Hi David: In commercial landscape settings I've successfully used a pre-emergent herbicide by the product name of Treflan. However some toxicity showed up on Rosaceae (interveinal chlorosis). Treflan is the name used for cottom farmers, can't recall what the name is for the product licensed for landscape use. Large difference in price - the cotton version is much cheaper but the active ingredients are exactly the same. I haven't tried it on geophytes in containers however. The product works by creating a barrier below soil level that kills the germinating epicotyl. Boyce Tankersley Director of Living Plant Documentation Chicago Botanic Garden 1000 Lake Cook Road Glencoe, IL 60022 tel: 847-835-6841 fax: 847-835-1635 email: btankers@chicagobotanic.org -----Original Message----- From: pbs-bounces@lists.ibiblio.org [mailto:pbs-bounces@lists.ibiblio.org] On Behalf Of David Ehrlich Sent: Tuesday, October 06, 2009 8:40 PM To: Pacific Bulb Society Subject: [pbs] weed problems Dear members, It was interesting reading the discussion about Roundup last week. I have a similar problem: pernicious weeds. I live in a townhouse alongside some birch trees. As you may know, a single birch produces millions of seed each season - every one viable! Birch seed seeps in through the tiniest cracks; it gets into everything: bedding, rugs, toweling, pet's hair; it forms windrows in the driveway. My pots get covered with a "mulch" of viable birch seed. The second most pernicious weed is Stellaria media. I'm always amazed at how much of the stuff I have to pull out of every pot. Then there are the grasses and mustards .... So you can see, I'd be very interested in finding a commercially available chemical or hormone that would prevent seeds from germinating but which wouldn't affect the growth of bulbs, whether they be dormant, awakening, or in full leaf/bloom. Thank you, David Ehrlich