden soil. Be sure to mix the soil in with the native soil to prevent an interface issue. To give your plant’s roots a boost, you can also add some root stimulator, or beneficial mycorrhizae to the bottom of the hole.

Loosened root ball

Bound root ball

    To give those roots a fighting chance, be sure to break up the root ball a bit. Roots can become bound in pots and will have trouble spreading out in the soil. You can score the root ball with a knife or the plant marker in a few places to loosen the roots. I prefer to gently dig my fingers into the root ball until it looks loose and messy. Remember, good strong roots will lead to a good strong plant, so do everything you can to make sure they have a good start.

    Even if you are planting xeric plants, they will need to be watered when they are young. After planting, give the plant one good round of water, wait 5 or ten minutes, and give it another. This will ensure that the water is soaking all the way down to where the roots need it most. Depending on conditions, the plants will need to be watered every so often until the roots become established. You should also water throughout the fall and winter when there is a warm spell and has not been precipitation in a few weeks.

Fall transplanted perennials

    I hope you are inspired to some last minute planting before the cold season begins. Happy Fall and happy planting!