September Tips & Events for Santa Clara County
“By all these lovely tokens, September days are here. With summer’s best of weather and autumn’s best of cheer.” ~Helen Hunt Jackson
Monthly Tips
Quiz: What’s That Orange Bump on the Branch?
You may see something like this when you walk around your garden. You may also find it attached to a piece of wood, a fence, or on tree bark. Can you guess what this is?
Photo credit: Ying Chen
Quiz - orange bump on the branch
Fall Festival at Martial Cottle Park on October 7
7th Annual Fall Festival
Come celebrate Santa Clara Valley’s agricultural heritage at Martial Cottle Park’s annual Fall Festival. This all-ages and dog-friendly event will feature live music, kids’ activities, agricultural workshops, food trucks, and more. Our Master Gardener Demonstration Garden, located within the park, will be open. We will be offering cool-season vegetable, ornamental, and herb seedlings for sale, along with garlic, shallots, and succulents. There will be talks and opportunities to get answers to your gardening questions. Join us!

  • When: Saturday, October 7, 9 am–2 pm
  • Where: Martial Cottle Park, 5283 Snell Avenue, San Jose
  • Cost: Free admission, $6 parking on-site (space limited)
Growing Peas for Winter Harvesting
Our mild Mediterranean climate lets us grow a wonderful range of cool-season vegetables all winter long, and peas are a particular star. If you plant in September while the soil is still warm, peas will grow quickly and start to produce in 2–3 months. They will then continue into early spring, giving you months of sweet, tasty treats. Be sure to give them full sun, at least 6–8 hours. Vining peas need a trellis to climb. Shorter bush types can be self-supporting but benefit from a little support to keep them upright once the peas start forming. Choose varieties resistant to powdery mildew if you know that’s a problem for your garden.
Growing Peas for winter harvest
Photo credit: Robert Owen Wahl
Plant Winter and Spring Ornamentals Now
Salvia greggii -Autumn Sage
Fall is the best time to plant most ornamentals in California. The soil is warm but not hot and winter rains are just around the corner. These conditions are ideal for promoting root growth and giving plants a strong start in your landscape. Since ours is a Mediterranean climate, select plants that grow naturally in warm summers and mild winters. They may be rootbound and look scraggly in the nursery because many are dormant by the end of summer. Don’t be deterred. Just look for healthy roots and loosen them before planting. You can also plant cool-season flowers now that bloom in the winter or others that grow slowly and then explode into fabulous spring blooms.

Photo: Plant salvias (commonly known as sages) in the fall. This one is a Salvia greggii (Autumn Sage), Brent McGhie
Why Do I Get So Much More Fruit Some Years?
Satsuma mandarins - alternate bearing
Some fruit trees bear much more fruit in one year, followed by a year of low production. This is called alternate or biennial bearing. It happens because the tree puts so much energy into producing a heavy crop one year that it has fewer resources to begin forming flowers for the following year’s crop. So what should you do? You can either decide to enjoy the biennial bumper crop or work to even things out by thinning overly heavy crops during a heavy-bearing year. See the link below for details about fruit thinning, including what varieties should always be thinned and the impact on alternate bearing.

Photo: Satsuma mandarin, which can be alternate bearing, Allen Buchinski
“Snake Oil” for Gophers?
Ultrasonic gopher deterrents claim to use high-frequency sound waves to scare gophers and other pests away from your yard or garden. But do they really work? UC scientists conducted research trials to find out, and their results showed that the devices weren’t effective. The same applies to vibrating stakes, commercial repellents, and aromatic plants. Even installing owl boxes isn’t likely to prevent plant damage, and fumigation isn’t effective. So what can you do? Trapping is the most effective gopher control method. Learn more using the link below.
Gopher emerging from burrow
Photo: Botta’s pocket gopher emerging from its burrow, Charles Hood
Quiz Answer: Praying Mantis Egg Case
Praying Mantis - Nymph-about 1 cm
Photo: Praying mantis nymph — about 1 cm, Ying Chen
The quiz photo is a praying mantis egg case. It can contain dozens to hundreds of eggs. Praying mantises develop through three life stages — egg, nymph, and adult. Nymphs emerge from the egg case looking like a smaller version of the adult, without developed wings. Even as nymphs, they are fully equipped to catch and prey on any smaller insects as an adult would. They will molt several times, getting slightly bigger each time before becoming adults. They are general predators in the garden, feeding on beneficial insects as well as less desirable ones.
Upcoming Events
Our monthly Plant Clinic Online is an opportunity to chat with a Master Gardener via Zoom to diagnose a plant problem. You can also listen and learn while other people ask questions. Please note that the Plant Clinic Online is now on the second Tuesday of the month (September 12), from 7–8:30 pm. Priority will be given to questions that are emailed in advance; instructions are in the Zoom registration confirmation. Registration required.

PADG Open Garden Saturdays, Saturday, September 2, 10 am–noon, Palo Alto Demonstration Garden, 851 Center Drive, Palo Alto

PADG Lawn Alternatives for Home Landscapes, Saturday, September 2, 10–11 am, Palo Alto Demonstration Garden, 851 Center Drive, Palo Alto

How to Have a Successful Fall/Winter Garden, Tuesday, September 5, 6:30–7:30 pm, Mountain View Public Library, 585 Franklin Street, Mountain View

Summer Fruit Tree Pruning, Saturday, September 9, 9–11:30 am, Guadalupe River Park Historic Orchard, 425 Seymour Street, San Jose

PADG Open Garden Saturdays, Saturday, September 9, 10 am–noon, Palo Alto Demonstration Garden, 851 Center Drive, Palo Alto

McClellan Ranch Open House: Starting Cool Season Vegetables Demo and Tour, Saturday, September 9, 10 am–noon, McClellan Ranch Demo Garden, 22221 McClellan Road, Cupertino

Waterwise Landscaping - 3-week course, Tuesday, September 12–26, 6:30–8:30 pm, Fremont Unified High School District Adult Education, 589 W. Fremont Avenue, Sunnyvale

Plant Clinic Online, Tuesday, September 12, 7–8:30 pm, Online

MCP Succulent Open House & Sale, Saturday, September 16, 9 am–noon, Martial Cottle Park, 5283 Snell Avenue, San Jose

MCP Planting California Natives for Year-round Beauty, Saturday, September 16, 10–11:30 am, Martial Cottle Park, 5283 Snell Avenue, San Jose

PADG Open Garden Saturdays, Saturday, September 16, 10 am–noon, Palo Alto Demonstration Garden, 851 Center Drive, Palo Alto

MCP The Story of the Prickly Pear, Saturday, September 16, 10:30–11:30 am, Martial Cottle Park, 5283 Snell Avenue, San Jose

PADG Open Garden Saturdays, Saturday, September 23, 10 am–noon, Palo Alto Demonstration Garden, 851 Center Drive, Palo Alto

Flower Cutting and Arranging Workshop (limited to 17 registrants), Sunday, September 24, 10 am–noon, Martial Cottle Park, 5283 Snell Avenue, San Jose

PADG Open Garden Saturdays, Saturday, September 30, 10 am–noon, Palo Alto Demonstration Garden, 851 Center Drive, Palo Alto
Check our calendar for the latest schedule of events. Videos of many past presentations are also available.
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University of California Master Gardener volunteers promote sustainable gardening practices and provide research-based horticultural information to home gardeners. Visit our website for more information including:

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