We have many people ask us about what to cut back in the fall…
Photo credit: MTSOfan on VisualHunt / CC BY-NC-SA
First let’s address ornamental grasses. These plants give us a long season of interest especially when transitioning into fall when so many plants start to go to sleep. There are a few factors to consider when determining what to do with your grasses in the fall. If they dry nicely and are in a location that shows off their beauty during the winter months, by all means let them go and then chop them to the ground in the spring. Most ornamental grass are warm weather plants for our region and will not start to grow until well into May, so you have plenty of time to get this task done when spring arrives. There is one variety, Miscanthus sinensis ‘Variegatus’ with the wide green/white vertical striped blades that I find will pull out of the ground and be all over the yard if not cut back in the fall. If we happen to get an early snow that beats down your grasses before they can dry sufficiently, it is also better cut them down in the fall as they will not look good once this happens. We have clients with many ornamental grasses in various locations so we will remove the ones in fall that will not be seen and leave the more visible ones for winter interest.
Photo credit: ritavida on Visual hunt / CC BY-NC-SA
Fall is a great time to do dormant pruning on many shrubs. This is when the plant has stopped growing for the season and the energy has moved back to the root system for the winter. Many people make the mistake of just chopping the height of the plant but this will result and thick new growth out at the ends where it was trimmed rather than an even distribution of growth throughout the shrub. It is better to thin out the plant by removing roughly 1/3 of the thicker older branches and then go back through pruning the overall height by 1/3. Many shrubs such as Spirea and Ninebark are what we consider ‘Cut down’ shrubs and can be pruned all the way to the ground yearly or every few years for total rejuvenation. This prevents them from looking woody and sparse at the base. Spring blooming plants such as Lilacs and Rhododendron are best done after flowering in the spring as they produce their flower buds in the summer of the previous season and carry them through the winter months. If the plant is drastically overgrown this can be approached over a three season time frame for total rejuvenation while still enjoying flowers each season. If you don’t mind waiting a few seasons for the plant to re-grow sufficiently you can take a drastic approach. Lilacs can be totally cut to the ground and will produce new shoots from the roots at ground level. Rhododendron can be cut back to 18-24” with only thick woody stems remaining and will produce new lush growth from these stems and should re-grow to a height of 3-4’ producing flowers. In both of these cases you will not have flowers for a few years, but they should return within three seasons.
Photo credit: lezumbalaberenjena on Visualhunt / CC BY-NC-ND
Most trees should not require annual pruning if planted in the proper location with a good branching system from a young age. Occasionally trees can be limbed up for easier mower access and the key is simply the proper cut which allows the tree to compartmentalize and heal properly. We do a lot of pruning on smaller trees such as Japanese Maples and Crabapples in order to keep their growth restricted for smaller sites. Fruit trees are generally done in the late winter in order to prevent stem dieback or disease which can result when pruned in the fall.
Photo credit: OliBac on Visualhunt.com/ CC BY
Perennials as a general rule should be cut down to the ground in the fall. Some plants such as Coneflower produce attractive seed heads that the birds love. Sedum flower heads are attractive during the winter as the snow forms white mushroom caps. Perennials can also be cut down and cleaned up in the spring if you don’t get it done in the fall. Plants such as Hosta and Daylilies can be cut down in the fall as soon as they begin to look unattractive, but if you wait until after a couple good freezes the foliage and spent stems will pull easily without cutting.
Photo credit: Barbara.K on Visualhunt.com / CC BY-NC-ND
Weeding is one of the most important fall tasks so as to prevent seeds from dropping and establishing again the next season. Troublesome weeds such as Bittercress tend to flourish during the cool fall season but you can eradicate this difficult weed by removing before they go to see.