Here are this week’s gardening questions and answers, provided by Parker County Master Gardeners. To submit a question, send it to email@example.com. For more information about Parker County Master Gardeners, or to become a member, call 817-598-6096 or visit www.pcmg-texas.org.
I have rosemary and lavender in my herb garden. After all the ice melted, I noticed the top half of the plants died. Should I prune them now?
Ice storms will freeze the tops of many evergreen herbs such as rosemary, lavender, winter savory, salad Burnett, tarragon and thyme, but pruning now is not recommended. If we get another hard freeze, pruning will just set the plant back further, and might even kill it.
It is recommended that a first-year plant be covered from all freezes during the first winter. Trailing rosemary is even less tolerant of freezing than the standard variety. During hard freezes lasting several days, trailing rosemary definitely should be covered.
When is the best time to prune my shrubs?
As a general rule of thumb, prune spring-blooming shrubs immediately after blooming; and prune those that bloom in summer and fall in late January or early February.
Evergreens can be pruned any time, but in most cases need only light pruning if at all. Shrubs should be judiciously pruned to remove dead branches and improve the appearance.
It’s not necessary or even desirable that all plants be pruned exactly alike. Plants that have multiple stems, like nandina, should be pruned by removing about one-third of the canes at ground level, removing the oldest canes only. Shape the rest of the plant so that it is pleasing to your eye.
Remember that any pruning will stimulate new growth. Thinning the interior of a plant will cause it to grow taller, while topping a plant will result in a more bushy growth. It is important to note that while some shrubs benefit from topping, others are actually compromised by this practice. This will be discussed in more detail in our article next week.