Pot-in-pot production protects plants

There has been some damage to trees in the valley due to snow accumulating on their branches and breaking limbs. Trees that I know of that were damaged include olive, pine, pepper, African sumac, mesquite, ash and Italian cypress. In some cases, the snow did not break limbs but bent them downwards out of their normal shape.

If there were limbs broken, it is best to remove them from the trees completely rather than try to mend them. Make clean cuts and remove the broken branches at their point of attachment to the trunk, major limb or side branch. In other words, don't leave a stub to regrow. Remove it or cut it back to a place that is already growing, particularly in a favorable direction of growth.

You do not need to "seal" the wound with pruning paint, Elmer's glue, Grandpa's mystery concoction or anything else. The tree will heal itself. But I would make sure the pruning instruments are clean and have been sterilized with alcohol or other sanitizer before making the cuts. You are cutting into clean, living tissue.

The area where the limbs were broken will recover, however most likely not in the same way. Areas of the tree that were previously shaded and are now exposed to sunlight will try to send out new shoots -- a proliferation of them. The exceptions to this are ash and pine. They don't do that. The area where there were broken limbs will probably remain void and the tree will not recover in that spot.

Italian cypress damage is mostly from stems bent out of shape. They will not bend back; that bending is permanent. You can remove those bent stems, however. I would suggest cutting them at a point inside the tree and out of sight rather than just cutting the branch at the edge where the cut can be seen. If the stem is not very old, it is possible that it will regrow. If it is older and larger in diameter, it will not.

Let's reduce what we put into our public landfills. If you have one, recycling your Christmas tree is a gift that gives back to the community. The trees are turned into mulch. There are no fees to participate, just a small amount of your time. I am asking all of you to take your Christmas trees to one of more than 20 convenient drop sites now through Jan. 15.

Before dropping off your tree, please remove all nonorganic objects such as lights, wire, tinsel, ornaments and nails. Foreign objects contaminate the mulch and damage the chipper. Flocked trees cannot be recycled.

For more information about the Christmas tree recycling program, drop sites nearest you and other ways that you can have sustainable holidays, visit www.springspreserve.org, or call 822-7700.

Q: I got this tiny oak tree and a new iris from the Springs Preserve. This spring I transplanted them into small containers and good soil and they've taken off like crazy. My concern is that I need to leave them outside to go dormant this winter but am afraid the roots will freeze in the small pots. This goes for my other perennials as well, which are in larger pots.

I have placed my smaller pots in larger ones throughout the summer to avoid direct sun on the smaller pots but have a huge problem with cockroaches and other critters taking up residence in the larger pots. I don't like pesticides. I really don't want to lose them and I'm afraid the smaller potted plants just won't make it when it really gets cold.

A: Another method you could try is to bury a larger container in the ground. Nestle the smaller container into the larger one. Use this larger container to protect the smaller container through the winter. Both containers must have holes in the bottoms for water drainage. The earth will protect the smaller one from cold winds, which are a major culprit in lowering the temperature in the smaller containers. It also allows you to remove the smaller container any time you want to.

In commercial situations, this is called pot-in-pot production. It is used to help reduce the wind from blowing over nursery containers and add some protection to the root balls from both summer and winter extremes.

You also can bury just the container in the soil through the winter but the danger you face is that the roots will grow through any holes in the container and root the plant into the ground.

In pot-in-pot production, the larger container is slightly larger than the smaller one and a layer of gravel is put in the bottom of the larger container. This gravel layer keeps the two pots from lodging together and allows for easier removal of the smaller pot.

About once a month you have to twist the smaller container a quarter turn so that any roots that might be growing into the gravel will be severed. If you do not do this, the plant's roots will find their way through the holes in the smaller container into the gravel and then through the holes in the larger container into the soil. Then you will have a problem.

As soon as most of the cold winter is over, around mid-March, take them out of the ground or the roots will grow into the soil beneath the container. In fact, they may still do that even though it is cold.

If it were me, I would want to use the soil as a temperature and moisture buffer rather than leaving the small container open to outside air temperatures. The temperatures would widely fluctuate from day to night in such a small container.

As far as your concerns over our Las Vegas water bugs or cockroaches, they like to hang out wherever there is water. Outside, this is usually in irrigation valve boxes. I realize that you don't like pesticides, but, for other readers, the solution is to apply a treatment to these boxes and anywhere else there is a source of water. This will help reduce numbers.

There are a lot of claims out there on organic control methods for these critters, but I do not know of any surefire method for control.

Bob Morris is an associate professor with the University of Nevada Cooperative Extension. Direct gardening questions to the master gardener hot line at 257-5555 or contact Morris by e-mail at morrisr@unce.unr.edu.