Pruning Grasses
Introduction
Most grasses fall into three main groups, and pruning or cutting them will depend on which one they are.
Festuca glauca “Elijah Blue”
Cool-season grasses
These grow only when it’s cool. Usually only in spring before it reaches 75*F, and in the Fall once it cools off. They will not grow in the heat of summer.
Prune: in Fall
Example: Festuca glauca ‘Elijah Blue’ (Blue Sheep’s Fescue), Deschampsia cespitosa, Deschampsia flexuosa, and Arrenatherum elatius ssp. bulbosum ‘Variegatum’, Calamagrostis “Overdam Feather Reed”, Karl Foerster, and Pennisetum “Desert Plains”
Panicum virgatum “Shenandoah”
Warm-season grasses
These are slow to grow in spring and get going once it warms up in early summer. Their major growth and flowering happen when the weather is hot. They will usually turn shades of brown for the winter.
Prune: Method 1 - Once they turn brown in the fall, bundle or tie and leave for a winter “haystack” look and prune in early spring.
Method 2 – Bundle and tie them to form a cone, then cut them back by only a third. This helps them to hold back any winter snow that might accumulate and damage the crown. The following Spring, cut evenly across the bundle 4” height from the soil. You may use a handle pruner for most situations or a weed whacker if it’s enormous.
Example: fountain grass, Miscanthus, Schizachyrium (Bluestem), and Panicum
Acorus gramineus
Evergreen grasses
These are not actually in the grass family but they do look like them !
Prune: As needed to remove dead stems throughout the summer season. An overall main prune should only happen in early Spring. Remove the top 1/3 of old leaves only. This will help stimulate new growth. Pruning more than this is generally not recommended.
Example: Sedges, Sweetflag and Rush.
Sedges: Carex flagellifera, Carex Testacea, Carex morrowii ‘Evergold’, ‘Eversheen’, ‘Everest’, ‘Everlime’, ‘Everillo’, Carex ‘Feather Falls’, ‘Ribbon Falls’,
Sweetflag: Acorus gramineus ‘Ogon’, Acorus gramineus ‘Minimus-Aureus’
Rush: Juncus effusus ‘Quartz Creek’, Juncus patens 'Occidental Blue', ‘Elk’s Blue’
Miscanthus has a sharp leaf edge !
Tips when cutting
First of all use gloves! Some ornamental grasses can have very sharp edges and will slice through your fingers!
Wear long sleeve shirts or arm protectors.
Don’t wear shorts!
Protect your legs and use closed shoes. If you drop the pruner you could cut a toe!
You may use a handle pruner for most situations or a weed whacker if it’s enormous.
What if I don’t prune them back
An overgrown grass makes your garden look messy and unkempt, especially with the foliage brown. They can also lose their desired shape and structure.
Old dead grass stems will also make it difficult for new shoots to emerge in the spring, leading to sparse and less vigorous growth or awkward shapes. It can also harbor pests.
Dead foliage can restrict airflow around the plant's crown, increasing the risk of rot and fungal issues.
It just looks messy !
To Prune or not to Prune !
Call us if your asking yourself that question !
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GREENING NEW YORK FOR OVER 53 YEARS !
Article written by our Staff Horticulturist, Peter B Morris, BSc, MSc, MBA
All photographs used with permission @SHUTTERSTOCK
