How do I get rid of oxalis growing in my creeping thyme ground cover? I've tried and tried to pull it out, but I am losing the battle.
Yellow oxalis, O. corniculata, also called yellow or creeping wood sorrel, spreads quickly by seed, says Sacramento County UC master gardener Bill Pierce. Ripe seed capsules can propel seed a distance of six feet.
This plant has green cloverlike leaves, but some strains have purplish leaves. There are no selective herbicides that will kill only this plant and not harm adjacent plantings. It must be dug out.
Do not allow the oxalis to set seed. Several weedings may be necessary because new plants will grow from any stem segments that remain in the soil.
Surflan and Herbadox are two preemergent herbicides that will keep the seeds from sprouting. Check labels to see if the product you choose is compatible with plants where the oxalis is growing.
For more information on creeping wood sorrel, send a self-addressed, stamped 42-cent business-size envelope to PN 7444, UC Cooperative Extension, 4145 Branch Center Road, Sacramento, CA 95827. The information is also available at www.ipm.ucdavis.edu.
I have a large concrete wall I want to cover. Can you recommend a fast growing evergreen vine for the Roseville area?
English ivy, Hedera, is one of the fastest growing vines for covering walls, says Sacramento County UC master gardener Bill Pierce. It needs no support and there are many leaf forms from which to choose. Here are a few:
• Clytostoms callistegoides (formerly Bignonia violacea), or lavender trumpet vine, has shiny leaves and attractive flowers; it only has tendrils so you will need to add wire to your wall to give it something to fasten to.
• Macfadyena unguis-cati, cat's claw, or yellow trumpet vine, will cling to a wall; it is a vigorous vine and has been used on several of the freeway bridges along Highway 50.
• Ficus pumila or creeping fig is self clinging but does not produce flowers.
Other vines such as Bougainvillea and Hardenbergia are not frost-hardy enough to trust them to cover a wall.
Our backyard is a mixed planting of trees and shrubs with ground cover, some annuals and perennials. I think it's OK, even desirable, to leave some leaves on the ground. My better half says leaves need to be raked up to prevent slugs and snails. Who is right?
You are both correct, says Sacramento County UC master gardener Bill Pierce. Retaining the leaves will help promote more moisture in the soil for the health of the plants; the decomposed leaves will act as fertilizer for the shrubs and trees, and the additional moisture and cover will provide ideal conditions for slugs and snails to multiply.
Pierce says the "greenest" approach would be to protect the perennials with snail bait such as Sluggo and let the leaves enrich the soil.
For a copy of the UC publication "Compost in a Hurry," send a self-addressed stamped 42-cent business-size envelope to Publication 8037, UC Cooperative Extension, 4145 Branch Center Road, Sacramento, CA 95827.
GARDEN QUESTIONS?
Questions are answered by master gardeners at the UC Cooperative Extension services in Sacramento and Placer counties. Send questions to Garden Detective, Home &Garden, P.O. Box 15779, Sacramento, CA 95852. Send e-mail to h&g@sacbee.com. Put "garden detective" in the subject field and include your postal address. To contact your UC Extension directly, call:
• Sacramento: (916) 875-6913; 9 a.m.-noon and 1-4 p.m. weekdays
• Amador: (209) 223-6838; 10 a.m.-noon Tuesday through Friday; e-mail ceamador.ucdavis.edu.
• El Dorado: (530) 621-5512; 9 a.m.-noon weekdays.
• Placer: (530) 889-7388; 9 a.m.-noon on Tuesdays, Wednesdays and Thursdays or leave a message and calls will be returned.
• Nevada: (530) 273-0919; 9 a.m.-noon Tuesday through Thursday or leave a message.
• Yolo: (530) 666-8737; 9-11 a.m. Tuesdays and Fridays, or leave a message and calls will be returned.
