Dividing Hostas: A Simple How To, When To and Why Guide

Everyone wants big beautiful hostas dotting their yard. I know I love them when they fill in my shaded areas and make the entire garden look lush and full.

So, why would you ever divide them? Not only does this make them smaller, but it can be additional work for you to do.

 However, I was curious about the benefits and drawbacks of dividing hostas, and I wanted to know how to do it properly, why I’d do it, and any tips or tricks to make it successful. The answers I found were surprising, and I decided I wanted to share it with you.

After all, the goal is to have healthy and happy hostas season in and season out, and dividing your hostas may just be the trick to getting better growth. Are you intrigued? If so, let’s dive into what I found and you can see whether you should start dividing your hostas.

Do You Need to Divide Your Hostas?

Did you know that your hosta plants will only get better as they get older if you attempt to put them in the right location? Planting your hostas in the wrong location with unsuitable soil conditions can lead to an unhealthy plant, and it’s one big reason many people choose to divide and move them.

However, it’s important to note that hostas don’t work like garden mums, yarrow, or other perennials and send out signals when it’s time to divide the plant to get rid of a dead or dying portion of it. Take giant hostas, for example.

They need at least five years of interrupted growth before you can safely divide them, even if they’re not doing fantastic where they are. If you divide them too soon, it reduces their growth potential.

But, if you want to divide your hostas to help keep them healthy or maintain a good size, you should only have to divide them once every five or ten years without hurting the plant’s growth potential. So, consider the type of hosta you have before you make a plan to divide it because you could do more harm than good.

If you look at your hostas at the center of the clump and you notice that it’s not sending up shoots or it has a bare spot, dividing them may help to improve the plant’s appearance and promote new, healthy growth.

Division can encourage new flower growth too. I like to divide my regular-sized hostas routinely to encourage a lot of flower spikes.

Maybe your hosta plants are spreading too far for the space you set aside for them and they’re getting crowded. If so, dividing them is an easy way to free up space and make sure they’re in a great spot.

You could also take this time to fill in other areas of your landscaping with the divided hosta plants, like amongst your roses.

Whatever the reason you choose to divide your hostas, give them at least a few years to grow before you do it. If it’s a giant hosta, don’t divide it for at least five years so you don’t worry about stunting the growth.

When to Divide Your Hostas

When is the best time to divide your hostas? I found myself wondering this when I decided I wanted to spread my hostas around my garden and landscape. I wanted to give them the best chances possible of taking root and thriving, so this required a little research. Here’s what I found.

Hosta Division in the Spring

If you want to divide hostas in the spring, you have just shy of a four-week window to complete this task.

You want to divide your plants before they reach full development, and you should see the hosta eyes growing up. The plant’s leaves should just be unfurling at this point.

Spring can be a very busy time in any garden, so if you miss the four-week window and your hostas reach their full development stage, it’s best to wait for summer. This way, it reduces the risks of damaging your plant and gives you a greater chance that it’ll take off.

Hosta Division in the Summer

You have a little more leeway when it comes to dividing your hostas during the summer months. The plant should be fully opened and growing. Depending on the cultivar, it may or may not have flower shoots already.

One big point about summer division is to ensure that you water your hostas very well after you divide and replant them.

Hostas generally don’t like a lot of direct sunlight or heat, so watering them well for a few weeks will help fend off shock and ensure they survive the transplant process.

Hosta Division in the Fall

Fall is the best time to divide your hostas. Just like in the spring, you get around a four-week window to complete this task.

Aim to divide your hostas in September or October, especially if you live in a northern climate. The farther north you live, the earlier you’ll want to divide.

The goal is to divide your hostas in a window that gives them between three and four weeks to establish before the first hard frost hits. Since this is a cooler and less humid climate, it’ll give your hostas the best chance of taking root and doing well in the spring.

How to Split Hostas

Now that you know the best time to divide hostas, it’s essential that you know how to split them correctly them. It’s not as simple as digging them up and cleaving them in two pieces.

There are steps you want to take to ensure that you get two or more healthy plants from each larger clump.

Before you start any digging, you want to water the day before you’re going to divide your hostas if the soil isn’t moist from any recent rainfall. This will make your entire project easier, and it can help protect the plant from shock.

Also, lay out a tarp by your workspace to put your hosta clump on.

To start, if your hostas aren’t too big, carefully dig around the entire clump, avoiding as many roots as possible.

Your depth could range anywhere from 8 inches to 18 inches, and this will depend entirely on which cultivars you have in your garden or yard.

Get your tool under the hosta and pry upwards from one or more sides. Place your hosta on your tarp. This gives you a clean working area to concentrate on each plant. It can also make it easier to see what is plant and what is dirt balls that can come off.

One thing I like to do is dig around the clump, lift it up out of the ground, and then divide it into quarters or thirds. However, if you have a hosta that is too large to work with, you can use your shovel to cliche the plant into sections without lifting the entire thing up.

I’ve found that it’s easier to use a flat spade or a garden fork to divide the clumps of hostas than a shovel. It gives you a better grip, and my accuracy levels are much better. I don’t accidentally slice through a lot of roots when I use these tools.

Whichever tool you use, carefully divide your plant into thirds or quarters. Once you get sections cut, make sure the soil has plenty of organic matter before you replant them.

I like to reset the hostas in the same location with slightly larger spacing to give the illusion of a larger plant. By summer, you won’t even know you divided it.

Make sure your divisions go to the same depth that the original plant was. So, if it was eight inches in, dig until this new division has a hole that allows it to be eight inches in.

Backfill in around your plants and make sure you water thoroughly. This ensures that your plants have adequate moisture available, and it can also reduce the risk of shock.

Quick Note About Hostas and Viruses

Most people won’t clean or sterilize their tools before they use them to cut through the hosta clump and divide the plants. However, doing so can reduce the risk of rot or fungal infections.

All you have to do is dip your cutting tools into a mixture of 50% rubbing alcohol and 50% water.

This can help remove any existing viruses that can wreak havoc on your new plants. Since the roots are more vulnerable as they re-establish themselves, it can be a good idea to clean or sterilize your tools before you use them.

This is especially true if you’re going to divide your hostas in any season other than fall because there’s a higher risk for damage, anyway.

Best Time to Divide Hostas by Planting Zone

I briefly touched on the fact that your location will affect the best time to divide your hostas, even though fall is the best. The following chart will outline the planting zones that are pertinent to hostas. There are more, but some aren’t suitable for supporting this plant’s growth.

Dividing Hostas in Pots

What happens if you prefer to keep your hostas in pots instead of in the ground? They still grow, and they can eventually outgrow their pots. However, you can also divide them and make more potted hostas to sit around your space.

Generally , you have more freedom when it comes to dividing your potted hostas than you do ones that are in the ground. You can easily move them to protect them from hard freezes.

However, this doesn’t mean that you should delay. Plan to divide your potted hostas a few weeks earlier than the ones you have in the ground.

So, instead of waiting until the middle of September in some locations, you’d divide them at the end of August.

For spring, you could divide them right when the frost goes out for the last time. For summer, you can aim for early June or even late May. Just water them thoroughly.

The same general rules apply to dividing potted hostas as it does to hostas in the ground. Carefully remove the hostas from the pots and use a flat spade to cut them into sections.

Depending on the container size, you may only be able to split them in half instead of thirds or quarters. Make sure you refresh your soil with organic matter.

Place the divided hostas into containers that are the same depth as the original one. Backfill your soil in around them and water them well.

You will want to keep them moist for a few weeks to give the roots time to establish themselves if you do this during the summer months.

Tips and Tricks

It’s always a good idea to have a trick or two up your sleeve when you divide hostas. I’ve collected several over the years, and I want to share them with you to help you successfully divide and grow your hostas for years to come.

One of the biggest threats to your new divisions is slugs. Since you make a point to water them more for a few weeks to help the hostas establish themselves, this can lead to more slugs showing up. They can leave holes in your hosta leaves if you don’t get them out.

When you divide your plants, take time to prune out any yellowing or dying foliage or stems. You can do this whenever you spot it with your hostas, but doing it when you’re dividing them gives you better access to your entire plant.

Before you put your divided hostas back into the ground, it’s a good time to mix compost in. Compost increases the soil’s water and air retention capabilities while giving your hostas more nutrients.

Add two to three inches of compost to the area and work it into the soil manually or with a tiller.

The hole should be around a foot deep and one-and-a-half times as wide as the mature hosta plant is going to be to give the roots space to spread out horizontally.

Plant your divided hosta as deep as it was originally, and add a mulch layer to the surface to help prevent weeds and retain water.

It’s also a good idea to have the best tools on-hand before you divide your hostas. I’ve found that if the clumps are 10-inches across at the base, a fork with flat blades and a shovel or spade work best.

A serrated blade works well with smaller plants in light soil, and a hacksaw is very helpful for big plants.

If this is the first time you divide hostas, have a larger bucket and a garden hose nearby to wash the dirt away from the clump before you cut into it.

This will help you see the individual plants and the rhizomes, and it reduces the risk that you’ll accidentally slice a lot of roots in half.

When I divide larger plants, I’ve found a lot of smaller root pieces attached to the major roots.

I separate these pieces off and plant them in three or four-inch pots and baby them through the first year. They’re typically ready to go in the ground by fall if you plant them in spring.

Finally, you can remove some of the larger, older leaves or cut them back when you divide the plant to reduce water loss and help minimize the shock.

Frequently Asked Questions

Why Water the Hostas After You Divide Them During the Summer

Watering your hostas for a few weeks after division helps to prevent shock, and it gives the plants a better chance of taking off and establishing themselves.

How Far Should You Plant Your Divided Hostas Apart

o create a full area, plant larger hostas 30 to 36-inches apart. Medium hostas should be 18 to 24-inches apart, and smaller hostas should be between 12 and 18 inches apart. Dwarf hostas only need 6 to 8-inches between each plant to fill in.

Do You Want to Avoid Damaging the Roots

Yes, hostas do best when you avoid causing unnecessary damage to the plant’s roots. You want to dig as much of the plant’s root ball up as possible before you divide them and be very careful not to slice through them over and over.

Closing Thoughts

So, how do you divide hostas? Now that you know the best time to divide them is in the early fall, but it is possible to divide them in the spring and summer months too.

Watering your hostas is very important if you choose to divide them in the summer to help establish the plant’s roots and encourage healthy growth. Divide each plant into thirds or quarters, plant it in composted soil, and watch them thrive.

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