June Tips & Events for Santa Clara County
“There are no gardening mistakes, only experiments.” — Janet Kilburn Phillips
Mulch-UC Division of Agriculture and Natural Resources Green Blog
Soil temperature
Mulching gets a lot of credit for holding in moisture and reducing weed germination, yet it can also help control soil temperature. Mulches moderate soil temperature, preventing fast temperature changes at the roots of plants. This improves plant growth. Organic mulches, like leaves, bark, or chipped wood, keep soil cooler. Black plastic mulch increases soil temperature. Regardless of the type of mulch you’re using, your garden soil should be getting warmer in June. Thanks to higher temperatures and more daylight hours, the soil should now be warm enough for summer planting.

Golden bee-UC ANR Repository-Kathy Keatley Garvey
Protecting Bees
Scientists worldwide continue to research and debate the various factors contributing to the decline in bee populations. Pesticides have been considered among the culprits. Neonicotinoids are broad-spectrum pesticides that affect the nervous systems of insects. When sprayed on plants, they spread throughout the plants' tissues and last for some time. You can avoid using these pesticides or avoid using them during bloom when bees are gathering pollen and nectar. Nurseries are starting to label and phase out plants treated with neonics. If you are concerned about the ornamental plants you buy, you can choose ones grown without neonics.

More:  Neonicotinoids: An Objective Assessment , University of California Nursery and Floriculture Alliance newsletter
Photo: UC ANR Repository, Kathy Keatley Garvey
Summer Squash-UC ANR Repository
Summer or Winter?
Now is a good time to plant squash in your garden, either from seed or from transplant. And, yes, you plant both summer squash and winter squash now. Winter squash just means that they can be stored over the winter. They develop a tough outer rind and have mature seeds when harvested. Pumpkins, acorn squash, and butternut squash all fall into this category and will keep for months after being picked. Summer squash are eaten when the skin is still soft. Examples are crookneck squash, chayote, and zucchini. Remember to eat your zucchini when they are small and tender and haven’t turned into baseball bats! 

Photo: Summer squash, UC ANR Repository
Peach fruit thinning-California Master Gardener Handbook
June Drop
Many gardeners get concerned when they see lots of small fruit on the ground around the June time frame. This is nature saying that it can only support so many pieces of fruit on a tree. You can also assist on your cultivated trees. Stone fruits like apricots and peaches should be spaced a few inches apart on the branch. Thin pome fruits like apples and Asian pears to two or three per bunch. If the fruit is not thinned, then individual fruits may end up smaller as they divide the tree’s energy among themselves. They may also rot as they touch each other, or they may cause branches to break from the weight.

UC ANR Publication 8047: Thinning Young Fruit
Photo: peach fruit thinning, California Master Gardener Handbook
Adult masked chafer-UC Jack Kelly Clark
June Bug?
Are you starting to see brown beetles flying around your porch light and elsewhere? Here in Northern California it is likely the adult beetle form of the masked chafer. In the grub, or larval, stage it can do damage to lawns by feeding on the roots and creating dead patches. More dramatic damage occurs when raccoons and crows dig up the lawn in search of the grubs. The UC Masked Chafer Pest Note has more information.  

Photo: adult masked chafer, UC ANR, Jack Kelly Clark
Pear fruit and leaves killed by fire blight-UC ANR Jack Kelly Clark
Fire Blight
Fire Blight is a common problem on pear and apple trees. It shows up in late spring and early summer resulting in blackened branches and twigs that have a scorched look. Ideal conditions for spreading include humid weather with daytime temperatures from 75° to 85°F, especially when night temperatures stay above 55°F. The best defense is to remove diseased twigs and branches at the first sign of the disease. Prune the infected branch about 8-12 inches below the visible damage. The UC Pest Note on Fire Blight contains photos and more information.

Image: pear fruit and leaves killed by fire blight, UC ANR, Jack Kelly Clark
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Event at Spring Garden Market 2018 by Tuan Hoang
Upcoming Events
We offer lots of free or low-cost gardening talks, workshops, and courses all over the county, as well as hosting information tables at many community events. Please join us and bring your questions!

Photo: container gardening presentation at Martial Cottle Park (Tuan Hoang)

Palo Alto Demo Garden Open Saturdays from 10 a.m.–noon (May–Oct)
Come see what we're growing at our edible and water wise gardens and get answers to your gardening questions. Feel free to bring plant pests or disease samples for identification. We're located at Eleanor Pardee Community Gardens, on Center Road near Martin Street, Palo Alto (v iew map ).

 Sat, Jun 02, 10:00 a.m.–11:00 a.m.,  Managing Pests in the Vegetable Garden , Palo Alto Demonstration Garden, 851 Center St.,  Palo Alto

Sat, Jun 09, 9:30 a.m.–11:30 a.m.,  Gardening with Kids , St. Louise Hospital Teaching & Demo Garden, 9400 No Name Uno Way,  Gilroy

Sat, Jun 09, 10:00 a.m.–12:00 p.m.,  All-Star Plants for the Native and Water-wise Garden , Bascom Community Center, 702 Chatsworth Pl.,  San Jose

Sat, Jun 09, 10:00 a.m.–12:00 p.m.,  Love Your Santa Clara County Clay , The Forge Garden Santa Clara University, 1051 Sherman Street,  Santa Clara

Sat, Jun 16, 11:00 a.m.–12:30 p.m.,  Succulents: Amazing Additions to Your Garden , Berryessa Branch Library, 3355 Noble Ave,  San Jose

Sat, Jun 16, 11:00 a.m.–11:45 a.m.,  Love your Santa Clara Clay! , Martial Cottle Park, 5283 Snell Ave,  San Jose

Sat, Jun 16, 1:00 p.m.–3:00 p.m.,  Container Gardening 101 , Sunnyvale Teaching and Demonstration Garden, Charles Street Gardens, 433 Charles Street,  Sunnyvale

Wed, Jun 20, 6:30 p.m.–8:00 p.m.,  California Native Plants for your Landscape , Calabazas Library, 1230 S. Blaney Ave,  San Jose

Thu, Jun 21, 7:00 p.m.–8:30 p.m.,  Gardening with Succulents , Palo Alto Rinconada Library, 1213 Newell Road,  Palo Alto

Wed, Jun 27, 7:00 p.m.–8:30 p.m.,  Attracting California Native Bees to the Urban Garden , Los Altos Public Library, 13 S. San Antoino Rd.,  Los Altos
Visit the UC Master Gardener Program website  for additional information including an up-to-date list of events and classes .

Have a gardening question? Contact our Hotline (for Santa Clara County residents). Start by reviewing our plant  problem diagnosis tips .
  • Mon-Fri 9:30 a.m.–12:30 p.m., 408-282-3105
  • Fri ONLY 1:00 p.m.–4:00 p.m., 650-329-1356 (Closed Dec. & Jan.)
  • Or send us your question online

The University of California Cooperative Extension (UCCE) Santa Clara County Master Gardener Program volunteers are trained under the auspices of the UCCE. Our mission is to promote sustainable gardening practices by providing up-to-date, research-based horticultural information to home gardeners.

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