I'm wondering when I should cut back my perennials. I live in Zone 9 and some of them have new growth coming out from the base of the plants. Will frost injure the new growth if I cut back this year's growth? Cheryl
It would all depend on which ones they are.
You need to be more specific and actually name the plants to which you allude.
Herbaceaous perennials can be cut back at the end of the growing season. It is an option but not a requirement - many gardeners leave perennial growth intact over the winter to increase winter interest or to provide fodder/shelter for wildlife. In colder winter climates, leaving last season's growth until spring can provide some additional winter protection.
In warmer zones, perennials will often produce a flush of new foliage late in the season. It CAN be damaged by frosts, but this is not typically a concern. Perennials hardy in your zone should be fully root hardy - the foliage may dieback or be damaged by late frosts, but the plants will regenerate from the roots each spring. In my climate for example, oriental poppies put out a new flush of foliage in late summer/early fall and despite several unusual and early cold snaps, the foliage still looks green, vibrant and healthy. By the end of winter, this foliage will have died back also, but the poppies will resprout again as soon as the temps warm in the spring and blooms won't be far behind.
pam - gardengal
I don't cut back my perennials just yet. For example, Mexican sage bush...it has new growth at the base, but some scraggly growth left at the top. I don't cut it back because, though it would look better, the top helps give the plant a bit of protection from desiccating winds and frosts which can zap the new growth. I cut no ornamental grasses back because they give me winter interest and sound. Also, many migratory birds come through and eat the seeds, not to mention mice and rats which eat the seeds. I should warn, I happen to love mice and rats and I'm tolerant of their presence in our native habitat garden.
It really depends on your reasons for cutting things back, or a list of particular plants would be helpful to answer the query of the frost issue.
Victoria
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