Fall Planting: Opportunity Knocking
There is an overall consensus that fall is an excellent time of year to plant trees and shrubs, but what about forbs (herbaceous perennials) and grasses?
There are many benefits to planting in the fall. From an aesthetic point of view it is the perfect opportunity to edit your garden. Rather than relying on memory to assess the effectiveness of your design, as you would need to do in spring before your garden wakes up, the patterns created by your plant combinations are still obvious and so are any bare patches. It is easy to identify which species have been struggling in a given spot and which ones have become overly enthusiastic.
There is also the advantage of reduced maintenance and care after installation. As the temperatures cool down and fall rains increase in regularity, the need for supplemental watering is all but eliminated. And, should the conditions become adverse due to a late season dry spell, the plants will draw their energy back into the roots and enter dormancy early without any compromise to their long term well-being.
Possibly the best argument for fall installations is that they give plants a head start for the next growing season. It also takes the guesswork out of deciding how early is too early to plant in spring. Your plants will adapt to your local conditions and emerge according to their biological clock. No need to worry about purchasing plants that might or might not be winterized and hardened off, or worrying about protecting them against unpredictable late freezes.
There are, however, some concerns that you should be aware of before planning a fall planting. Unlike woody plants, herbaceous plants can lose up to 75% of their root mass over winter when they senesce (when the above ground parts die back) as part of the natural process of dormancy. This can affect the survival rate of some young plants depending on how late in the season they are installed and how much time the roots have had to establish in the native soil.
Fall Planting Tips:
- As fall progresses and you reach the end of the recommended planting window (around the time we can expect the first hard freezes) heaving can become a concern: freeze/thaw cycles will have a tendency to push plugs out of the ground if their roots did not have enough time to firmly anchor thee plants in place. However, if you keep this in mind before planting, heaving can be counteracted easily by planting a little deeper than conventional wisdom would otherwise dictate: the crown of the plant should be ¾ to 1” below the level of the soil rather than flush with it.
- Cool season plants have the longest fall planting window and can be planted as late as a couple of weeks after first frost without much risk. As a general guideline, these plants include fall-bloomers such as many asters, goldenrods, etc, and also spring bloomers such as beardtongue, Jacob’s ladder, alumroot, most sedges, and many other plants. Look for the blooming periods, and if they are in spring or fall, they are likely perfect candidates to be planted late in the season.
- Warm season plants can also be planted in the fall. However, for better results, they should be planted on the early side (4 to 8 weeks before the first expected freezes) to ensure that the roots have enough time to establish before the cold weather sets in. With few exceptions, warm season plants include true grasses (as opposed to rushes and sedges), and many of our favorite summer bloomers such as butterfly weed.
- To see a map of the average date of first frost for your area, see our resource page.
What’s up with squirrels?
As a side note - and this is entirely anecdotal - whenever I have planted in the fall, all the squirrels in the neighborhood seem to have spread the word that they could find a stash of nuts underneath my new plant! So, regularly check your new plants through fall and winter. If any of them have been dug up by squirrels or other critters, plop them back into their holes at your earliest convenience. They will be fine!
Claudio Vazquez co-founded Izel Plants in 2009 to fill the gap in online information about native plants that was pervasive at the time. With an initial focus on describing horticulturally available native plants, Izel Native Plants has since evolved into one of the top destinations for purchasing native plants online.
