What Your Soil Can Do For You

California native Penstemon heterophyllus thrive in low wate-use gardens.

“The soil is made of butterfly wings, dinosaur teeth, pumpkin seeds, lizard skins and fallen leaves.
Put your hands in the soil and touch yesterday and all that will be left of tomorrow shall return
so that new life can celebrate this day.” Betty Peck

We are all familiar with the saying, “feed the soil, not the plant.” This is because plants do not grow independently. They grow in a partnership with micro and macro organisms including fungi, beneficial bacteria, micro arthropods, nematodes, insects and worms. We are just beginning to understand the complexity of soil biology. Soil is the foundation of agriculture including home gardening. When you maintain healthy soil, healthy plants will follow.

The biggest issue we gardeners face is the ongoing battle with soil. If yours is difficult to manage or unproductive you’ll be disappointed with the performance of many of the plants you put in the ground. Even tough plants like California natives have soil preferences and they are not always what’s in your garden.

We live on ancient sea cliffs. Soils in Bonny Doon and Scotts Valley consist of shallow, excessively drained weathered sandstone and shale. Felton soils were formed from shale, sandstone or mica schist. Those in Ben Lomond and Boulder Creek had their beginnings from weathered sandstone or granite. Although these provide the necessary mineral component of our soil, organic matter or humus from decayed plant and animal material are necessary for fertility.

Here’s why improving your soil will make a difference to the health of your plants.

Good soil-with both organic matter and minerals-helps plants grow by forming the food supply for soil bacteria that help make food available for plant growth. Most of a plants energy goes to producing substances that drip out through the roots to attract bacteria and fungi. These in turn attract good nematodes and protozoa to the root zone. The protozoa eat bacteria and the nematodes eat not only the bacteria but also fungi and other nematodes to get carbon. What they don’t need they expel and this feeds the roots much like earthworm castings.

Down in the soil, if a plant needs different foods it can change what is secretes. Different substances will attract different bacteria, fungi, nematodes and protozoa. This huge diversity of soil biota helps the good guys keep the bad guys in check.

A common way to destroy the microbiology of the soil is to add salts in the form or non-organic fertilizers. The salts kill the bacteria and fungi by dehydrating them. Then the plant can’t feed itself and becomes dependent on its fertilizer fix. Without the good bacteria and fungi in the soil other parts of the food chain start dying off as well.

The soil food web is also responsible for soil structure. Bacteria create slime that glue soil particles together. Fungi weave threads to create larger soil particles. Worms and insects distribute bacteria and fungal spores throughout the soil and create pathways for air and water.

What can you do to bring your soil back to life?
• Mulch around perennials, shrubs and trees with1/4“ of compost and 2-3” wood chips or other organic mulch.
• • Apply mycorrhizal fungi, especially in a new garden that’s been rototilled or chemically fertilized. You can find this in most organic fertilizers and some organic potting soils.
• Use aerated compost tea
• Try to avoid walking on the root zone of plants. This kills fungi in the soil. Install stepping stones to preserve soil structure.

Dogwoods in the Garden

Cherokee Chief, like all dogwoods, attract a variety of wildlife

I don’t know if I like the pink ones or the white ones best. A flowering dogwood in any shade is stunning. My friend Colly, the food columnist for the Press Banner, has several dogwoods in her garden, including a Cherokee Brave with dark pink flowers. They are so beautiful at this time of year and in the fall when they turn bight red.

There are four main species of dogwood trees. From the Himalayas in China comes cornus capitata. Korea is home to cornus kousa. Cornus florida is native to the east coast and the west coast is home to cornus nuttallii or the Western dogwood.

I see so many showy varieties available now. The fast growing Venus Dogwood is a hybrid of the Pacific dogwood (Corpus nutallii) and the Korean dogwood (Cornus Sousa). It has exceptionally large white flower bracts. Good disease and drought tolerance make it a good choice for the garden. The Constellation dogwood is a similar hybrid to the Venus but sterile so it doesn’t get the red fruits that the Venus produces. Perfect for the small garden.

The fast growing Stellar Pink dogwood is a cross between cornus florida and cornus kousa. With profuse, large, overlapping blush pink flower-like bracts it’s a magnificent landscape tree for small gardens that produces no fruit.

Our native Western dogwood is unfortunately prone to leaf spot fungal diseases when grown out of their range. They are a little temperamental in the garden before they reach the age of 10 years but after that they tolerate seasonal flooding and flower and grow with little care in morning sun or light shade. They prefer moist soil.

We are all familiar with the Eastern dogwood (cornus florida) that’s blooming now. With various shades of pink, red or white blossoms they are stunning. Take note that their root system is prone to disease if not grown with good drainage. An awesome variety ‘Pringlei’ or Mexican Flowering Dogwood is grown by a fellow gardener and it’s a stunner. With its unusual flowers than look like Chinese lanterns to the red fall color this is a species to be on the look out for.

The Wedding Cake Tree (cornus controversa ‘Variegate’ ) is another unique variety. When this small dogwood blooms the large flowers cover the tree like snow. The tiered horizontal branches resemble a wedding cake when in bloom.

Deciduous dogwoods don’t like wet feet especially in the winter. That’s how they develop fungal disease. But there’s an evergreen dogwood that can handle moisture all year round. Cornus capitata Mountain Moon is a tough tree that can handle strong winds and isn’t bothered by any pests or diseases. They enjoy lots of organic matter as do all dogwoods. Huge flowers up to 6” wide can last from late spring into early summer. After flowering, the fruits begin to form and grow into red balls about the size of large strawberries. This is the reason is it also known as the Himalayan Strawberry Tree.

Dogwoods attract a variety of wildlife. All sorts of critters use this tree for food and shelter. The giant silk moth and several species of butterflies favor dogwoods as host plants. The spring flowers provide nectar to bees and other pollinating insects. Robin and sparrow are just two of the bird species than build nests on the horizontal branches and many others seek shelter in the leaves. The high calcium, high fat, fleshy red fruits are eaten by 35 species of birds including titmice, juncos and waxwings.

Many people think of dogwoods as an understory tree but this location is often too shady. Grow them in a full or partial sun location that gets afternoon shade after 4:00 PM. Add a couple of extra drip emitters or inline drip tubing to your irrigation system and they’ll be happy.

Dogwood are a good tree choice for the allergy sufferer as their pollen is not wind borne. Their showy flowers, which are actually bracts, are pollinated by insects. Their pollen is large and heavy, sticking to insects rather than becoming airborne and leading to sneezing, runny noses and watery eyes.

How to Live with a Wisteria

Fragrant wisteria attract hummingbirds and bees.

Wisteria are one of those vines that you either long for or lament ever having planted. They are all fragrant with a delicious sweet scent that varies from faint to strong to almost overpowering. Bees and hummingbirds love them. Here are some tips to choose and enjoy one in your garden.

Wisteria are one of nature’s most resilient survivors. They are able to withstand and recover quickly from difficult conditions. To some they are a little too tough for their own good with a growth rate rivaling bamboo during the summer. If you dream of a wisteria-covered pergola shading your patio here are some maintenance tips that are sure to keep both gardener and vine happy.

Wisteria are so vigorous they can be pruned at any time, keeping them in bounds and clearing out unwanted or dead growth. Prune out any stems you see extending into eaves, windows or shingles. If yours has gotten away from you, you can even prune it down to the ground and start over with training although you’ll have to wait a few years for your vine to bloom again.

To control their size major pruning is done during the dormant season. Start by trimming the long tendrils that grew over the summer back to about 6 inches from the main trunk. Cutting the tendrils back in this way will initiate flower bud development, neaten the plant up, and show off the attractive trusty, gnarly character of the vines.

Whatever time you do renovation pruning remember the response of the wisteria to aggressive pruning is to literally explode with new runners. They put energy into new vegetative growth at the expense of flowering. Make sure you keep up on ongoing maintenance pruning by removing all unwanted runners right to their point of origin. Then prune back the others to 3 buds or sets of leaves. Repeated pruning of these runners is what will eventually give you spurs of wood, short laterals that in turn will provide you with flower clusters. You need to prune these runners all season long which ends up being every 3-4 weeks.

Do not fertilize your wisteria. They do not flower well if there is an over abundance of luxuriant growth. Over feeding also ends up giving them the means to become un unmanageable monster. If you have trouble getting your vine to flower an application of a high phosphorus fertilizer may promote blooming.

Maintaining a wisteria requires some diligence but the reward is worth the effort. Remember this especially during winter pruning season to make summer maintenance easier. If you find that the wisteria vine has invaded a nearby bed, cut roots with a shovel below the soil line to control any that have wandered.

Which variety of wisteria should you get to cover your arbor, pergola, tree or other structure?

Chinese varieties such at ‘Cooke’s Special’ have clusters of fragrant blue-purple flowers 20 inches long. This variety can re-bloom which makes it a favorite. Chinese wisteria can take up to 20 years to mature enough to produce flowers, but once it has matured, the plant is very long lived and can live up to 100 years.

Japanese wisteria like ‘Caroline’ bloom early with mauve flowers. ‘Royal Purple’ , known also as ‘Black Dragon’ , has sweetly scented dark purple flowers. Japanese wisteria are most effective when grown on pergolas so their long flower cluster can hang freely.

American wisteria, native to more eastern areas of the U.S. is a smaller, less invasive species that grows about a third the rate of Asian wisteria. ‘Amethyst Falls’ blooms at an early age with lightly fragrant purple racemes. Use in containers for porch or patio, train up an arbor or trellis or as a small free-standing tree.

Silky varieties produce a profusion of short, 6 inch, fat clusters of strongly scented flowers that open all at once. They have velvety seed pods and bloom best in full sun.

All parts of the wisteria vine contain a toxin known as wisteria which can cause stomach upset. Growers should also be wary of pets and children eating the flowers or seed pods.

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