Does October, November, and December sound like gardening months to you? Well they should! While most people are raking leaves and winterizing their gardening tools, I’ll be out planting dozens of perennials and dividing others.
Fall is one of the best times to plant flowers in the garden. The cooler temperatures and moist Autumn soils mean less heat load and water demands on new plants. And even though above ground growth may cease, roots will continue to grow well into Winter better establishing the plant for Spring. Also, there is reduced competition from weeds and pests.
How late can you plant flowers, trees, and shrubs?
You can plant perennials in Fall right up until the ground freezes. For trees and shrubs, as long as you are not on the ‘northern’ limit of their range, you can also plant until the ground freezes.
Although cooler temperatures may not seem like ‘gardening’ time to you, anything you plant in Autumn will have a couple months to get established before Winter fully sets in. In fact, you can plant perennials, trees, and shrubs right up until the ground freezes. Personally, I probably plant more flowers in Fall than I do in Spring!
In this article I’m going to cover 12 reasons Fall is a great time to plant perennials, trees, and shrubs. So stick with me and rethink why you should still be gardening in Autumn!
1 – Stronger root systems in Spring
While the outdoor temperatures of fall may arrest above ground plant growth, the soil will stay warm for a long time after, meaning the roots can continue to grow. Roots of plants that are planted by mid-Autumn will still have 3-6 weeks of growing time.  Even when the above ground portion of plants go dormant, the roots will continue to grow and establish themselves. Furthermore, these roots will further grow in early Spring before any above-ground growth emerges, making for a better established, stronger plant in Spring.
2 – Less water demands
The cooler outdoor temperatures in Spring mean less water demands on your plants. Plants need water during hot temperatures to cool themselves. But the cooler soils and outdoor temps of Autumn mean this water demand is very low, making it easy to establish plants. Thus, as the soil tends to stay more moist in cooler outdoor temperatures you don’t need to worry as much about providing supplemental water. The new plants will keep right on growing with less stress. 
3 – Easier to work in cooler temperatures
The cooler Autumn days are a pleasure to work in rather than the dog days of summer. Not only do the plants need less water, but you don’t need to worry about keeping hydrated as much either! It is much more comfortable to be working in mild 50-60 degree weather rather than 90 degree heat!
4 – Less competition from annual weeds and other plants
In Autumn, most weeds are on their way out for Winter and so most annual weeds won’t be in competition with your plants for nutrients, water, or space. So you can place your perennials where you want without worry from overcrowding or competition from other weeds, making Autumn a perfect time to plant.
5 – Less garden pests
By Autumn most plant eating insects have moved on to a new life phase. So, you won’t have damage or stress on your new plants from leaf eaters. This further reduces stress on the plant and allows it to better establish itself.
6 – Less damage from rabbits and deer
As the roots will continue to grow after the above ground portions of the plant go dormant, you will be gaining much growth on your plants while not needing to protect the foliage as long. There will only be a limited window for deer and rabbits to browse foliage. So, why does this matter?
Well, over I’ve observed over many years that when you transplant a new plant into the garden, the deer and rabbits take notice. In fact it is almost like they can’t wait to sample that new species of flower! But, if the plant emerges in Spring with everything else, it will be less bothered or browsed by herbivores. I can’t explain why this happens, but can tell you that I’ve noticed it repeatedly for many years.
So, getting new perennials out into the garden in Autumn means that they won’t need as much protection, but their roots will still grow until the ground freezes. Then, the following Spring the plant will emerge with everything else, and be less prone to be specifically targeted by deer and rabbits!
If you are planting larger perennials from pots, then they probably don’t need any supplemental protection from rabbits or deer as they will have larger root stocks. If you are planting smaller plugs though, you should still apply some protection to keep the rabbits and deer away. In fact in my Fall plants I will only spray Liquid Fence once or may twice before Winter sets in.
7 – Discount plants at nurseries
Most nurseries don’t want to overwinter plants. In Autumn they put their trees, shrubs, and perennials on deep discounts. You can usually buy a whole lot of plants for 50% off or more as they are looking to off-load their inventory.
Tip – you can find Native Plant Nurseries by using our directory, which contains over 500 Native Plant Nurseries in the United States.
8- Easier to plant rather than overwintering
If you grow a lot of your plants from seed, you are probably aware that overwintering flowers, trees, or shrubs in pots can be tricky and take up space. To avoid that, you can simply find a location and plant them. It is much easier to get a small plug established in Fall rather than Spring.
While some plants can be overwintered in pots just fine, many woody trees and shrubs will die if their roots freeze solid. So, to avoid this fate, do them a favor and plant them!
9 – A great time to divide your perennials
Autumn is a great time to divide your perennials. Dividing a plant can be very stressful, but the lower outdoor temperatures and cooler, more moist soil allow the plant lots of time to recover. If you’ve never thought of dividing perennials before, you can see several of our step by step guides here, here, and here.
10 – Perfect time for transplanting and relocating plants
Those cooler Autumn temperatures aren’t just better for dividing plants. You can move or relocate plants easily during these cooler temperatures. Just try to wait until the plant is going dormant and has finished seed production (particularly with Asters).
This mainly works for plants with fibrous root systems like Echinacea, Rudbeckia, Monarda, and some Asters. Simply try to dig up as much of the root ball as you can, and go drop them into their new home.
11 – Less humidity
Autumn often brings drier air along with it’s cooler temperatures. While drier air often means more water is lost via transpiration on the leaves, this is counter acted by the cooler temps and moist Autumn soil. But, this drier air will mean less fungus or foliar disease that can attack your plants. Thus, there is even less stress on plants.
12 – Give soils a boost by adding some organic matter
Applying compost to flowers, trees, and shrubs is a great way to give them a little boost of nutrients. But, not everyone has a compost pile or a ready supply. But in Autumn, when planting new plants we don’t actually need compost to give the plants a boost. We can simply add some leaves into the hole, or apply a nice layer of leaf mulch around the newly planted flower.
Over the Winter the leaves or twigs in the hole will naturally decompose, turning into compost underground. This will give the plant a small nutrient boost next Spring, as well as increase the soil food web, making the plant’s root system better at absorbing nutrients from the surrounding soil.
 – Barraclough, P. B., and R. A. Leigh. “The growth and activity of winter wheat roots in the field: the effect of sowing date and soil type on root growth of high-yielding crops.” The Journal of Agricultural Science 103.1 (1984): 59-74.
 – Stackhouse, Jennifer. Planting Techniques, Sydney : Murdoch Books, 2012, pp194. ISBN10 – 174196752X
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