Last updated on January 21st, 2020
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Ornamental grasses can be evergreen or deciduous. Knowing how to prune ornamental grasses requires knowing which of the two you have. Evergreen grasses do not loose there leaves or die back and generally just need a quick tidy up removing any dead leaves. Deciduous grasses die back to the ground or just turn brown but don’t necessarily die back.
When to prune ornamental grasses
Whether you have evergreen grasses that require some tidying up on occasion or deciduous grasses that have to be cut back annually, you should prune your grasses sometime between early spring in the middle of spring. Pruning is quite easy regardless of which you have.
How to prune deciduous grasses
Pruning deciduous grasses that don’t die back
Deciduous grasses are those that turn brown rather than lose any of their leaves so they need to be treated a bit differently when it comes to pruning. Some species such as the popular Deschampsia Goldtau or Calamagrostis Karl Foerster need to be pruned all the way to ground level at the beginning of Spring so that new growth has an opportunity to spring forth, no pun intended.
Other deciduous grasses which produce their newer growth later in the spring season can be pruned as late as April. You can also prune late for those which have structural stems remaining over winter, in which case you remove the structural stems so that the newer, greener shoots are able to come forth.
There are some varieties of deciduous grasses which share traits with evergreen grasses as they build up a lot of dead material. If you have one of these in your garden you can simply comb out the loose foliage and cut back any of the dead material in the springtime.
How to prune back deciduous grasses
When you have your deciduous grasses ready for pruning cut back any of the spent stems but take caution so that you don’t damage any of the new, greener growth that could be making its way through the crown. If there are stems and debris near the middle of the clump you can pull those out by hand being careful not to damage new shoots.
As you continue this process it’ll be easier for you to see what you’re doing with the damaged, spent stocks and flowers removed. This will make it less likely that you damaged the younger shoots. Remove any dead leaves or debris from around the crown and remove any nearby weave. When you are done you can add some mulch to the crown as well as a general fertiliser such as growmore to help it replenish itself.
How to prune Evergreen grasses
If you have smaller evergreens you can trim them back come springtime. For this, you want to remove any tips that are brown and cut back any dead leaves that you might find along the base. Evergreens don’t need hard pruning like other plants but rather can do well with simple trimming and tidying up here and there. Some of the different sedges should not be cut back completely but rather have the spent flower stalks removed similarly to deadheading. Any leaves that are scorched or disease should be removed as well.
With evergreens, there are specific varieties that benefit from a hard annual pruning one being the pampas grass. This grass should be cut back as much as you can without damaging any new growth but to do so you need to wear pants, long sleeves, thick gloves, and eye protection because the blades on each leaf have very sharp edges.
If you have an evergreen that has outgrown the space in which it was planted you can divide it the same as you divide any other perennial, remove any debris, and then replant your divisions.