How to divide Ninebark (Physocarpus opulifolius)

In this article we will learn how to divide Ninebark (Physocarpus opulifolius). Propagating by division is one of the easiest methods to multiply plants and one of my favorites.

In general, this method is done by lifting the plant and separating it into parts near its base. The idea is that each new division has roots and shoots forming a new complete plant.

In this article

Can you divide a ninebark?

Ninebark sprout many shoots from their base and are excellent candidates for propagation by division.

There are numerous varieties of Ninebark and these shrubs are highly appreciated for the color of their leaves and their flowers.
There are varieties with lime green leaves to varieties with almost black leaves. These dark varieties makes perfect subjects for garden themes like The Coffee Show Garden, and awarded garden designed by Kirsty Wilson.

Ninebark (Physocarpus opulifolius) flowers

Let’s see the step by step.

For the demonstration in this guide I used a plant that has been growing in a pot for some time. The same principles explained here can be applied to larger specimens growing in the ground.

Ninebark (Physocarpus opulifolius) ready to be divided

We can see the branches sprouting at the base. Typically, when we have this growth pattern, we have a plant that we can divide.

When can we divide Ninebark?

The best time of year to divide Ninebark is during their dormant period, when they are leafless. That is, somewhere between the end of autumn and the beginning of spring.

How to divide Ninebark

First we have to lift the plant to see its roots.

I remove the soil around the roots until I reach the base of the stems. This will allow me to see where I can cut to split.

Losening the soil around a Ninebark (Physocarpus opulifolius)

Since this is a relatively small plant, I’ll just split it in two. With the help of a saw, I cut the base of the trunk vertically.

Dividing a Ninebark (Physocarpus opulifolius) with a saw

For sure there are roots that will get lost, but that’s okay as this bush has lots of thin, healthy roots capable of feeding both plants.
Take this factor into account when dividing plants, before cutting check that there are good roots attached to both parts.

Ninebark (Physocarpus opulifolius) splited into two

Plant the divisions

Now it’s time to plant the divisions. The process is the same as planting any plant.

Two new Ninebark (Physocarpus opulifolius) propagated by division

I use a pot suitable for the size of the new Ninebark. I fill with generic potting compost, put the plant in place and add compost around and on top of the roots.

Planting a Ninebark (Physocarpus opulifolius)

We must not compact the roots too much, just enough for the plant to be stable in the pot.

Division of Ninebark (Physocarpus opulifolius) planted in pot

At this stage we can (and should) prune the branches of the new plants, reducing their size. This has two objectives:

Reduce plant stress and keep it in hydric balance when it starts sprouting in spring. With fewer shoots growing in the spring, you will have less transpiration and less need for the capacity of the roots which have also been reduced;
Keep the plant stable. As it becomes more compact, it reduces the risk of it being disturbed by the wind while the roots are still establishing themselves.