An earwig crawls on a leaf. Photo credit: Getty Images
Have a gardening question? UC Master Gardeners of Santa Clara County are here to help. Our volunteers are part of the University of California Cooperative Extension program and are trained to use research-based information to educate residents about sustainable gardening and landscaping practices specific to their area.
Our monthly “Ask a Master Gardener” column answers your questions and offers tips. Have a question? Email us at lifestyle@embarcaderopublishing.com.
I have earwigs in my garden, do they harm my plants and how can I get rid of them?
Answer: Earwigs are the second most damaging pest to plants after snails and slugs. They are beneficial as they eat insects such as aphids, but they also eat soft plants. In large populations, earwigs can cause considerable damage. They feed at night and hide in small, damp places during the day. In the evening, place tightly rolled, damp newspapers or cardboard to capture earwigs. In the morning, dispose of the paper and the captured insects. For other methods of control, see this UC Pest Notes article on earwigs.
How do you know how much moisture has penetrated into the soil?
Answer: You've been watering your yard or garden, but do you know how deep the water has penetrated into the soil? You don't need an expensive moisture meter to find out – you can use a simple probe. Use a long screwdriver, metal rod, or anything sturdy that you can push into the soil about a foot. Press the probe directly into the soil, applying firm pressure. The probe will go through the moist soil and stop when it hits the dry soil underneath. You'll then know how deep the water has penetrated. We recommend watering generously, not too often.
More information: Checking water depth
The black spots on the leaves of this rose bush were caused by a fungus. Photo by Getty Images.
Why do my rose leaves look unhealthy?
Answer: Most rose problems are not caused by disease or pests.
Roses are notoriously susceptible to many diseases, including rust, black spot and powdery mildew. For this reason, they are often planted on the edges of vineyards to provide an early warning of diseases that affect the vines. However, not everything that harms roses is a disease or a pest, so don't be quick to resort to chemicals. Abiotic disorders, that is, problems caused by non-living factors, can be addressed by changing the way you care for your plants.
Dark stems may be due to sunburn. Brown leaf edges may indicate high soil salinity. Yellow leaves may be due to nutrient deficiencies. Unusual growth may be due to exposure to glyphosate, the active ingredient in Roundup. Good air circulation helps dry morning dew and prevent rust and powdery mildew.
Tips for keeping roses healthy include choosing hardy varieties, enriching the soil with compost, fertilizing regularly (but not overdoing it), irrigating directly at the base of the plant, and removing suckers (fast-growing, long-stalked stems) from roses. Prune suckers below the shoot union (the base of the rose plant above the root system where all the stems grow). This article, Roses: Diseases and Abiotic Disorders, has more information.
How can you prevent ants from becoming a problem in your yard?
Answer: Have you ever seen a line of ants running around on a tree trunk, plant, edge, or inside your home? They are probably Argentine ants, the most common species in California. These pests are attracted to the sweet honeydew excrement produced by aphids, mealybugs, and soft-bodied scale insects. They love the honeydew so much that it actually protects the scales and aphids, causing their population to grow. What can you do? Reduce the ant's food source by controlling the insects that produce the honeydew. Wrap a sticky substance such as Tanglefoot insect repellent around the tree trunk. Buy ant stakes or pre-packaged ant bait in small containers. The ants will carry the bait back to their nest and feed it to the dead ants. Here is a great resource with more information. Good luck!
The Palo Alto Demonstration Garden features more than 300 water-saving plants. Ember-Caldero Media file photo.
Have more questions? Visit us in person at the Demonstration Garden
UC Master Gardeners of Santa Clara County has eight demonstration gardens that showcase home gardening best practices and provide hands-on experience.
When we are working in the gardens, you are welcome to come by, ask us questions, and enjoy gardening with us. We also offer classes, events, and plant sales in some locations.
The Palo Alto Demonstration Garden, located at 851 Center Drive in Palo Alto, Eleanor Pardee Community Garden in Palo Alto (view map) , is one of our gardens.
Established in 2003, the garden (commonly referred to as PADG) has two distinct areas: the Edible Garden, showcasing an edible garden using a variety of seasonal vegetables, fruits and flowers, and the Water Wise Garden, showcasing a beautiful garden using native, low-water plants.
The Edible Garden was once an exposed parking lot for municipal vehicles, but is now a beautifully designed collection of vegetables, fruit trees, berries, herbs and flowers planted in-ground and in raised beds, with food grown there donated to the Palo Alto Downtown Food Closet.
The Water Wise Garden shows you how to create a beautiful, water-efficient, natural garden using California native and Mediterranean climate plants. Once established, the plants in this garden require minimal hydration during the summer and provide food and shelter for beneficial insects, butterflies and birds. There is also a lawn alternative area that shows you how to create a beautiful, water-efficient, natural garden using California native and Mediterranean climate plants.
We host Open Garden Days every Saturday from May through to October, when you can wander through our edible and ornamental gardens, ask questions and get plant and garden advice directly from our Master Gardeners. We also host gardening workshops, usually on the first Saturday of each month – join us on a Saturday morning this summer.
UC Master Gardeners Mary Collins and Betsy Fisher learn how to grow peppers and tomatoes successfully on June 26. Photo by Getty Images.
UC Master Gardener Event in June
There are several UC Master Gardener gardening events happening around the county this month, and here are some of them and a more detailed schedule of events for this month.
June 8: Container planting (Cupertino)
June 11: Cultivation of garlic and other edible onions (Saratoga)
June 11th: How to Build Healthy Soil in Your Garden (Online)
June 15: Guided tour of Marshall Cottle Park's Native Gardens (San Jose)
June 15: Culinary herb cultivation in Santa Clara County (San Jose)
June 26: Tomatoes and peppers successfully grown (Cupertino)
Want to ask a UC Master Gardener a question about your plant problem? Submit your question to the Help Desk online. Garden events and classes can be found here.
Ask questions or listen in on a Zoom Plant Clinic held the second Tuesday of each month from 7-8:30 p.m. The 2024 dates are June 11, July 9, August 13, September 10, and October 8.
You can also subscribe to our monthly newsletter of tips and events, and San Mateo residents can also find gardening advice on the UC Master Gardeners of San Mateo and San Francisco website.
