Don't give purple loosestrife a chance to get a foothold


September 16, 2001|By Dennis Bishop | Dennis Bishop,SPECIAL TO THE SUN

Q. Several years ago, I planted a perennial plant called purple loosestrife in my flower border, but I have now heard that it is considered an invasive species. Can you tell me more about this?

A. Purple loosestrife (Lythrum salicaria) is on the federal invasive species list and the federal noxious weed list. The sale and transport of purple loosestrife has been banned in many states. It is not on the Maryland noxious weed list, so it can still be sold and transported within the state. However, nurseries cannot sell purple loosestrife to out-of-state customers, and it is illegal to transport it across state lines. Most Maryland nurseries and garden centers have voluntarily removed it from their inventory. I would suggest that you remove it from your perennial border as well.

Q. In last week's checklist, you recommended fertilizing in September. Why do you recommend fertilizing in the fall?

A. Fall fertilizing provides nutrients to plants when they need it most. Plants store nutrients, but after a full season of growing, plant nutrient reserves may be depleted by late summer. An early September fertilization gives plants the boost they need to get through the fall. A second fertilization in late fall will provide plants some additional nutrients to store for the winter. These nutrients will then be available to plants in the spring. Using this method, fertilizer is used very efficiently. On the other hand, spring fertilizer is unneeded when plants have stored all the nutrients they need during the winter. Because plants will not take up excess fertilizer, fertilizer spread in spring may pass through the soil and become a pollutant of our local watershed.


1. Summer may be winding down and temperatures may be cooling, but it can be a very dry month. Be sure to keep your young trees and shrubs watered.

2. Not sure what species of oak or maple is in your yard? Nuts and seedpods are often the best way to determine a species. Maple seedpods (samaras) and oak nuts (acorns) are abundant on many trees right now and can be used for identification.

3. Mums are starting to bloom. Keep them deadheaded to extend the bloom period.

Dennis Bishop is an urban horticulture educator for the Baltimore office of the Maryland Cooperative Extension Services. If you have a gardening or pest problem, you can call the Home and Garden Information Center hot line (Monday through Friday, 8 a.m. to 1 p.m.) at 800-342-2507. You can also e-mail questions, order publications and diagnose plant problems by visiting the Web site, / users / hgic.

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