Sonoma County Garden Doctors tackle water sprouts, root flares, pests and more

Mario asks: What is the difference between suckers and water sprouts on trees? I was told it is important to remove them on my mature plum tree.

Water sprouts are the vertical and vigorous upright branches that will grow quickly throughout the canopy of the tree. When there is an abundance of water sprouts they will overcome the other limbs and branches thus prevent light from penetrating the overly thick canopy and generally will weaken the tree.

Suckers are those numerous new twigs/branches that appear at the base of the tree or shrub. Ones around the base of the main trunk are referred to as crown suckers. Those upright ones growing farther out from the trunk and the underground root system are also suckers. All will weaken the tree by using up available nutrients. Some trees and shrubs are more susceptible to forming suckers. Ornamental purple plums and crabapples fall into this category and should be cut back to their base as soon as they appear. Water sprouts throughout the canopy will continue to form so repeated removal is important to keep them in check.

Roses will form suckers off of vigorous rootstocks. Suddenly to the untrained eye a new tall spindly cane will seemingly put on several feet of growth and develop blooms of an entirely different color. Eventually the suckers will take over and kill the original grafted rose. The vigorous rootstock is called “Dr. Huey” with blooms of a red burgundy color. Roses propagated from cuttings will not form suckers. Rose suckers should be removed from beneath the soil line by pulling or cutting them back. They may continue to form new suckers so be diligent in your pruning tasks.

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Olivia asks: How does one identify the root flare when planting “containerized” and bare root shrubs?

The root flare is identified as the bulge at the base of the tree or shrub that is above the spreading root system. By pulling the soil away from base of the main trunk or stem of the container plants the bulge is visible. Do not plant a tree or shrub lower than the root flare. If one plants a tree or shrub below the root flare rot can potentially set in.

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Mike asks: How do I bring an overgrown shrub back to a more desirable shape and size? Over the years, my Abelia “Edward Goucher” is no longer as attractive as it once was. My late parents gave it to me as a Christmas gift for our new landscape.

The least drastic way to rejuvenate your Abelia is to remove 1/3 of the old stems/branches each year. Also, remove all dead branches to open up the shrub to more light and air.

This does not mean shearing as in hedging with loppers, but taking into consideration its original natural structure that is loosely open and cascading. The process may also require some minor pinching or tipping of branches during the growing season. Be patient, Abelia can be rejuvenated easily.

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Louie asks: Will deer eat ferns? We have moved to a new home that has plenty of shade and also a plethora of visiting deer. I thought an addition of ferns would be a great textural balance.

Of all the plants that deer eat and try in my own garden, they have not demolished my ferns. Mine are a variety of sword ferns (Polystichum munitum), autumn ferns (Dryopteris erythrosora), and painted ferns (Athryium niponicum), all evergreen and all thrive in our area.

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Edward asks: Any ideas on how to discourage and keep birds away from our raised strawberry bed?

Try anchoring numerous bendable PVC hoops or heavier wire above the beds. Roll a fine mesh on top of the hoops and anchor it with clips or clothespins. Roll the mesh back when harvesting the fruit. This is also effective for lettuce beds. Be creative and use a method that will work best for you.

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Mabel asks: How do I know if a tree or a shrub is a true weeping variety when they are purchased as a small sized specimen?

The label will describe them as weeping or more importantly as “Pendula” on the botanical label. Lastly, look up the name of the tree and its natural growth habit, it will describe it as “Pendula” or not.

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Ana asks: Is there an ornamental grass that will thrive in shade?

Yes, Hakonechloa macra “Aureola” is a variegated form of Japanese forest grass. Lovely, as it brightens up shady areas but does die back during the cold winter months. It is also a fine container plant that does well when grown in morning eastern sun exposures.

Dana Lozano and Gwen Kilchherr are garden consultants. Send your gardening questions to The Garden Doctors, at pdgardendoctor@gmail.com. The Garden Doctors can answer questions only through their column, which appears twice a month in the newspaper and online at pressdemocrat.com.