Large Boxed Tree Needs Extra Help

Q. Should a newly planted 36" boxed purple robe black locust tree have it's nursery stake removed? I sent you a picture of it.

Readers Purple Robe Black Locust staked.

A. Larger trees need their roots stabilized for one to two growing seasons and then the stakes removed. In your case the tree has poor trunk strength since the trunk has no taper to it and the trunk will snap in high winds.

            Immobilize the roots by re-staking the tree. Let side branches develop along the trunk to improve trunk taper and strengthen it. Normally, a tree with good trunk taper can have its stakes removed after one to two growing seasons. A tree with poor trunk taper will require a longer period of staking to strengthen the trunk AND give it solid rooting into the surrounding soil.

            Allowing side branches to grow along the trunk helps promote taper in the trunk reducing its need for staking after one season.

            Ideally, the tree should have small stems growing from the trunk covered in leaves, removing them only when they reach about pencil diameter. This increases stem taper, reduces the possibility of shear or snapping in high winds. 

            Trees also need to “sway” in the wind. This swaying or movement of the trunk from side to side also helps to develop taper in the trunk. But the roots of the tree need to hold the trunk in place at the bottom.

            This tree will need to be staked for awhile to keep the trunk from snapping. Probably at least one season. I would probably restake the tree with either two or three stakes to support the trunk and keep it from bending to the point where it could snap and immobilize the roots.

Large trees usually need stakes to support the trunk. The stakes should be driven deep enough so that they are in solid soil. The support from the stakes should be low enough to allow the top of the tree to move but keep the rootball from moving.

            Two methods used for re-staking include a two to three stake method with the stakes driven into the solid soil beneath the rootball. The other way is to use guy wires to stabilize the tree. I supplied pictures that I will also post on my blog.

            This next year let small branches grow from the trunk if they develop. These will increase the strength of the trunk and help reduce sun damage to it as well. Remove older branches from the trunk when they get larger than a pencil in diameter. Cut them off flush with the trunk. Do not use pruning paint.

Container Plants Difficult to Manage for Snowbirds

Q. We winter in Boulder City in a condo RV park. Three years ago we planted a rose bush that did wonderfully well until it died last summer. The pot gets plenty of water from a drip hose. We would like to put something in the pot more capable of surviving the extremes of the high desert. I would be happy with anything that will flower or fruit when we are here in the winter and is OK with being abandoned for six months. 

A. It will be very, very difficult to grow much of anything in a pot if it is not attended to. You might be better off putting something there that will not die and, while you are here, growing something that you can dispose of when you leave such as an annual.

            The other possibility is to have someone care for your plants while you are gone. The summers here are brutal on plants as you know. We get fluctuations in our weather that are very unpredictable.

            If you insist on growing something in a container then double pot your container so that the container you are growing in is surrounded by another container or object that shades the outside of the inner container.

            Surface temperatures of containers that receive direct sunlight in late spring and summer will produce temperatures inside the container that will kill plant roots. Double potting a container with a larger container with gravel in the bottom and just airspace on the sides will help insulate the soil inside the container.

            Surface temperatures of a container will easily rise above 165F in direct sunlight. This heat transfers to the soil and cooks the roots on the side exposed.

            Another possibility will be to grow cacti in containers and watering it no more than about once every two weeks. Once a week if the container is small. Make sure the soil for the cactus drains readily. The container should still be double potted.

Oleander Shows Signs of Winter Dieback

            Reports from the weather station at the UNCE Orchard in North Las Vegas put the low temperatures on December 6 and 10 at 20F with daytime highs around the same as the inside of a refrigerator. I am sure this caused some damage to plants in that area. I posted the weather report on my blog for those interested.

Q. I believe I messed up with my one year old oleanders. I covered them with old cotton bed sheets and then plastic bags thinking it would protect them. When I uncovered them, the sheets were frozen with what I assume was condensation caused by the plastic bags. I’m hoping they survive as much of the lower foliage is still green and soft. What is my next option?

 

Freeze damage to oleander in north las vegas

Freeze damage to hedged oleander and new spring growth

A. I don’t think you made a mistake. They just froze, that’s all. 9 times out of 10 they will come back in the spring. In fact the freezing bed sheet gave the oleander a few extra degrees of warmth.

            Wait until spring and new growth before making any decisions. It is possible the oleander just got some leaf and the stem death with some of the stems still alive. You will not know until it starts growing again but I don’t think you lost them.

            The degree of damage to a plant will depend on the plant itself, its variety and how it was cared for, weather prior to the freeze, landscape microclimate, the minimum temperature reached and the duration of that temperature. It can be really difficult to predict the degree of damage done for quite some time.

            There may still be some cold coming later in the winter. Sometimes freezing temperatures in February, when plants are preparing for spring, can be much worse than the same temperatures in December or January.

            Don’t prune them back just yet. Be patient and see what spring brings.

Ants Farming Aphids on Pyracantha

Q. We have a couple pyracantha bushes. We noticed this past summer some small, pen point sized, bright green bugs on the end of the branches. A day or two later I noticed ants in those same places but couldn't tell if they were eating the bugs or not. Please advise if we need to do something.

 

Pyracantha, sometimes called firethorn,, with its red berries.Some have orange, yellow and off-red.

A. From the sound of it the bush had aphids, sometimes called plant lice, but summer is not the usual time that aphids appear. Aphids normally appear with new growth in the spring and disappear when it gets hot.

            Ants are attracted to aphids because the aphids release sugary honeydew when they're feeding on the pyracantha leaves.

Leaf cupping on plums due to aphid feeding in the spring.

            Ants “farm” the aphids, take this honeydew excretion and use it. So you may see ants traveling up and down the pyracantha gathering and transporting honeydew to their nest in the soil. Ants may even move the aphids around to new locations to expand their “herd”.

            It's not a big problem if these are just aphids. The aphids will cause some stickiness on the leaves and may cause leaves to fall from the plant if the feeding becomes heavy. But that time of year I would not expect them to be a big problem.

Ants herding aphids for their honeydew

            If the problems is excessive the easiest thing to do is mix some soap and water, about as much as you would use when you would wash your dishes. Put it in a spray bottle and spray the soapy mixture directly on these green bugs, usually on the underside of the leaves.

            You will probably have to do this every couple of days since soap and water does not leave any poisonous residue on the leaf surface and these spots will repopulate quickly after the spraying is done.

            If you want more permanent control then you can use a traditional insecticide that has a label listing ornamental plants and aphid control. You can also treat the ant nest in the soil. Pouring boiling water on the ant hill will give some temporary organic control of the ants.