Ask the Snarky Farmer

Each Friday, we delve into the email bag of garden questions:

Doug from Lodi writes, "We have many photinia bushes that we use as a screening plant. This year, several are looking in bad shape. They all get equal water so I feel that's not the problem. Could it be grubs or cut worms in the ground? Are they possibly in need of fertilizer? Our soil in Lodi is fairly sandy, with no rocks or clay.

Doug, it's only fair to the rest of us that anyone with perfect soil must suffer through the occasional plant problem. For a positive identification of the cause of your photinia's illness, you may want to take a sample of an ailing photinia branch to a nursery that employs a CCN Pro or your county's Cooperative Extension office.
If there is spotting on the leaves, and the leaves are falling, it could be entomosporium leaf spot, a fungus that pops up during warm, wet spring weather. Entomosporium is a fungal disease that spots the leaves of plants in the Pomoideae group of the rose family, including apple, flowering crab apple, evergreen pear, hawthorn, pear, photinia, pyracantha, quince, Rhaphiolepis (pictured), and toyon. If that is the case, remove infected leaves from the ground and the shrub. Also, avoid overhead watering. Making sure there is room between the plants for good air circulation can help. If that is impractical, try removing some of the lower branches.
And, in a rare instance where mulch can be counterproductive, the experts at UC say to remove any mulch beneath the plant, which may harbor the fungus.

p.s. "CCN Pro" stands for "California Certified Nursery Professional"... not to be confused with John Fogerty, a CCR Pro.

Robert of North Sacramento wants to know: "I am getting ready to put in a garden and the soil gets pretty hard, possibly due to clay, and I was considering tilling in some ground bark to help loosen the soil. I have access to two types: cedar and fir. Which would be best? Is there something other than bark I should be looking at?"

You may want to check with Doug, maybe he has a spare hundred cubic yards of pristine topsoil that he might be willing to share. If that doesn't work out, try adding organic compost instead of bark into your clay soil to improve it. Bark takes quite awhile to break down when mixed into soil. Plus, it will tie up nitrogen that your existing plants need. Instead, add about one cubic yard of organic compost for every 300 square feet of garden area. Use the bark, either cedar or fir, as a four inch layer of mulch around your trees and shrubs or on top of your garden bed. This will help control weeds, conserve soil moisture and slowly feed the soil as the bark decomposes. The question you have to ask yourself: do I rototill the compost into the soil, or just let it rest on top of the existing soil? There are two very vehement schools of thought on this...a subject for a future blog!

And if your backyard looks like this, cracked clay in the summer, mud in the rainy winter...add four inches of mulch on all your walkways. It will improve the soil and keep you from sinking to your knees in the winter.

Maureen of Paradise wonders, "I'm baffled. What is 'hardening off'?"

"Hardening off" is one of those 50-cent horticultural terms that gardeners like to use to make them feel smarter than everyone else. Sort of like "acarpous" (sterile), "bipinnately compound" (a complicated leaf construction, e.g., the shape of a Chinese pistache leaf) or "File for Chapter 11" (what some nurseries do in a recession). "Hardening Off" simply means: let the plant get used to the outdoors slowly. It has nothing to do with Viagra. For example, if you have tomato seedlings indoors in early spring, you may want to place them outdoors in a shady spot for daytime hours for a week or so in mid-spring (bring them in at night). During the second week, let them spend the night outdoors, too, in a protected area (as long as no freezes are predicted). Then, during the third week, acclimate the plants to their permanent home. Plant them in their garden home, but place a row cover or hot cap or wall o' water around them for a couple of days. Then, let 'em grow!