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Old 06-23-2002, 03:27 AM
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Default arctostaphylus uva-ursi woods compact

I am a horticulturist who just moved to california from N. Arizona we had manzanita growing native. I would like to ask if you have some similar problems with the survival rates here in California. We lost anywhere from 50-70% of manzanitas planted within a one year span. I am concerned about planting this spp. at a location in Menlo Park. I dont want to loose the plants we plant. Has anyone had similar survival rates here in Ca? or does anyone have a suggestion on how to improve the survival rate?

thank you,Heidi</p>
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Old 06-27-2002, 05:39 AM
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Default Re: arctostaphylus uva-ursi woods compact

Heidi -

I worked at a native plant nursery for 7.5 years, and heard lots of manzanita stories from customers.

First, Arctostaphylos species in the wild tend to grow on nutrient-poor, well-drained, often acidic sites. Even Arctostaphylos species native to San Mateo County will be growing up in the hills on soils very different than the soils found in Menlo Park. For example, the tall, beautiful Arcto. montarensis is found on the top of Montara Mountain growing on decomposed granite. Manzanitas are really niche adapters, growing where plant pathogens will not thrive. They can also be poor competitors.

One of the best things you can do is to create a well-drained place for manzanitas to grow. They don't do well with organic matter that holds moisture and provides a hospitable environment for diseases. You can improve the texture of the soil with lava sand or expanded shale from American Soil products in Berkeley. These are neutural gravels that incorporate air. However, it is very hard to do anything about the PH factor. If soil is too alkaline, manzanitas probably won't grow. The trouble with adding crushed, decomposed granite is its tendency to mesh together and form a pavement-like surface that excludes air. You might alleviate this tendency a bit by straining out the fine particles before mixing with your soil.

Next, manzanitas seem to do best if mulched with gravel, rather than organic mulches. Bark and other organic mulch materials can add nitrogen to the soil, which won't do the manzanitas any good. They also provide breeding spaces for pathogens, as they retain water. Gravel, on the other hand, provides drainage and helps keep the crown of the plant dry.

If one is going to grow tempermental plants, it is best to do it right and make all the necessary preparations. Even relatively easy to grow Arctos. like A. densiflora 'Howard McMinn' or A. uva-ursi 'Emerald Carpet' must have their requirements met to insure long-term survival.

Another mistake people in the landscape trade make with manzanitas is pruning. Cutting into the plants exposes inner tissues to airborne pathogens. Therefore, pruning should be avoided, if possible. I've seen cases where maintenance crews tried to turn 'Howard McMinn' into hedges or little dumpling bushes. The plants did OK for a few years and then declined.

Finally, there is watering. Arctostaphylos should be planted out in the fall, so the rain can provide irrigation. In the Bay Area, I would consider once-a-week watering during the plant's first summer to be too frequent. Twice a month is better. In your own garden, where you can keep an eye on things, you might get away with even less watering. The goal, after all, is for the plant to be pretty much on its own, just like a wild plant. Overhead irrigation is not good, and should be avoided, as manzanitas are subject to many pathogens that can attack leaves and twigs.

Hope this helps,

Lori Hubbart</p>
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