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UC Master Gardeners of Riverside County
April 2026
Events & Information eBlast
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UC Master Gardeners
Plant Sale
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The UC Master Gardeners of Riverside County are hosting a Plant Sale!
Come explore a wonderful selection of vegetables, flowers, and herbs—all locally grown and garden-ready! Whether you're refreshing your garden or starting something new, you’ll find plants perfect for your spring and summer landscape.
Join us for Composting Educational Workshops at 10:30 AM and 12:00 PM to learn how to turn kitchen scraps into garden gold.
Date: Saturday, April 11
Location: 3555 Crowell Avenue, Riverside CA. 92504
Time: 10:00am - 2:00pm
| Yard Tool Maintenance and Repair | |
Date: Saturday, April 11
Location: 11875 Indian Truck Trail, Temescal Valley, CA. 92883
Time: 9:00am
| Garden Tour & Vendor Event | |
Date: Saturday, April 11
Location: 2678 Harvest Crest Lane, Corona CA. 92881
Time: 10:00am - 3:00pm
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Date: Saturday, April 18
Location: Temecula Community Recreation Center - 30875 Rancho Vista Rd., Temecula CA. 92592
Time: 9:00am - 3:00pm
| Free Desert-Friendly Shade Trees | |
Date: Saturday, April 25
Location: Coachella Branch Library - 1500 6th Street, Coachella CA. 92236
Time: 10:00am - 12:00pm
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Buzz on by for the Riverside Insect Fair on Saturday, April 25, 2026, from 10 am – 4pm in-person at the Riverside Main Library. Get the chance to buzz in on Storytime fun with the Library, explore a Day in My Life with UC Riverside Entomology Graduate Students, learn how to create your own bug collection, visit the Wyland Mobile Learning Experience sponsored by Riverside Public Utilities, shop, and much more!
Date: Saturday, April 25
Location: Riverside Main Library - 3900 Mission Inn Ave., Riverside CA. 92501
Time: 10:00am - 4:00pm
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Date: Saturday, April 25
Location: 4500 Glenwood Dr., Riverside CA. 92506
Time: 10:00am
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2026 Riverside Community
Flower Show & Garden Tour
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Date: April 25 & 26
Location: 6166 Brockton Ave, Riverside
Time: 10:00am - 5:00pm
| Monarch Butterfly Surveys | |
It's time to put on our community scientist hats and rejoin our fellow concerned citizens to help conserve our endangered monarchs. Come join us at the RCRCD Greenbelt Monarch Habitat and become a community scientist gathering data on eggs, caterpillars and butterflies!
The habitat was established via a grant from the Wildlife Conservation Board of California. That grant concluded in 2023 and the RCRCD now funds the maintenance and community science program. The data collected goes on iNat, Western Milkweed Monarch Mapper and the Monarch Larval Monitoring Program.
To qualify to volunteer at this project you must watch a very short training video (to correctly identify instar stages in particular) and sign a waver. To obtain the video and waver you need to contact Michele Felix-Derbarmdiker.
Thank you for your support of this fun and important project!
Date: Saturday, April 4 & 10
Location: RCRCD Greenbelt Monarch Habitat
Time: 8:30am
| Permaculture Design Training and Certificate | |
April 4, 2026 - Food Preservation & Safety Workshop
April 11, 2026 - Class 7: Stewardship, Land Access, Earth Resources, Barter & Trade, Earthworks, A-Frame, Food Security
April 18, 2026 - Permaculture Farm Tour
April 25, 2026 - Natural Building Workshop - Cob Walls & Bottle Art
Date: Saturday, April 4, 11, 18, & 25
Location: 4500 Glenwood Drive, Riverside CA. 92501
Time: 9:00am - 3:30pm
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Eggshells,
Do they really add Calcium to the Soil?
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Eggshells, do they really add calcium to the soil? Does your soil even need calcium? The soil in Southern California generally has an adequate supply of calcium for our plants. The following are indicators your plants are suffering from a calcium deficiency.
- Young leaves are unusually small and misshapen.
- Leaves may become crinkled and torn.
- Along the margins of the leaf, brown spots will appear which become necrotic.
- Veins of the leaves eventually become brown.
- Growth of the plant is inhibited.
If your plants aren’t experiencing the above symptoms, you may not need to bother with saving all those eggshells and grinding them to a fine powder before working them into the soil.
If these symptoms are occurring, it’s a good idea to have the soil tested. Kits can be purchased from your local nursery at a reasonable sum. Another option is to have the soil professionally tested. Below are listed 2 websites you can refer to for more information.
The issue with integrating eggshells in the garden is the length of time it takes for the eggshells to decompose. The Alabama Cooperative Extension did a study in 2005 comparing coarsely ground eggshells to finely ground eggshells to pure calcium Ca (OH) 2 to agricultural lime. The results were the coarsely ground eggshells “were not much better than nothing at all.” The finely ground (powdered) performed as well as pure calcium and outperformed the agricultural lime.
If your plants aren’t experiencing the above symptoms, you may not need to bother with saving all those eggshells and grinding them to a fine powder before working them into the soil.
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Basic nutrient soil testing:
- Riverside-Corona-Resource Conservation District (RCRCD) $20 - $50
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JOIN US AT APRIL
CERTIFIED FARMERS MARKETS
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FARMERS MARKETS FEATURING
UC MASTER GARDENERS
These fun events combine shopping for fresh fruits and vegetables, gourmet foods, flowers, crafts, and many other interesting items with an "Ask the Master Gardener" information table. Master Gardeners are present to answer your gardening questions, hand out a wide range of materials on gardening topics, and present "how to do it" gardening demonstrations. This is where you can find us at farmers markets in April:
DOWNTOWN RIVERSIDE--Saturday, April 11, from 8:00am - 2:00pm at Main Street, between 5th and 6th
PALM SPRINGS--Saturday, April 4 & 18, from 8:00am - 12:30pm at 2300 E. Baristo Road
TEMECULA--Promenade Mall--Wednesdays, April 8, from 9:00am - 1:00pm, 40820 Winchester Road (Upper Level of Mall, in front of Dick's Sporting Goods)
MURRIETA--Sunday, April 12 & 26, from 9:00am - 1:00pm, Village Walk Plaza, 24480 Village Walk Place
LA QUINTA--Old Town La Quinta--Sunday, April 26, from 8:00am - 1:00pm at 78100 Main St, La Quinta, CA. 92253
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OTHER PUBLIC VENUES FEATURING
UC MASTER GARDENERS AT
INFORMATION TABLES
AKA "Ask the Master Gardener"
These are locations where UC Master Gardeners have been invited to hand out research-based information to the public and answer questions As you are out doing errands and having some relaxation, stop and get some gardening help as you enjoy these events!
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Stop by the Master Gardener Information Table at Tracker Supply:
Jurupa Valley, April 11, 8:00am - 2:00pm
Moreno Valley, April 11, 10:00am - 2:00pm
Temecula, April 11, 8:30am - 1:30pm
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Maintenance
- Cultivate and pull weed seedling now to prevent bloom.
- Check irrigation system and perform maintenance as needed.
- Check hoses as needed for fir protection.
- Prune apples, pears, any shoot tips with powdery mildew or fireblight; azaleas, rhododendrons, flowing fruit trees after bloom if needed, spring flowering shrubs, frost-damaged growth.
Fertilize
- Deciduous fruit trees and young shade trees at first leaves if not done in March.
- Azaleas, rhododendrons after flowering.
- Apply chelated iron to azaleas, gardenias and camellias if leaves are yellowing between the veins.
- Cool season turf grass.
- Cane berries, strawberries
- Citrus are heavy nitrogen feeders. Mature trees need 1 ½ lbs. N per year. Divide this amount by 4 and apply each quarter one month apart for 4 months, beginning in March.
- Fertilize shrubs and trees once during spring with slow-release fertilizer.
- Fertilize bulbs after bloom.
Plant
- Beets, carrots, Chinese cabbage, lettuce, radish, turnips
- Below 2000 ft: corn, lima beans, melons, potatoes, pumpkins, snap beans, summer squash, winter squash (marginal – only if weather has warmed). marigold, zinnia, sunflower (if weather is warm), alyssum.
- Above 2000 ft: melons, peppers, pumpkins, summer squash, tomatoes.
- California native plants! Calscape.org lists plants that grown best in every ZIP Code
Flowers
- Last chance to plant pansies, violas and primroses.
- Make a last planting of summer bulbs.
- Set out perennials.
- Many annuals may be seeds at elevations up to 1500 ft.
Lawns
Vegetables
- Transplant tomatoes, eggplant and peppers as temperatures warm.
- At cooler elevations, transplant lettuce, cabbage family, collards, and kale.
- After danger of frost, plant cilantro and two week intervals for a steady supply.
Spray
- Pears, except Comice – weak copper spray when in bloom, one to three applications for fireblight.
- Stone fruit (below 2000 ft) – Benlate, Capton, Rubigan or Rally if rainy. Wet weathers favors brown rot.
- Stone fruit (above 2000ft.) - fixed copper when buds are swollen and starting to show first color to control brown rot, peach leaf curl, pseudomonas, blossom and canker infections.
- Grapes – treat with sulfur or other fungicide when shoots are 2” to 6” long. Continue every 7-10 days until fruit start to color.
- Apples (above 2000 ft) - for apple scab use Capton, Benlate, Rubigan or Rally when apple buds first show signs of green and repeat spray every 10 days until bloom where scab is a problem. In many cases this treatment may be combined with February insect controls. (note: Rubigan and Rally are expensive).
- Check roses for black spot, mildew and rust and spray if needed
- Check roses for aphids; control with a strong spray of water or insecticidal soap.
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All fruit and nut trees: Check IPM for safe and effective sprays
- Note: All the effective insecticidal sprays kill bees and other beneficial insects. Do not spray while trees are in bloom.
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Have a Gardening Question?
Ask a UC Master Gardener!
Include as much detail as possible and any photos that illustrate your problem/question.
Email:
Riverside County: anrmgriverside@ucanr.edu
You may also call the "Ask Your Master Gardener" Helpline at 951-955-2647 with your questions.
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rivctyucmgp@gmail.com
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Copyright © 2026, UC Master Gardener Program of Riverside County, All rights reserved.
CONTACT US:
UC Master Gardener Program of Riverside County
2080 Washington Street
Riverside 92504
951-955-0170 (Main)
anrmgriverside@ucanr.edu
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