Q: We live in a gated community with beautiful trees and walking trails. The little house with patio we bought is surrounded by eucalyptus trees which are dropping leaves etc. continuously. We have a small garden. I have trouble growing hydrangeas. I planted several in different places trying to find the right spot but they don’t survive. I have also inherited several roses which are struggling to flower despite the fertilizer. Leaves are in all flower beds. Is eucalyptus oil toxic to plants?
A: Many plants produce compounds that inhibit or stop the growth of neighboring plants to better compete for nutrients, sunlight, and other resources. This phenomenon is known as allelopathy. Black walnut, maple, pine and eucalyptus are more well-known examples. If you want your hydrangeas and roses to thrive, I recommend planting them away from eucalyptus trees.
Alternatively, you can try growing them in containers, being careful to remove any eucalyptus leaves that land on the potting soil.
Q: We recently had a very old, very large ficus removed because the roots were causing damage. We hated seeing it go because it was beautiful and offered a lot of privacy (we live in a condo complex with two story neighbors all around us). When it was pulled out, they crushed the roots to about six inches deep. We want to plant another tree in the same area but hear that this might not be possible due to lack of nutrients. What do you think and what type of tree (and what size) would you suggest to offer us beauty and privacy all year round as quickly as possible?
A: Whenever an old established tree is removed, there will still be some roots remaining, even if the first 6 inches of root structure has been crushed. Many trees can reappear from these remaining roots and can become a maintenance problem for years. Ask someone who has tried removing an established mulberry tree and you will hear all about ‘zombie trees’. The fig, olive, princess Paulownia, and silver maple are among the worst offenders.
If you recently removed a large tree and the roots continue to sprout, you may need to use a stump killer. Once the tree and its roots are completely dead, they will eventually decompose in place. If you try to plant something in this spot too early, the roots of the new tree may be squeezed out by the remaining intact roots of the old tree.
If you’ve waited and are confident that the previous tree won’t attempt to respawn, you should be able to plant a replacement in the same spot. The choice of tree depends on the amount of space available, height requirements, sunlight, and the location of structures such as patios and sidewalks. Privet, boxwood, photinia, and podocarpus are popular choices for Southern California.
Have questions? Send an email to [email protected].
Looking for more gardening tips? Here’s how to contact the Master Gardener program in your area.
Los Angeles County
[email protected]; 626-586-1988; http://celosangeles.ucanr.edu/UC_Master_Gardener_Program/
Orange County
[email protected]; 949-809-9760; http://mgorange.ucanr.edu/
Riverside County
[email protected]; 951-683-6491 ext 231; https://ucanr.edu/sites/RiversideMG/
San Bernardino County
[email protected]; 909-387-2182; http://mgsb.ucanr.edu/