Q: I ordered six tree mallows (Lavatera) from a catalog last year. They grew to more than 6 feet tall and were covered with flowers almost the whole summer. This summer, however, three of them died and the other three look less than healthy. I pruned them back last winter and fertilized them on a regular basis this year but nothing helped. I don’t know if I did something wrong or if they are simply not suitable for our climate.
– Nektar Hovanissian
A: Tree mallows, as well as the related cape mallows (Anisodontea), are highly suited to our climate as long as they are given excellent light and good drainage. Since your mallows did well their first year in the ground, I would suspect something happened this year that caused their failure. It could have been the weather, which was significantly hotter this summer than last. The hot weather may have caused you to overwater your tree mallows. These plants are highly sensitive to excess soil moisture, developing fungus in their roots that can quickly kill them. The fact that you fertilized them on a regular basis could have also led to their demise. Mediterranean and California native plants, among them tree mallows, should be fertilized in late winter, if at all, but not during the growing season.
Q: I planted five horsetail plants in redwood planters that faced south but got little sun due to an awning. The soil was organic potting soil and I watered a lot. My horsetail plants proceeded to get yellow and mushy, then brown, and eventually died. The nursery said not enough sun was getting through for the plants to make chlorophyll, but I find that hard to believe; I have seen horsetail growing in shady areas. Another suggestion was that I overwatered; is that possible? Please help me figure this out.
– Zoe James
A: It appears that you have made two common mistakes of novice gardeners. Your first mistake is to assume that plants that grow in the presence of shade will grow just as well in the absence of sun. Time and again I come across exposures that lack the amount of light required for even the most shade-tolerant species. In such cases, I recommend placement of river rock or smooth stones, or installation of a fountain. Nowadays, you can find small, inexpensive fountains that make a shady corner so much more interesting and elegant than a struggling horsetail, aspidistra or mother-in-law’s tongue (Sansevieria) could ever do. Another mistake you made was to use organic potting soil for your horsetail. Horsetail is an outdoor plant that grows best in ordinary dirt and may develop root fungus, or become susceptible to anaerobic bacterial infection, when cultivated in fancy organic soil mixes.
Q: I have some Concord grape plants growing from cuttings I put in the ground last year. My question is: When is the best time for transplanting them? I have tried with some before, but they haven’t done as well as I had hoped.
– Chuck McCammon
A: The answer to your question is now. October is the best time to transplant just about anything since this is a period of rapid root growth. You want your root system to establish itself far, far in advance of the Valley’s long, hot summer, which can start as early as the first week in April.
Q: We have a beautiful grapevine that every year starts very healthy, but by the time it gives us some small, dried-up grapes, the leaves have turned rusty as if burned. Also, we have an apricot tree that, in the past six years, has given fruit only once and a peach tree that needs help. What should we do? By the way, we have many healthy citrus trees that produce nonstop.
– Tamar Piloyan
A: Your closing remark, together with the problems you mention, is an excellent guide, in a nutshell, for those making decisions about which fruit trees to plant in the Valley. The easiest and most reliable fruit trees to grow in our area are citrus. Deciduous fruit trees and vines, which are native to cold winter climates, will always be more problematic here since our winters are mild. Hopefully, your grapevine is being scorched because of a fungus. Eradicate all burnt leaves and prune your vines so that air circulation through them is excellent. Also try not to get water on the leaves when you irrigate. Alternatively, your grapevine may have Pierce’s disease, a fatal bacterial affliction that is carried in the saliva of leafhopper insects. After a grapevine contracts this disease, it will die within five years. Make sure your apricot and peach are getting full sun and are varieties that produce even where the winter climate is mild.
Tip of the week: An attractive arrangement for fall containers includes bronze or violet flowering chrysanthemums, ornamental cabbage or kale, red cyclamen and any of the currently flowering ornamental grasses.