It's Giving Tuesday, and we hope you will consider making a gift to our program. Last week we highlighted the exciting demonstration gardens our Master Gardeners are planning. Today is the day we are raising funds to make them possible! 

How You Can Help

We appreciate any amount you can give. Credit card donations will be matched if we meet the qualifications below:

• $500 to the twenty groups with the most first time donors
• $500 to the first 10 funds that secure a $500 + donation
• $500 to the ten groups that raise the most funds

Only gifts made by online/credit card donations on the day of the event qualify for the prizes. 

Please donate today! 

Now is a great time to make a tax-deductible donation to our organization! Visit https://ucanr.edu/sites/GivingTuesday/ and choose Stanislaus County Master Gardener Program.

If you prefer to donate a check, please make it out to UC Regents and send to:

UCCE Stanislaus County Master Gardeners
3800 Cornucopia Way Ste A
Modesto, CA 95358

When will you begin creating the gardens?

We plan to begin working on one of the gardens in spring, and will keep you posted on our progress through this blog as well as our Facebook, Instagram and twitter accounts (@UCMGStanislaus). Our Sensory and Pollinator Gardens will be open to everyone to visit, and used during classes and workshops on drip irrigation, low water use plants, pollinator plants, and more!   

The Autumn Equinox signals a time of change in the seasons. The weather becomes cooler, the days shorter, skies turn a softer blue with occasional clouds, summer vegetable gardens are finishing up, and deciduous trees change colors and drop their leaves. By mid-November our neighborhoods and gardens will be littered with fallen leaves.

People often rake their leaves and put them out to be picked up as trash. I have always preferred to leave the leaves for my garden.

If you take a walk in a forest, you'll see leaf layers several inches deep around trees and bushes. Fallen leaves have a complex relationship with trees and nature, providing many benefits which can be reproduced to some extent in our gardens.

Natural Mulch

Leaf litter prevents rainwater and wind from carrying the soil's nutrients away. Water trickling through the leaf layer carries essential nutrients such as carbon, phosphorus, nitrogen, and other inorganic compounds, thus replenishing the soil.

Fallen leaves have the same weed suppression and moisture retention properties of shredded wood mulch—and they're free! Where mulch is desired as a decorative element, what could be more seasonally appropriate than a pile of brightly colored fall leaves? This natural mulch also provides insulating winter cover from cold temperatures for roots, seeds, and bulbs.

A Web of Life in Leaf Litter

Leaf litter isn't just free fertilizer and mulch. It provides food and shelter for a wide variety of living things including spiders, snails, worms, beetles, millipedes, mites, toads, frogs and more—these in turn support mammals, birds, reptiles, and amphibians that rely on these creatures for food.

Detritivores (organisms that eat dead or decaying plants or animals) break up and excrete leaf litter. Fungi and bacteria then take over and complete the recycling process converting these smaller pieces into nutrients which then sustain neighboring plants. They in turn help support biodiversity by becoming food themselves.

Some creatures use leaf litter and other dead vegetation to insulate themselves from winter's chill, while others, such as earthworms, feed on the litter, breaking it into smaller pieces.

Numerous bird species such as robins and towhees forage in the leaf layer searching for insects and other invertebrates to eat. 

Raking up leaves and putting them in the trash could have the unintended consequence of removing some of next year's garden butterflies and moths, many of which are pollinators. Most butterflies and moths overwinter in the landscape as an egg, caterpillar, chrysalis, or adult. In all but the warmest climates, they often use leaf litter for winter cover. Fritillaries and wooly bear caterpillars will tuck themselves into a pile of leaves for protection from cold weather and predators. Some Hairstreaks lay their eggs on fallen oak leaves, which become the first food of the caterpillars when they emerge. Swallowtail butterflies disguise their cocoons and chrysalises as dried leaves, blending in with the “real” leaves.

Bumble bees also rely on leaf litter for protection. At the end of summer, mated queen bumble bees burrow an inch or two into the earth to hibernate for winter. An extra thick layer of leaves is welcome protection from the elements.

All of which makes leaf litter an integral part of a complex web of life.

What You Can Do

Leaving the leaves where they are is ideal but isn't always practical for gardeners. If you have lawn, you can mulch the leaves with your mower, rake them up, and place them back in the garden around trees, shrubs, and plants. Spreading some of the chopped leaves around on your lawn will also nourish it. If possible, leave some leaves undisturbed in planters since shredded leaves will not provide the same cover as leaving them whole, and you may be destroying eggs, caterpillars, chrysalis, and other micro-creatures along with the chopped leaves.

Composting leaves is a terrific way to recycle and create a nutrient-rich garden soil amendment at the same time. Some gardeners opt for shredding their fall leaves for use in compost piles. Like people who mulch their lawn leaves with a mower, consider leaving some leaves undisturbed in garden beds and lawn edges. If space allows, you could create a leaf pile, allowing it to break down naturally, or add the leaves gradually to your compost pile over time. Such efforts will keep leaf litter critters safe and allow you to benefit from the rich garden gift that falls from the trees above.

While it is ideal to “leave the leaves” permanently—for the benefits mentioned above—if you do decide you need to clean your garden and remove the leaves in spring, try to wait until later in the season, so as to give the critters that have been protected by fallen leaves over the winter time to emerge and depart.

Some gardeners may be concerned that autumn leaves, matted down by rain or snow, could have a negative impact on their perennials. However, a thick layer of leaves provides additional insulation against chilly weather and protects newly planted perennials from frost which could damage tender roots and shoots. Anyone who has spotted fragile spring seedlings popping up in the woods knows that all but the most fragile of plants will erupt through the leaf litter in spring without trouble.

So, leave the leaves. While you can't perfectly emulate a forest, your garden will be healthier and more diversified, you'll help support a vast array of wildlife, and you'll reduce the strain on landfills. 

Denise Godbout-Avant has been a UCCE Stanislaus County Master Gardener since July 2020.

Join the UCCE Stanislaus County Master Gardeners for a fun,  IN-PERSON CLASS where you will:

• Learn tips for saving water in the landscape.
• Become enlightened about drip irrigation
• Hear about attractive, low-water use plants.

Sign up now to reserve your space!

Water Thrifty Landscaping
Where: Stanislaus County Agricultural Center, Harvest Hall, OUTDOORS. 3800 Cornucopia Way, Modesto, CA 95358
When: Tuesday, September 21, 2021
Time: 6:00-7:30 p.m.
Cost: Free
Instructors: Master Gardeners Tim Long and Roxanne Campbell
Questions? Email ucmgstanislaus@ucanr.edu 

Sign up online at http://ucanr.edu/thrifty/2022 or call Misa at (209) 525-6800 to reserve your space.

“Mighty oaks from little acorns grow”
(From old proverb)

I love to stroll under the shade of majestic Valley oak trees in the oak woodland riparian habitat along the Stanislaus River at Caswell State Park in Ripon. I visualize Lakisamni Yokut women (the indigenous people who lived in Stanislaus County area for millennia) as they gathered acorns.

Vital Roles

One of the oldest and widespread trees on Earth, oaks appeared about 65 million years ago, long before humans. Once a common feature of California's landscape, today they inhabit a fraction of their former terrain. Playing a vital role wherever they're found along California's riverbeds, foothills, and valleys, they provide food, water, and shelter for approximately 350 vertebrate species including mammals, birds, amphibians, and reptiles, and can also support over 250 different species of insects and arachnids.

Early humans built their homes, created tools, built shelters and ships from oak wood. Oak galls were used to make dyes, writing ink, and tan leather. Today we use its strong wood to construct furniture, flooring, cabinets, and wine barrels. If you like truffles, thank oak trees, since truffles have a close relation with the roots of oak trees. Truffles are almost impossible to grow. Instead, truffle farmers plant oak trees, hoping to create favorable conditions conducive to the growth of truffles.

California Oaks

Thriving in our hot, dry summers and cool, wet winters, oaks can be found in 52 of California's 58 counties. Of the 600 species found worldwide, there are 20 species of native oak in our state, with three species being the most common in the Central Valley:

• Valley oak (Quercus lobata) – One of California's iconic species, it is the largest oak tree found here, living up to 300 years. The Valley oak grows where there is a water table within reach of the roots, often near creeks and rivers. They grow quickly, reaching 20 feet in 5 years and up to 60 feet in 20 years. A deciduous tree, it's distinguished by deeply lobed shiny green leaves and long, narrow acorns.  
• Interior live oak (Quercus wislizenii) – An evergreen tree, growing up to 25-80 feet tall, it is found in hilly or mountainous areas, near creeks and streams, living up to 200 years. It can produce two types of leaves at the same time, one with a serrated edge and the other with a smooth edge, and produces small, thin acorns.
• Blue oak (Quercus douglasii) – A deciduous tree found in the hot, dry foothills, it grows to be 20-60 feet tall with blue-green leaves which vary in size and shape. With a lifespan of 200-500 years, their acorns are fat and stubby.

Oaks tolerate fire due to their thick, furrowed bark and tough leathery leaves. During wildfires, the larger oaks in areas cleared of fuel may scorch, but rarely burn completely. Damaged trees will resprout from the root crown.

Acorns

Oak trees produce inconspicuous greenish female flowers in the spring and are wind pollinated. Each acorn contains one seed nut enclosed in a tough shell coated in tannic acid which can protect them from fungi and insects. Mature acorns typically drop during September and October. Oaks have unpredictable cycles of boom and bust. Boom times, called “mast years,” occur every 2-5 years with smaller acorn crops in between. Masting takes energy, so oaks grow slower during those years.

An oak tree can produce millions of acorns during its lifetime, but only one in 10,000 acorns grows up to be an oak tree. Acorns are highly nutritious, carbohydrate-rich, and were a diet staple of the Californian indigenous people. Mammals and birds who eat acorns include the Acorn woodpecker, Yellow-billed magpie, California ground squirrel, and Mule deer. However, acorns are toxic to dogs and horses.

The indigenous people called the California scrub jay the “gardener bird” because of its propensity for caching thousands of acorns and not eating all of them, which helped replenish and expand oak forests.

Oak Galls

Have you ever observed “oak apples” in oak trees? Oak galls are created by tiny female Cynipid stingless wasps about the size of a grain of rice. The parasitic wasp inserts its egg into an oak twig, causing a reaction by the tree, a swelling of woody tissue which surrounds and protects the egg, providing shelter and food for the hatching larvae. The larvae eventually eat their way out of the gall, dropping to the ground. Galls come in many sizes, shapes, and colors, which are specific to the wasp and oak species. Some galls are as tiny as sesame seeds and others as large as an apple. The galls do not seem to harm the tree, though oak trees with a lot of galls tend to produce fewer acorns.

A favorite oak gall of mine is “jumping galls,” the size of poppy seeds, round with a dot in the center. Some years large numbers of them drop and litter the ground and sidewalks. The galls “jump” each time the larva moves inside. You can see this in action in this YouTube video: https://www.youtube.com/watch?v=0VI7USm4J5I

Oak Challenges

With their spreading branches casting deep shade, mature oak trees take up a lot of space, so are not ideal for the average residential garden. However, if you have the space and patience for the time it takes to grow, an oak tree makes a stunning garden centerpiece, attracts a variety of wildlife, and requires little care with virtually no water in the summer once established. Oaks may look indestructible, but are sensitive to soil compaction, overwatering, or altered soil levels. It is recommended to limit plantings under an oak since they do not like soil under the canopy to be disturbed.

Today, oak trees face many challenges. Disease, drought, and fire can all destroy oak seedlings. Young oaks are stepped on by grazing animals or run over by machinery. Full grown oaks are often damaged or killed when new homes, roads, stores, or businesses are built. Sudden Oak Death is a disease caused by the pathogen Phytophthora ramorum,discovered in Mill Valley in 1995. Causing a rapid color change from green leaves to brown in infected oaks, it has killed thousands of live oak, black oak, tanoak, and Shreve oak in 14 California counties. Climate change is also putting pressure on oak trees.

To maintain a forest or woodland, each oak tree needs to produce just one replacement tree in its lifetime. You can help regenerate California oak habitat by caring for an acorn seedling and protecting it from harm while it grows into a mighty oak.

All photos by Denise Godbout-Avant unless otherwise noted.