Spring bulbs should be planted now
This is my last article for the 2009 season. While it was a slow start with frost still gracing us June 6, the season has been cool and yet seems long because of the wonderful warm September summer. A couple important things yet to do or keep in mind this fall are if you are going to plant spring flowering bulbs which include tulips, daffodils, hyacinth, alliums, anemone, or crocus, the time to plant them is when the soil temperature is 60 degrees F. This year that will probably be the first part of October, since the earth does not cool down as quickly as the atmosphere. When you plant them be sure to put some bone meal, fertilizer or compost in the holes when you plant and mix it in with the dirt so it will not burn the bulbs. The bulbs should send out roots this fall, but you do not want the bulbs to sprout and break ground in the fall.
Newly planted evergreens (yews, junipers, spruce, pines, and arborvitae) may need supplemental water to help them survive winter, particularly in drought like this past couple months. This can be a slow trickle of water from the garden hose for an hour or so per evergreen, per week, especially during the month of October, until it freezes up. This will help to prevent excess transpiration (foliage water loss due to winter sun and wind) when the roots are in frozen soil and unable to replace the lost water. Water lost through transpiration will result in evergreen foliage turning brown and bleaching.
Bright sunny days during the winter (this usually occurs in February or March) cause warming of the tissue above ambient temperature which in turn initiates cellular activity. When the sun is quickly shaded, the foliage temperature drops to injurious levels and the foliage is injured or killed. Bleaching of evergreens also occurred during these bright sunny days when the chlorophyll in the foliage is destroyed (photo-oxidized) and is not resynthesized. This happens whenever the temperature drops below 28 degrees.
There are several ways to minimize winter injury to evergreens. First: the proper placement of evergreens-yew, hemlock and arborvitae should not be planted on south and southwest sides of buildings or in places that are highly exposed to wind and sun. Second: damage can be reduced by placing pine boughs or Christmas tree greens against or over evergreens to protect them from wind and sun and to catch more snow for a natural protection. Winter injury can also be reduced by constructing a barrier of burlap or similar material on the south and southwest, or windward sides of evergreens. If a plant is exposed on all sides, surround it with a barrier, or wrap it, but leave the top open to allow for some air and light penetration.
There are anti-desiccant and anti-transpirant sprays on the market for evergreens, however most studies show them to be ineffective.
Sun scald is characterized by elongated, sunken, dried, or cracked areas of dead bark, usually on the south or southwest side of a tree. On cold winter days, the sun can heat up bark to the point where cambial activity is stimulated. When the sun is blocked by a cloud, or building, bark temperature drops rapidly, killing the active tissue.
Young trees, newly planted trees, and thin-barked trees (cherry, crab apple, honey locust, linden, maple, mountain ash, and plum) are most susceptible to sun scald. Trees which have been pruned to raise the lower branches, or transplanted from a shady to a sunny location are also sensitive because the lower trunk is no longer shaded. Older trees are less subject to sun scald because the thicker bark can insulate the dormant tissue.
Sun scald can be prevented by wrapping the trunk with a commercial tree wrap, plastic tree guard, or any other light-colored material. The wrap will reflect the sun and keep the bark at a more constant temperature. The wrap will also help protect the trees from rodent damage. The wrap should go on in the fall and be removed in the spring after the last frost. Newly planted trees should be wrapped for at least two winters and thin-barked species up to five winters or more.
Enjoy the remainder of our fall, and dream and plan this winter how you can improve your garden next season and think about trying something you have not done before.
Kyle Schulz is a Wadena County Master Gardener from Sebeka, and the regular gardening columnist for the Wadena Pioneer Journal.