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SHARING SECRETS: Keeping Shrubs and Mature Trees Healthy

Edited by Dayle Cheever.

With the on-going drought and water restrictions, what are you doing to keep your shrubs and mature trees healthy? Have you noticed any significant changes to your mature shrubs and trees?

Charlotte Getz: We are still watering everything in the yard, on a two-time per week basis, unless it rains and we turn off the irrigation. Trees and shrubs are still doing well because I have mulched them all with a two- to three-inch layer of compost. The compost retains the moisture around the plants and retards weed growth.

Candace Kohl: I have changed some of my watering to drip emitters for all areas, but I am cutting back water on the grass and flowers, more than the trees and shrubs. Also, I have called in a professional for advice on my many Torrey pine trees. Some of them do look a bit under stress, but most are fine. (92014)

Gabrielle Ivany: Last year’s lack of rain and hot summer, combined with the watering restrictions, certainly affected my trees. Some of the branches on my big olive tree died back last year. I hand water more. I diverted some of the water from a close-by downspout to the olive tree via a French drain. That seems to have helped this tree. However, I could not save my young peach tree, in a different location, even though it, too, was hand watered more. I am thinking of getting rain barrels. (92128)

Susan M. Oddo: Heat is the main enemy, and with a variety of 20- to 30-year old trees, tall Callistemon and other shrubs, the shade canopy helps hold in moisture. This year we are adding mulch over much of the property and reducing water consumption by about another 20 percent (already cut back 35 percent). We find that reducing weekly surface irrigation to trees and giving them a deep, slow drink once every two weeks has actually made them healthier and uses less water. We will also have the two 80-foot Torrey pines laced, which reduces the amount of water the trees need. We will do the same with the coast live oaks, which have germinated naturally on the lower half of the property. They receive enough water to, hopefully, keep them healthy enough to resist the new fungus and beetle invasion.

Pat Welsh: The changes in my plants this year are quite the opposite of what one would expect. Everything has grown more rapidly than usual and flowered more profusely. Faster rate of growth of Chinese wisteria, Lady Banks rose, bougainvillea, Victorian box (Pittosporum undulatum), and Geraldton waxflower (Chamelaucium unicatum) has been particularly noticeable. I think all of this might be due to the greenhouse effect, since plants inhale carbon dioxide. Greater amounts of carbon dioxide in the atmosphere theoretically should mean that, through photosynthesis, plants can create greater amounts of sugar, which they need for growth. (The jury is still out on this with the scientific community since tests have resulted in conflicting evidence.) However, I noticed the same thing happened with plants all over Del Mar after the backcountry fires caused thick smoke to blanket our town for a couple of months. A few months later every flowering tree, shrub, or vine bloomed its head off and many plants, including Monterey cypress, put on more growth than usual.

Kristie Hildebrandt: We live in Escondido in a hilly, rural area and have 67 hedge plants surrounding our backyard for privacy. Nine of them are Carolina Laurel Cherry and were planted in a retaining wall 1-1/2 years ago. The rest are Ficus nitida; 22 of the F. nitida were planted about five years ago and the rest were planted about two years ago. All are on drip. About one year ago I had some guys come to trim everything and they noticed that in the tops, I had thrips and gall wasps on the F. nitida and had some other chewers on the laurels (most are 18 feet tall now). Up to that time, I had never had any problems but I think reducing the water added some stress, which caused the insects to move in. I read that gull wasps were not harmful but would disfigure the hedges and cause leaf drop. I also read that the thrips could kill my F. nitida. The chewers on the laurels were beginning to wreak havoc. Big investment here with 67 of them and I did not want to lose any. I engaged an agricultural pest control company that was recommended by Grangetto’s. They’ve injected each hedge plant twice in the last year, which included fertilizer (every six months). All are doing well now. Still prior gall wasp damage, but nothing new, no thrips and no chewers. Everything has been thriving but I have been trying to keep a close eye out, even in the tippy-tops, to make sure all stays well.

Sue Ann Scheck: Pruning shrubs and trees in the right season! Deep watering when necessary, also removing mature plant material when it is entirely spent to make room for healthy, living specimens. Some of our shrubs are 25 years old.

Jackie: My peach tree has much less fruit than usual this year despite an abundance of green leaves and my 25+ year old Magnolia grandiflora is losing lots more leaves than usual for this time of year, though still producing many flowers and new leaves.

Walter Andersen: I moved recently, so with the re-landscaping we chose more low water use plants, including leptospermum, puya, cistus, kalanchoe, aeonium, cycads, and Acacia cognata ‘Cousin Itt’ (spectacular plant). Lots of bark mulch covering the soil and a DIG watering system. In a very private, shady area I have my Platycerium (staghorn fern) collection (also on a DIG system) with some ferns and bromeliads in the ground. We replaced old gravel areas with concrete pavers and the horrible looking lawn is now artificial turf. A new supplemental planting of Acacia redolens helps the ice plant hold the steep bank in the back. Calliandra surinamensis was planted near the bottom of the bank to add height and blooms.

Tom Biggart: The whole scenario is pretty hopeless! We have lost a huge Araucaria and a mature Banksia integrifolia. As the mature trees and shrubs die we replace them with tougher plants or…. Plant Oxalis!!

Paula Suttle: I slow water mature trees by putting the hose at the base, at a very low trickle and leave it for a day or two. I have been gathering fallen debris from other parts of the garden to spread on open areas that attract unwanted weeds. I am letting attractive wildflowers that volunteer remain where they grow. I have tried four or five native grasses, but only one did well and spread (I forget which one). I stick to natives when I plant shop. I don’t trim overhanging plants as much so that I don’t cut down on shade. I place water-loving (more water needy plants) near faucets.

Jessica Colton: I have a mature Palo Verde in my front yard. I estimate she is probably 50-60 years old. This old girl was looking pretty bad this year and although she doesn’t drink very much water, I just assumed the drought was part of the problem. With her age she has lost a lot of her green and is brown so I didn’t pay much attention to her condition until one day my neighbor left a note exclaiming that she had never seen my beautiful tree look so terrible. That scared me… and after a much closer look at the dead leaves I realized I had an emergency on my hands. So I called a pest service and found out it wasn’t the drought, she had tree mites in a bad way. I had to have two treatments done on her, but now she is full of leaves and happy again. My magnolia, on the other hand is more affected by the drought and I have been watering on my designated days, or once a week. I’m looking forward to hearing what other are doing.

Tina Ivany: I had a rain barrel installed last October, a 205-gallon Bushman tank. It filled up several times from the rain we got. I used the water to deeply irrigate some of my bushes and trees, with the trees getting first dibs. My goal was to store the water in the ground as opposed to the tank. The plants loved the water and grew quite a bit. I know they had been stressed and it was fun to watch all that lovely water soak in, guilt free. The leaves on my camellias have never been so glossy!

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