When and how to divide ornamental grasses

When and how to divide ornamental grasses

Last Updated on April 18, 2020 by John

Ornamental grasses make for a wonderful addition to any garden and they can be divided very easily and most are best divided every few years to keep them looking their best and vigorous which is of course when they look there best.

Dividing grasses serve multiple purposes. It helps prevent your plants from losing their overall health by getting too old and scraggly and of course, promotes new fresh growth. It also helps reduce the size of a clump if you have ornamental grasses that are taking over a particular area and bullying away other plants nearby. You can also use this process to divide your grasses so that you have more plants you can cultivate in other areas.

When to divide grasses by type

No matter the reason, you can divide multiple types of grasses. It’s best to divide cool-climate grasses once every 3-4 years, these include grasses such as carex, Hakonechloa and Stipa and is best done towards the end of winter or the beginning of Spring as soon as they come into their growth.

If you have warm-climate grasses such as Miscanthus, pampas grass and Phalaris you may have noticed they usually start to shoot a little later usually around May, don’t divide until the end of spring, once the growth starts.

What if you don’t know what type of grass you have

If unsure what type you have, it’s simply best to wait until your grasses start to come into growth in spring and then divide.

How to divide grasses

Step 1

When you are dividing grasses you want to use a very similar method as you would when dividing other types of clump-forming plants. Start by lifting the grasses out of the ground which will probably require a gardening fork or a spade.

When you do so, try not to disturb the roots as much as possible but don’t worry too much as most grasses are very forgiving. Of course, you want to shake everything clean so that you can get clear visibility and access to the clump so that you can make a successful division without causing too much damage.

Step 2

The first thing to note that if you are planning to dividing pampas grass, they will be plenty of growth, cut this back fairly hard before dividing. This will ensure it focuses on forming new roots when divided but also make it much easier to divide.

Split the clump using whatever tools you have on hand such as gardening forks inserted back-to-back right in the middle and using them to prise the clump apart. This is a good way to prise apart the clump as may are very tough and difficult to separate. Alternatively, you can simply cut through the middle with a gardening spade, and axe, or a sharp knife or even a saw.

Smaller grasses can usually be divided by hand 

If you are growing smaller glasses such as Ophiopogon ‘Black Dragon’ you might be able to simply tear apart the pieces by hand.

Helpful Tips: 

During this process, you want to keep your divisions as big as possible and you want to pot them or plant them back into your garden immediately.

You can also plant them into pots, we recommend using a soil-based potting compost such as Johnn Innes potting compost.