‘Candia Meidland’ shrub rose
“I have five rose bushes that I planted approximately seven years ago. The soil is hard clay and, before planting, I dug out holes 2 inches deep and 2 inches wide for each rose bush. I used a mixture of amendment and fresh soil for roses in each hole.
The plants blossomed beautifully until this year. The roses don’t look healthy and happy and I’m wondering if the soil needs an additive. I have regularly used plant food for roses, but now I’m thinking that the soil may need some nutrients. Is there a soil additive I can use without checking the pH levels?”
Rich Salvato, Oak Park
I know how difficult the soil in Oak Park can be.
Digging large holes and filling them with good soil prior to planting was a wise decision. Now that seven years have passed, however, perhaps the roots of your roses have grown beyond their comfort zone and now have reached the intractable native soil.
Then again, even under the best circumstances, many roses, especially hybrid teas, tend to go into decline after they have been in the ground for seven years or so. Coupled with the fact that your roses are growing in hard clay, it sounds like they have done well enough.
Some people swear by Epsom salts, available at any drug store, as a rose booster at every stage of growth. You can soak bare root roses in it, using 1/2 cup of Epsom salts per gallon of water. You can also mix a tablespoon of Epsom salts into the soil when planting a rose bush.
At the end of winter dormancy, a rose bush benefits from 1/2 cup of Epsom salts gently mixed into the upper inch or two of soil at its base.
Finally, a solution of Epsom salts (1 tablespoon per gallon of water) may be sprayed for pest control. This same spray, incidentally, applied to the flowers of tomatoes and peppers, increases fruit production.
Epsom salts is the trade name for magnesium sulfate. Magnesium is an element that is essential to the manufacture of chlorophyll. Sulfate is especially useful in Southern California soil, which is on the alkaline side of the pH scale, since it has an acidifying effect.
Roses appreciate a soil pH between 5.8 and 6.3 even as our local soil typically registers a pH between 7 and 8 or higher. Gypsum, another sulfur-containing product, also will lower soil pH.
The reason roses require a somewhat acidic soil pH is to absorb micro-nutrients such as iron, zinc, magnesium and copper that are simply unavailable in alkaline soil. Here, foliar fertilization with a product that contains these elements can be useful.
Some gardeners use liquid kelp/seaweed because of its mineral content. You should also cover the soil with 2 or 3 inches of compost or mulch to keep the roots of your roses cool. Just keep mulch off rose canes or fungus problems could develop.
Avocado troubles
“About eight months ago, we planted a 6-foot avocado tree in our patio. The tree went into shock and lost most of its leaves. It pulled through, however, and was growing and filling out very nicely.
“Then, the heat wave hit us. Since then, the tree, which is in mostly direct sunlight, seems to be burning up. Many of the upper branches are turning black and the tree is losing some of its upper leaves again. My wife once heard that painting avocado branches protects them from the hot rays of the sun. Do you have any suggestions that can help us save our beautiful tree?”
>Cliff Secia, Tarzana
The greatest challenge presented by plants that have defoliated in hot weather is resisting the temptation to water them.
You intuitively think that a plant wilts or loses its leaves in summer as a result of insufficient watering. Usually this is the case. But wilting can also be a consequence of over-watering and waterlogged roots.
Regardless of why a plant wilts, once it has done so, the soil should be kept minimally moist until new growth is observed.
Trunks of young trees are often painted white (50 percent latex paint, 50 percent water) to reflect harsh sunlight that could burn and crack the wood. The bud union of grafted trees is especially sensitive to sunburn.
I would not be concerned with painting the upper branches but focus instead on being gentle with your watering until the tree returns to its former vigor.
Tip of the week
Epsom salts are useful in promoting the growth of plants other than roses, too.
Houseplants benefit from a monthly treatment of Epsom salts, applied at the rate of 2 tablespoons per gallon of water.
Tomatoes prosper when fed every two weeks with 1 tablespoon of Epsom salts per foot of plant height.
Evergreen shrubs and azaleas respond favorably to an application every two to four weeks of 1 tablespoon of Epsom salts per 9 square feet of growing area.
Lawns enjoy 3 pounds of Epsom salts per 1,250 feet each spring, and trees appreciate three annual applications of two tablespoons per 9 square feet of root zone, the area directly under a tree’s canopy.
As a general rule, 1 cup of Epsom salts may be mixed into any soil prior to planting. The only reservation regarding Epsom salts concerns herbal sage (Salvia officinalis), which reacts unfavorably to its application.
(The above information was supplied by the Epsom Salts Industry Council.)
