1 - Spanish broom and some other shrubs frozen to the ground will benefit from the rejuvenation pruning to restore the plants.
Q. Does Spanish Broom die all the way back, or did mine just get zapped by the super-hard freeze? They are coming back from the roots but still have dead-brown spikes sticking up. Can I safely assume the spikes would have leafed out by now if they were going to, and just chop them off?
A. This year many Spanish broom plants died to the ground. However, some gardeners had plants that lost some branches, while other branches on the same plant are now growing and blooming. If your plant is sprouting only at the base, it is probable that the branches died to the ground, or near the ground. Cutting them to the ground will result in a rejuvenated plant - all fresh, new growth with many blossoms. This same advice is relevant for most shrubs. Many shrubs such as butterfly bush, rosemary, crape myrtle, and even roses were frozen severely so that the stems above ground either died or are not capable of developing healthy new growth. Often these shrubs will sprout from the very base of the plant and produce new, very vigorous growth. The established root system is able to quickly supply water, minerals, and stored carbohydrates to produce a new, very attractive top portion of the plants. This is the principle of rejuvenation pruning, but this year the winter forced us to rejuvenate our many shrubs. One caution is necessary. Some plants are grafted onto a rootstock that is a different variety than the top of the plant. This is especially true of hybrid tea roses and many trees. If the plant sprouts from the base, the new plant may or may not be the desired variety. This is especially true for hybrid roses, so watch to see that the new growth is what you want. In this case you may either keep the rootstock (usually less desirable) variety, or dig the old plant out and replace it.
Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: email@example.com, office: 505-865-7340, ext. 113.
For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.
Please copy your County Extension Agent and indicate your county of residence when you submit your question!