Q. When can we divide our Dutch iris rhizomes? Do we need to plant them in new ground or a container immediately?
A. The ideal time to thin out iris is November but they are not fussy about the timing. It is great if you can plant the removed rhizomes right after they are dug but they can survive in a paper sack for a year or more if it is necessary.
Plant Dutch iris in full sun with about 18 inches between the plants. The key to success is to plant them shallow. The top of the rhizome should be level with the soil surface. Dutch iris are very drought tolerant and will grow in poor soils that are well drained or dry. Do not use mulch in the iris bed. Iris make an excellent blooming plant and groundcover for locales with deer. Deer do not eat iris.
Q. We have carpenter ants in our old live oak tree. Will they injure the tree? How should we treat them?
A. Carpenter ants do not eat live wood but they tunnel in dead wood. Old live oaks often have large areas of dead wood that can be structurally challenged if there is tunneling. It is usually best to treat the carpenter ants. Confer with your arborist if the tree is positioned to be a threat to buildings. You can usually follow the ants to their entrance to the tree and insert acephate or another insecticide labeled for ants into their nest in the tree. If use of your hose end or pump up sprayer does not do the job, refer the job to a professional.
Q. My lemons are only golf ball size but they are already turning yellow. If I fertilize them will they put on some more size before they need to be harvested?
A. No, it is too late to affect their size for this year. The fertilizer in form of a granular material for containers or a soluble fertilizer dissolved in water on a regular basis this spring and summer would have helped. The usual reason for small fruit, however is too many lemons on the tree. Next year and future years you may want to thin the fruit when it is dime size to one fruit ever 8 inches on the tree. The Meyer lemon will produce a baseball size fruit if they are thinned and well fertilized and watered.
Q. What is the best lawn fertilizer to use for the fall fertilization?
A. Use one of the fertilizers labeled as ”winterizer”. They usually offer a 3-1-2 ratio of nitrogen to phosphorous to potassium source. The nitrogen is in a fast release form. Common formulas are 18-6-12 and 15-5- 10. “Winterizer” fertilizer is also good for providing the nutrients that fall tomatoes, cool weather vegetables, and winter flowers require.