Question of the Week: December 24, 2020
“Should I prune my pampasgrass back? If so, when and by how much?”
There are two possible answers, and they’re predicated on whether there has been freeze damage or not.
Pampasgrass (Cortaderia selloana), a large evergreen, clump-forming grass, is native to temperate parts of Brazil, Argentina and Chile. It’s been a popular part of Texas landscaping for well beyond 100 years. It’s listed as winter-hardy to Zone 8 and southward, meaning that freeze dieback is possible near and north of the I-20/I-30 corridor.
If and when you see browned leaves following temperatures in the teens and single digits, that would be the only time you would want to prune pampasgrass.
Put on long sleeves, heavy pants, durable gloves and goggles to do the job. The leaf blades are razor-like and unpleasant against tender flesh. I find it easiest to gather a handful of blades together and cut them all at the same time.
Do your trimming before any new growth begins for the spring. You don’t want to cut green blades unless you’re prepared to look at the cut ends for the rest of the growing season.
Otherwise, don’t prune pampasgrass at all. Let it form its huge clumps. The plants need to store all the energy they can in order to produce those huge flower stalks each fall. Trimming off green foliage only slows that down.