Fall is one the best times to plant trees and shrubs because of favorable weather and less immediate stress on newly established plants. While spring offers some of the same favorable weather, the impending hot summer months can add significant stress to your newly added and actively growing plant.
However, neither spring or fall planting are free of necessary follow-up measures to ensure successful establishment of woody plants and reduce the effects of transplant shock.
In my experience, lack of follow-up care is one of the most common mistakes in tree planting. In many cases, a homeowner has contacted me a year or two after planting with an ailing tree or shrub, and so many times, the actions they took (or did not take) in the months immediately after planting were the root cause of poor plant health.
A mulch layer at the soil surface is vital to easing the environmental stress on your newly-planted tree. It should be added at a depth of about 4 inches, extending well beyond the branch tips, to create a well-protected zone of soil for root expansion.
It serves to retain soil moisture, insulate against harsh temperatures (both cold and hot) and maintains a safe distance between necessary maintenance activities and the vulnerable stem or stems of your new plant.
Over the first winter after planting, the soil and mulch around your tree will settle, and it’s important to be sure the mulch layer remains adequate after these changes. Plan to check mulch at least once or twice over the winter and reapply as needed to maintain a consistent layer.
Although the stress of cold winter weather on a dormant plant is less than what hot summer weather brings to an actively growing plant after spring planting, a sensitive newly-planted root system can sometimes suffer losses from freezing following fall planting.
One of the major causes of freezing roots can come from settling soil that either leaves air pockets or further exposes the root ball at the soil surface as things settle. A protective layer of mulch really helps prevent freezing. It pays to watch for settling soil and reapply mulch to ensure adequate protection.
The same can be said for spring plantings, which also settle and can expose roots to additional heat stress, drying them out.
Although a fall-planted tree or shrub is cruising toward dormancy, it’s is still important to ensure adequate soil moisture by watering as needed. Water your tree once a week during times we do not receive adequate rainfall of about
1 inch each week.
While fall typically has enough rain, there can be dry periods like the last few weeks, and it is really important to keep your newly-established plant well watered through the end of November or so.
Fall watering not only serves to support roots that immediately need water, but also works to build up soil moisture going into winter. As temperatures drop, there is much less water loss due to evaporation, which will preserve soil moisture over coming months. However, your additions now can help your tree make it through any dry periods before cooler and wetter winter weather sets in.
Along with all the do’s I mentioned above, there are certainly some don’ts in tree planting. Don’t add fertilizer at planting time, in either spring or fall. Trees rarely need additional nutrients to thrive in their new setting and are much more sensitive to soil structure than soil nutrient levels.
Spend time loosening and digging a wider plant hole as opposed to adding fertilizer. Decomposition from the nice mulch layer you added will provide more than adequate nutrient levels over time.
In most cases, don’t prune your tree or shrub at the time of planting. Open pruning wounds are an additional stress on your plant in the coming year. Avoid unnecessary pruning to limit unnecessary stress.
If your plant has one limb out of place, or a broken or damaged limb, don’t feel bad making a pruning cut or two, but pruning of the entire canopy is not recommended at planting time.
By including these recommendations, your fall tree planting will be a major success. More information about tree planting and post-planting care can be found at go.illinois.edu/TreePlantingInfoSheet.
Ryan Pankau is a horticulture educator with the UI Extension, serving Champaign, Ford, Iroquois and Vermilion counties. This column also appears on his ‘Garden Scoop’ blog at go.illinois.edu/GardenScoopBlog.