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When Is the Best Time to Plant Perennials? (Hint: It Isn't Spring!)

Kelly Lehman is the owner of Cranbury Fields Flower Farm and shows everyday gardeners how to grow amazing flowers on her YouTube channel.

Though most people associate spring and summer with planting garden flowers, Kelly Lehman prefers planting her perennials in fall. Here's why.

Though most people associate spring and summer with planting garden flowers, Kelly Lehman prefers planting her perennials in fall. Here's why.

I wanted to tell you about some of my favorite times to plant my perennials in my garden. As the owner of a flower farm, I plant flowers all year long, but there's one time of year that I've found to be best, and it might not be what you'd expect!

The Best Time to Plant Perennials Is in Fall

The number-one time of year that I love to plant my perennials is in the fall. And the reason that I like to plant in fall is that I don't have to worry too much about keeping up with the watering on those hot, hot summer days.

So if I go out to my garden and I start putting these plants in, I make sure that it's at least six to eight weeks before the ground freezes because perennials need a chance to get their roots established and get going in your garden before that hard freeze comes.

Kelly Lehman likes shopping for plants in fall, when most garden centers have major sales going on.

Kelly Lehman likes shopping for plants in fall, when most garden centers have major sales going on.

Garden Plants Are Cheapest in Fall

I spend a lot of time in my fall garden planting brand new plants because that's the best time of year to get cheap plants. If you visit your local garden center at this time of year, you'll find that a lot of the perennials are half off because they want to move their inventory and make room for things like Christmas items.

How to Find Healthy Discount Plants in Autumn

So what I'll do is I'll come into the stores and I will take a look at the plants and survey them. There's only one important thing to look for when buying perennials in fall: healthy leaves. That's right, look at leaves rather than blooms.

When shopping for perennial plants in fall, I know that the flower heads aren't that important, because I know that they're kind of past their prime. What I'm looking for is signs of super healthy leaves that look like they're going to give me a strong, sturdy plant that will come back next year. So if the flower heads themselves are looking kind of beat up, it's not that big of a deal. But if you can find some super sturdy-looking leaves, that's usually a good sign that that plant is going to come back strong the following year.

This root-bound hydrangea got too large in its pot and now has such matted roots that water can no longer get into the plant.

This root-bound hydrangea got too large in its pot and now has such matted roots that water can no longer get into the plant.

How to Fix a Root-Bound Plant

Sometimes when you buy plants at a discount, you'll find that they are root bound, and that just means that they were in the pots for a bit too long and the plant got a little bit too large. Essentially, its root system just kept overlapping until it created a whole network of roots almost like a mesh.

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These roots prevent water from getting into the plant and into the root system. This makes it easy for plants to get dehydrated, even if it's been raining and you've been watering it. Here's how to fix the problem:

  1. Tease the Outer Roots. Before doing anything else, gently tease the outermost roots with your fingers, but don't go too deep. You just want to create enough room to allow some water to break through. (In the demo video above, the soil underneath these roots was bone dry even though it had been raining out and I'd been pouring water on the top.)
  2. Soak the Root Ball. Since your plant's roots are hard and dry, you don't want to put the plant under any kind of stress. So the second step is to soak it for just a little bit. I recommend putting it in a bucket of fresh water. Don't push it down; instead, let it float down by itself, perhaps applying just a little bit of pressure. Let it absorb some of that water slowly.
  3. Gently Massage the Roots Again. Think of it like a little gentle massage, breaking up some of those roots very gently. Do this at the top and bottom of the plant.
  4. Rotate and Tease Until Submerged. As you do this, rotate your plant in the water until the root ball is almost completely submerged. You may have more luck massaging the top roots when it's submerged.
  5. Don't Soak It for Too Long. Leaving your plant to soak for too long can give it root rot. For example, you don't want your hydrangeas to ever sit in water for a long time, because then those roots get very squishy with something called root rot. That root damage then stops the plant from absorbing the water that it needs. So very fine line here.
  6. Replant! Once you can feel that there's a lot of moisture that's broke through the roots and the top system is broken up so that water can easily drip down once it's raining and then just kind of flow down to the plant, get it in the ground!

How Can You Tell If Your Plant Is Root Bound?

If you're not ready to plant yet and don't want to take the plant out of the pot and poke at the roots, here's another way to identify root rot. When I water a batch of new plants and see all the other plants perk up, it's a sign that something wrong with any plants that remain droopy or aren't looking good.

Lucy and Kelly Lehman in the peony field.

Lucy and Kelly Lehman in the peony field.

The Second-Best Time to Plant Perennials

My second favorite time to put plants in the ground is spring. You just need to make sure that you keep up with the watering. And that's important at any time of year—whether you're planting in fall or summer or spring, you need to make sure that your plant stays moist. But you don't want to soak it because if you soak it, you're going to wind up with issues like root rot, and I've done that before.

How to Tell If Your Plants Need Water

When you put your finger in the soil, if you go down about an inch or two of the knuckle test and that soil is dry, give those newly planted plants a shot of water. And if it feels wet, leave it alone.

Though it isn't ideal, it is possible to plant perennials (like these alliums) and keep them alive in summer.

Though it isn't ideal, it is possible to plant perennials (like these alliums) and keep them alive in summer.

Can You Plant Perennials in Summer?

Many people have asked me, what about summer? Everything's in the garden centers in the summertime, after all. So here's the thing...I plant all the time in summer because I find that the biggest varieties of plants come towards the end of spring and through the summer.

Yes, But You'll Need to Water More Frequently

I usually scoop up a ton of plants from my garden centers and put them in the ground in summer, but I know that I have to be super careful about keeping those plants hydrated because those hot summer temperatures come into play.

How to Keep Plants Healthy When It's Hot Out

Keep an eye on the temperature and be sure to water accordingly or provide ample heat protection (here are a few great ways to keep your garden safe during a heatwave).

Kelly and Lucy Lehman enjoying a sunny day in the daffodil field.

Kelly and Lucy Lehman enjoying a sunny day in the daffodil field.

© 2021 Kelly Lehman

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