Upcoming Spring Chores
Deborah Foster, Horticulture Director
Household chores are usually dreaded by most but after a long cold winter, gardening chores are usually well received. Most of us are eager to get back outside and get a little dirty. Some of the earliest of chores will go a long way towards making our garden more enjoyable later.
Crabgrass is a summer annual grass that germinates in the spring, grows in the summer and dies out as it gets cold in the fall. Large crabgrass (also called hairy crabgrass) is a common weed in turf, and germinates from March through early May when soil temperatures reach 53 to 58°F at a 4-inch depth. Germination of this weed is encouraged by the alternating dry and wet conditions at the soil surface in the spring. Large crabgrass is similar to smooth crabgrass. However, the leaf blade of smooth crabgrass is not as hairy.
Crabgrass is best controlled using pre-emergence weed management products. These products form a layer of protection on or just below the surface of the soil. In areas where crabgrass has been a problem, apply a pre-emergence herbicide in the spring when soil temperatures approach 50°F. This usually corresponds to about the time that forsythia blooms. A second pre-emergence treatment eight weeks after the initial application may be necessary to maintain season-long control of crabgrass. It is much easier to control crabgrass before you see it than to kill it after it gets established. Pre-emergence herbicides available for crabgrass control will usually contain the active ingredients pendimethalin, prodiamine or dithiopyr. Most all of these will have "crabgrass preventer" in the product name.
Another early spring chore that is coming up soon is fertilizing trees and shrubs. Tree fertilization needs are difficult to determine based upon poor growth or off-colored foliage. Similar symptoms are also caused by prolonged drought compacted soils, girdling roots, waterlogged sites, air pollution, root diseases, nematodes and salt injury. It's important to use soil testing to determine the exact fertilizer needs of a tree.
Fertilizer that is broadcasted over the soil surface is the easiest and most effective way to fertilize. Using fertilizer spikes is not recommended. Fertilizer spikes apply too much fertilizer in one small location and not enough in others. Fertilizer should be evenly distributed under the entire canopy, but keep fertilizer 1 foot away from tree trunks.
Wait until spring to fertilize fall-planted trees and shrubs. Wait 6 to 8 weeks to fertilize plants newly planted in the spring. On established trees, fertilize in February or March before new growth begins. Apply fertilizer evenly on mulched and un-mulched surfaces out to about 1½ times the crown radius. Avoid fertilization in late summer (mid-August) since it may stimulate late-season growth that fails to harden off before frost. Do not use slow release fertilizers after July 15. Do not apply fertilizer during periods of drought.
For small trees and shrubs, use ½ cup of 8-8-8 fertilizer (8% nitrogen) per square yard of canopy cover. Do not exceed 1 tablespoon per foot of plant height if using a fertilizer with 10% or more of nitrogen (10-10-10 or 16-4-8). For large trees, measure the diameter of the trunk 4 feet off the ground and apply 1 pound of 10-10-10 for each inch of diameter. Trees less than 6 inches in diameter only need about 2 pounds of fertilizer. Water each site after applying fertilizer. Trees growing in lawns that are regularly fertilized may not require additional fertilization as long as they exhibit good leaf color and reasonable growth. Fertilizing trees with a turf grass or ground cover understory requires multiple applications at lower rates to lessen the potential for injury to the understory plants.
When following the recommendations found in a soil sample report, it is important to remember that pounds of fertilizer and pounds of nitrogen are usually two different things. A 40 pound bag of 8-8-8 contains 40 pounds of fertilizer but it only has 3.2 pounds of nitrogen.
Our most favored of all spring chores is planting new plants and seeds in the garden. If you need a source for some new and exciting perennials, annuals and herbs, come to the annual Spring Plant Sale at Lockerly Arboretum on April 6 - 8. For more details go to
or contact 478-452-2112.