With the arrival of autumn comes specific activities and opportunities that gardeners should be aware of. While I have addressed the subject of fall gardening tasks in previous articles, one of the positive outcomes of this unfortunate pandemic is that more people are gardening than ever before, so I hope a portion of you may be new to the gardening scene. Of course, we always have something to learn no matter how much we know so I am certain I can share some good thoughts for the more seasoned gardeners out there as well. Let’s take a look at some of the most important things to know and do in the garden this time of year.
First, I think it is important to define what “fall” is in terms of the garden/landscape. Fall begins in mid-August when we generally begin to get more regular rainfall and cooler weather conditions. This triggers the ideal time to plant and improve lawns. Warm soil helps germinate grass seed quickly and establish new grass before winter sets in. As you read this we will be at the tail end of the “ideal” lawn planting season, but you can still plant grass seed with success up until the ground becomes too wet to work in. Now is an ideal time to fertilize your lawn to help improve the color and thickness of your turf. As we get into November you will want to lower the blades of your mower and cut the grass down to 1.5” to eliminate snow mold fungus in winter. Over the past few years, our lawns have continued to grow right up until Thanksgiving, so putting the mower away early has not been an option.
This is a time that we avoid pruning and fertilization of landscape plants that are naturally slipping into dormancy. Pruning and/or fertilizing now could stimulate new top growth that would not have time to harden up before winter freezes arrive. Plants will shut down by mid-November and dormant pruning can resume up until new growth emerges in early spring. There is also a great benefit from late fall fertilizing as plant roots continue to grow and develop well into the new year.
Perennial plants can be cut down either in fall or spring depending on your preferences. For some, dried foliage/flowers provide winter interest while others prefer to maintain more tidy appearances. One thing to carefully note, there are a few plants we think of as perennials that should not be pruned in fall. These include Butterfly Bush, Lavender, Russian Sage, Roses and Thyme. These sub-shrubs are distinctive in that their inner stems will remain green all winter long providing energy reserves for plants to call on during the winter season. If in doubt, just check the end of a cut stem to determine if you are working with a perennial (brown core) or a sub-shrub (green core).
Most all who garden know that fall is a great time for planting but there are some limitations to be aware of. We already noted that grass seed is best planted in early fall but can be successfully planted much later provided you realize germination may be delayed until as late as next spring. Planting of most trees and shrubs can continue right up until the ground is too soggy to work in. A common misconception is that temperatures shut down fall planting when it is really the soil moisture that prevents proper planting from taking place. Working in/walking on wet soils eliminates much needed air pockets from soil structure thus reducing the future penetration of moisture, air and root penetration.
While we can plant most trees and shrubs throughout the fall, that does not mean all plants can be transplanted or harvested at this time of year. There are many plants that can only be dug/harvested/transplanted during the spring season. These include Oak, Cherry, Dogwood, Willow and Redbud. These plants can often have limited availability during the fall season, but the increased production of container grown plants has helped fill this need.
It is best to finish all perennial plantings by mid-October to allow plants to root-in well before winter hits, but we still find ourselves putting them in landscape installations later that we prefer. When we do, we add additional mulch and look to tamp them down in mid-winter during cold periods where “frost-heaving” may occur. For the same reason cold weather wreaks havoc on our roads and driveways, so it does for newly planted landscape plants. Simply tamping down the root zones during cold snaps can save late fall planting from being exposed to severe winter cold. Personally, I prefer mild winters when frost heaving is not an issue!
As we enter the end of the season we may not be thinking about drought stress, but it can be a very real concern. Landscape plants are as sensitive to drying out in winter as they are in summer and, in some cases, even more. Look out for plants that may be located under over-hanging eaves of your home, under/near existing trees or in containers, and water them well before you stow away your garden hoses and shut off outdoor faucets.
Fall is an ideal time to begin to improve your vegetable garden for next year. Thoroughly cleaning away all remaining plant debris (that may harbor disease/insects), adding compost, planting a cover crop and eliminating weeds are all important tasks that will make next year’s garden more productive. Now is also the time to plant garlic for next summer’s harvest.
It may seem silly to some to mention that Tulips, Daffodils and other spring flowering bulbs should be planted now, yet there are dozens of customers who come into the store looking for these plants in spring when they are in bloom. Spring bulbs do not like heavy clay or wet soils, so proper bed preparation is needed for best results.
We are well into Mum season with the “season-extender” varieties now just beginning to bloom. One of the most common misconceptions of fall planting/decorating is that Mums bloom for the entire fall when the fact is that there are many different stages of Mum types that together cover the entire fall season. The Mums that are blooming in late August will not be blooming in November. There are early, mid, late and season-extender varieties in all flower colors and shapes. These new Mum varieties are easier to grow than the types that were available years ago, but they are not nearly as hardy. Mums are not considered perennial plants but “hardy,” which means maybe they will survive the winter and maybe not. Naturally the earlier in the season they are planted and the better the soil they are planted in, the better the roots will grow and the more likely they will be to survive the winter. To help ensure their survival, cut the plants to the ground after they have frozen and cover with a 6-10” layer of mulch to protect them from winter cold.
A couple more common questions we hear this time of year... yes, it is important to clean up fall leaves that may harbor insects and pests that cause damage to landscape plants and lawns. You should treat your houseplants for insects before you bring them indoors, protect the trunks of your young trees from deer rubbing, store your glazed pottery in a dry place and clean/sharpen your garden tools.
Fall provides gardeners the opportunity to look back with pride at what they have accomplished and look ahead to what improvements they want to make in the years to come. Next year’s success begins with efforts made today, so enjoy everything you do knowing the joy it will bring to your life tomorrow.
Now go outside and have fun in the dirt!