Spring cold snap dictates gardening measures
The cool weather thus far this spring is providing more time for dormant pruning in the garden.
When pruning large limbs off trees, it is a good idea to make an undercut first. This is a cut from the bottom up, about one-third of the way through the limb, 4 inches or so away from the main trunk.
Make the next cut from the top, an inch or so outside of the undercut to remove the limb. The undercut keeps the limb from splitting and breaking off, which could damage the trunk.
Do not cut flush to the trunk, but just outside the branch collar at the base of the branch. Look for the point where the branch is enlarged close to the main trunk of the tree.
Make the cut with a sharp saw at the proper point for best results. Also, it is generally not recommended to paint the wound.
Most evergreens will not respond well to being aggressively cut back. A good rule of thumb is to avoid cutting beyond green foliage.
Yews, though, will respond to a more drastic cut back into old wood, but be patient as it may take two to three years to fill back in. Consider how long you are willing to wait for the shrub to look good again or do a more gradual reduction of the plant's branches over a few years until you reach your goal.
Complete this pruning before the new growth begins in early spring for best results.
• Protect emerging tulips from deer and rabbit damage by spraying with a repellent or covering with netting. Repellents will need to be reapplied after rain. Netting will need to be adjusted as bulbs grow and may need to be weighed down to keep from blowing away.
Deer and rabbits typically do not eat daffodils, Siberian squill and ornamental onions, so there is no need to protect these plants.
The Chicago Botanic Garden staff has used blood meal as a repellent with some success, but it is best to experiment some with different repellents to find something that works best for your garden.
• You will likely start seeing annuals for sale in garden centers. Keep a watch on the longer-range weather before planting. Pansies, one of the more cold-tolerant annuals, will be damaged when temperatures get to around 25 degrees without being covered.
It is OK to put some things out early in a pot and then bring inside on the very cold nights. The temperature threshold as to when to cover or bring in will depend on the type of plant. As a general safety measure, it will be best to cover most things when temperatures are predicted to drop to 28 degrees or lower.
Some plants for sale will be more cold sensitive and will need to be covered as temperatures drop to freezing.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.