Q. We are growing some redwood trees on our property in containers. Some of them on the south side of the home that have been in containers for several years have branches dying at the bottom. Younger ones in containers on the north side seem to be doing well.
A. Congratulations that you are trying to grow something different than what is found in the local nurseries and garden centers. I encourage people to push the limits of their environment by growing a variety of different plants. But remember, whenever growing plants, like redwoods, that don’t belong here you will need to invest more time, energy and money to get them to grow here.
|Redwood tree in its natural habitat with man posed in front of it for perspective. From Wikipedia https://en.wikipedia.org/wiki/Old-growth_forest#/media/File:Redwood_M_D_Vaden.jpg|
Soils in containers become “exhausted” in a couple of years and must be renewed. I try to relate it to a fish aquarium. Periodically about one third of the water in an aquarium should be removed and replaced with fresh water. In a similar way, about one third of the soil in a container should be removed and replaced with fresh soil every 1 to 2 years.
|Adding new soil to a container is like changing the water in an aquarium. Both rely on replacement to keep the arguments healthy.Picture is from Wikipedia https://en.wikipedia.org/wiki/Freshwater_aquarium#/media/File:Aquarium_60cm.JPG|
The second problem is the mature size of this plant. If you want this plant to grow for any length of time at all it should be grown in the ground, not in a container. These trees will get much too large to maintain in containers.
The third problem is exposure. The south side of the home is much hotter than the north side. Plants that do not enjoy our desert environment perform much better on the north side, in the shade, than on the south side exposed to intense sunlight and heat.
Even if the trees are protected from exposure by a house or other building, when they grow above this protection you will begin to see damage to the exposed parts of the tree in our climate and soils.
A fourth problem is our tap water. About three fourths of it comes from the Colorado River and contains a high amount of salts. Redwoods do not like salts in the soil or the water and the salts will cause problems for these trees in containers.
Your trees are probably “root bound” with spiraling roots that will never become established even in the best landscape soils. If you want to keep them, put them in the ground on the north side using improved soil and stake them for support. Enjoy them for as long as you can but realize that eventually they will succumb to our desert.