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Tulsa Gardens Now!

December 2011/January 2012

Taking Care of Winter Damage.

As Tulsa gardens go into winter it is time to think about how to help our plants survive the vagaries of cold, snow, ice, wind, and unseasonable warm spells. We are so close to the dividing line between the frozen Great Plains and the Deep South that we can never predict which weather we will face. The following tips will help, and it is not too late to put most of them into practice.

Fall Garden Cleanup To Do Now:

• 1. Frost damage will at some point threaten our gardens, and poses the greatest threat to plants with marginal hardiness, especially if the plants have broken.
• a. To minimize the danger, avoid fertilizing and pruning in the late summer and early fall. Doing either during that time can push tender young growth that is susceptible to freeze damage. And prepare to cover marginal plants that may have broken dormancy after a warm spell. Wait until the plants reach full dormancy to prune, and avoid pruning during the wild swings of temperature in the late winter/early spring .
• b. To fix damage that has occurred, wait until the weather moderates in the spring, then remove the worst of the damage.
• 2. Winter desiccation of foliage is most noticeable on broadleaf evergreens. It can be due to high winds, to salt damage from snow melt, or to warm sunny days with frozen ground which prevents the plant from being able to take up water at the roots while losing moisture through the leaves.
• a. Minimizing drying depends upon the source of the problem. If the plants are drying out due to typical high winds or to ice-melt chemicals, the plants will need to be moved to a more protected location. Although unsightly, burlap coverings can also be used to prevent wind drying. Water the plants thoroughly on open days so that there is plenty of water available to the roots.
• b. To repair the damage avoid making things worse by waiting for more settled temperatures. Many wind-burned leaves will be pushed out by new growth. If not, many others can be hand picked. If the woody parts of the plant have been killed, prune back to live wood.
• 3. Frost heave can throw shallow rooted perennials right out of the ground.
• a. Divide and plant perennials as early as practical in the fall so that they can become well rooted before winter. Mulch up to within a few inches of the crown to keep the ground from freezing and thawing, the cause of heaving.
• b. To repair, replant the heaved plant as quickly as possible. Water it in well, and provide it with some cover. If the ground remains frozen for any time at all, pot the plant up and keep it in a moderate site until you are able to work the soil.
• 4. Animal damage can be insidious. With fallen leaves drifted up at the trunks of trees and shrubs, mice and voles can browse at the bark in peace and quiet. Rabbits cause a lot of damage as well.
• a. Place a strip of galvanized screen or mesh around the base of the plant, pushing it well into the ground to prevent tunneling attacks, and bring it high enough up to prevent rabbits on tiptoes from munching away. Be sure that the wire overlaps enough to prevent open spots, then secure with wire. This can be left in place through the year, but it needs to be checked annually at least to prevent girdling. Having put the wire in place, keep mulch pulled back from the base of the plant.
• b. Once the damage has occurred, there is little you can do except pray, and promise yourself to do better in the future.
• 5. The most serious damage, and the hardest to ignore is breakage of major limbs due to wind and/or ice. Good sense must be your guide.
• Much damage can be prevented by proper training and pruning of trees and shrubs in the course of their general maintenance. A plant pruned for strength will withstand a surprising amount of natural abuse. Certainly dead or diseased material needs to be removed. Tight crotches which are naturally weak need to be corrected. And the size of plants that could become a hazard or a problem under a snow load is best addressed in the proper pruning season.
• Once damage has occurred, take a deep breath and think. If the broken branch is a danger to life or property, it needs to be removed right away. Fallen or flattened material that interferes with basic access needs to be dealt with. Many shrubs that line driveways, for example, open out to the point where both the plants and vehicles will be damaged as the cars come and go. If the branches are simply bent over, they can slowly and gently be swept of snow, and eased back away from the drive, then secured out of the way with heavy cord or rope. If a branch is broken, it must be removed. Material that isn’t a hazard or a serious impediment is better left alone until the weather moderates and it can be safely and properly dealt with.

Winter Gardening Activies

If you have time and energy to do more gardening than the bare minimum, there is more refined work that would be useful. We have had several killing freezes. It is now time to cut most perennial dead foliage down.

Aster’ Raydon’s Favorite’ and similar asters, Solidago (goldenrod), Chasmanthium latifolia (Northern sea oats grass), Rudbeckia (black-eyed Susans), and Tovara ‘Painter’s Palette’, are all excessive re-seeders; cut the dead foliage along with the seed heads and stems and remove from garden. It is probably best not to place them in the compost pile.

Trim dead foliage down to the green basal foliage of Adenaphora (lady bells), Alcea rosea (hollyhocks), Leucanthemum (Shasta daisies), Monarda, Nepeta (catmint), Tradescantia (spiderworts), Veronica, (the upright varieties), and other perennials with foliage finished by killing freezes.

Wait to cut back these perennials: Salvia greggii, Artemisia ‘Powis Castle’, and Hibiscus varieties. These will be cut back in spring.

Ferns, whether evergreen or deciduous , should be left alone until early spring.

Trim the dead foliage of Hosta, Eupatorium varieties (Joe Pye weed), Heliopsis (false sunflower), Hemerocallis (daylilies non-evergreen varieties), bearded iris, Paeonia (peonies), Phlox paniculata (summer phlox), Phlox maculata (wedding phlox), Polygonatum varieties, Veronicastrum, and Veronica varieties (mostly upright varieties) close to ground.

Cut Canna foliage down to the ground and mulch well.

Achillea varieties may still have old bloom stems; cut them back to green growth.

Wait to cut ornamental grasses such as Miscanthus varieties and Pennisetum until they break down from ice and snow. They have good winter interest.

Clean garden tools by removing all dirt, and oil the metal parts.

Add organic mulch, making sure it is around 2-3 inches thick. Avoid putting mulch too heavily on perennial crowns as this can hold moisture and develop crown rot. Cannas are an exception to this rule as they need the extra protection.

Stay warm and cozy, and enjoy the new year.