Carol O'Meara - Colorado State University Extension

Carol O’Meara – Colorado State University Extension

BOULDER COUNTY – It started out innocently enough. Strolling past a rose along my drive near the end of February, I noticed something out of the ordinary. Stooping low to get a better view, my fears were confirmed: that plant was starting to leaf out. Shocked, I started lecturing it on its life choices and logical consequences, punctuated by plenty of “what-are-you-thinking?”

Out of the corner of my eye I saw my spouse, who had come out to see what the ruckus was about. I stopped my tirade abruptly. Quietly, he said “you know you’re yelling at a rose bush, don’t you?” My response of “yes, but it deserves it,” only elicited a concerned shake of his head.

In my defense, it was leafing out in February. The warm spate jump started spring and many plants began to do things they shouldn’t be that early in the year. The question we’ve been getting in the office is: will trees, shrubs, and perennials have been badly damaged by the freeze that followed?

The most likely damage can be to spring-flowering trees and shrubs, such as viburnum, mock orange, forsythia, redbuds and other trees and shrubs that were in bud swell or bloom this early in spring. The freezing storm may also have damaged newly emerging foliage.

Fortunately, trees and shrubs have can leaf out again if the first flush of growth is damaged or destroyed. However, the show of flowers might be diminished this year. Healthy, well established trees and shrubs should not be greatly harmed and will leaf out again within a few weeks. Provide the plants with good care during the remainder of the year, such as watering during dry periods.

With fruit trees, if the tree is still dormant, don’t worry; freezing temperatures don’t harm them. But tender, swelling buds are at risk, especially flowers. As flower buds begin to swell, they deharden, become increasingly vulnerable to cold temperatures. They are most vulnerable just before, during, and after bloom. Apricots and peaches are most prone to damage.

As far as my rose and perennials go, the freeze nipped the tender young growth but roots and crowns should be unharmed. They’ll send up a second flush of growth in a few weeks.

Pre-emergent weed control is helpful in keeping weeds in lawns at bay, and for best results, plan to put it on your lawn now. The right time to apply pre-emergent weed control is mid-March to early April, two to four weeks before the seeds germinate. The early warmth works in favor of the weeds, so don’t delay.

As with all products, follow the package directions when applying pre-emergent. Regardless of whether it is derived synthetically or naturally, like corn gluten, pre-emergents need only be applied in a light layer across the lawn. Put down too much, and there is a risk of stunting the grass’ root system, causing poor performance later in the summer when heat takes its toll.

Corn gluten contains a fair amount of nitrogen, so if you opt to use it, decrease the amount of nitrogen fertilizer you put on your lawn. Too much nitrogen and your lawn mower will become your best friend, since your grass will grow so quickly you’ll need to mow often.

Colorado State University Extension, together with Boulder County Parks and Open Space, provides unbiased, research-based information about consumer and family issues, horticulture, natural resources, agriculture and 4-H youth development. For more information contact Extension at the Boulder County Fairgrounds, 9595 Nelson Rd., Box B, Longmont, 303.678.6238, e-mail [email protected] or visit