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Saturday, August 20, 2016

Don't Wrap Saguaro in the Winter

Q. For several years my saguaro has been turning brown slowly but the process has speeded up this year.  I have two others, one of which I had to transplant after it grew too much for its original location, but neither of them has problems and seem to be completely healthy.  I really don’t believe I am overwatering it, but it is a possibility

Q. The last time I have seen this kind of browning on the surface of a saguaro is in a landscape where they were wrapping the Saguaro each winter in an attempt to protect it from winter cold damage. They used burlap.
            It caused a lot of surface disease problems on the cactus because of a lack of air circulation. They finally stopped doing that but the damage was already done and the surface of the cactus had a lot of brown damaged areas.
            I hope you are not doing that. If you are, stop it. Let it breathe and take your chances. I know they are expensive but wrapping them causes more damage than good.
            Make sure that water is applied to the surface of the soil surrounding out to a distance of six or 8 feet. Do not water too often. Water deeply in these areas about every 2 to 3 weeks. I would rather see it at three weeks than two weeks and actually three weeks is really too often.
            These plants store water in their fat bodies and can live on this water for a long time. When water is present they absorb it like a sponge, very quickly and that fat body swells up and expands like an accordion. That's why it's ribbed. Don't wrap it in the winter time and water it deeply and not very often.

Sudden Exposure to Full Sun May Burn Star Jasmine

Q. My next door neighbor cut down large pine trees that shaded my wall of star jasmine 2 days ago. Is there even any point in trying to rig a shade cloth to get through the rest of the summer in hopes that they can "harden off" and transition to full sun through the winter and spring next year or should I basically pronounce them dead and start the grieving process now?

Star jasmine on a wall
A. Star jasmine can handle full sun if it’s planted in good soil. But you are right, it will probably go through some shock to have it exposed to the hot sun at this time of year. I am guessing you will have some scorching of the leaves and some dieback. But I think it will rebound. You may have to cut the damaged parts back, fertilize it in October and let it regrow in the spring.
Star jasmine failing and yellowing because it's growing in poor desert soil with the surface covered in rock mulch
            At this point, I would wait and see what happens. Plant health has a lot to do with how plants handle hot weather. Plants that are not as healthy will have more difficulty during hot weather than plants which are in good health. In a contrast to this, plants that are not as healthy can grow in protected environments and still look good.
            I would encourage you to buy some decent compost and spread about an inch layer at the base of these plants and water it in. The best compost for this is at Viragrow in North Las Vegas. You can buy it by the bag for I think about $2.50 a cubic foot.
            Soil improvement will go a long way in improving plant health and their ability to withstand adverse conditions. Because of the high light intensity and warmer temperatures, they might begin to use more water in this location.
            I don't necessarily think you need to apply water daily in this spot but you may have to increase the volume of water 20 or so percent and maybe add an extra day of watering each week now. Try adding this water with a hose first but avoid daily watering If you can. Watering daily might create some problems for these plants if the soil doesn't drain very well.
            If there is no surface mulch under these plants then I would put some there. Wood mulch is better than rock mulch for soil improvement. Use a 2 to 4 inch layer. You can get it free from the University Orchard in North Las Vegas which is 100 yards east of the corner of horse drive and North Decatur and Aliante Any Tuesday, Thursday or Saturday morning.

Butterfly Bush Doing Poorly May Be Grubs in the Soil

Q. I have a butterfly bush that is struggling. It looked wonderful this past spring, now the leaves and blooms are alot smaller. There are alot of leaves turning black. The bush has full sun and 
gets watered regularly. Do you know what the problem might be?

This is from a previous question regarding the same problem on Lantana. She is pointing to grubs in the soil eating the roots and damaging the plant.
A. Check for grubs (worms) eating the roots. This is a common problem on butterfly bush this time of year. Use a liquid insecticide as a soil drench to wash the roots and kill the grubs. You can also use granular insecticides and lightly watered into the soil at the base of the plant. Look for one that is for grubs at your nursery or garden center.

Plant Replacements in the Fall or Spring

Q. I removed two Italian Cypress trees (harder project than I imagined, especially the stumps). When is a good time to replace them, how big of a hole should I dig, and how should I prepare it? 

A. I can imagine that was a very difficult job removing Italian cypress. Probably the easiest way to do it, yes I know it's already done, is to cut it off and rent a stump grinder and grind out the stumps. The wood grinding's mixed with soil makes a fabulous mulch.
            The best time to replant is in the fall months but the problem is plant selection. There is usually not much to pick from. The best stuff is gone and the nurseries don't want to be stuck with anything through the winter and availability of plants from wholesalers is limited to stuff that didn't sell. But you can still find things if you're willing to look around.
            An alternative to Italian cypress is the Skyrocket Juniper. It is hard to find but stays narrow and smaller. They used to be popular 30 or 40 years ago. This is not a desert adapted tree so it will require soil improvement and I would mulch it with wood mulch at the base on top of the soil. I have never seen it planted in our hot desert climate but I don't see a reason it won't work with some soil preparation, decent irrigation and wood mulch.

You should not have a problem planting in the same holes if the Italian cypress he removed was healthy.
            Dig a hole 3 to 4 times the diameter of the container that the plant comes in. If these holes already have quite a bit of organic matter in them... You can tell by the color... Then don't add
anything. But otherwise mix the soil you take from the hole 50/50 with compost. The best compost out there locally for doing this is Viragrow compost in North Las Vegas.
Viragrow compost available in North Las Vegas