How to keep lesser goldfinches in the landscape

Q. What is the best way to keep lesser goldfinches in the landscape? They visited our sunflower seed feeders this winter but we need to quit feeding seed for a while so we can reduce a rat problem.
A. Feed Niger thistle, it is less attractive to the rats and you can hang one or more tube feeders on the patio at a location where it is easy to observe the goldfinches. Another option is to grow sunflowers and or zinnias away from the house. The goldfinches love both seeds and a garden patch is less likely to support the rats.
Q. We have a zoysia grass lawn on our new house. It is attractive and grows slowly so we do not have to mow very often but when we mow the lawn looks scarred. We are mowing it two inches tall with a rotary mower. One neighbor suggests that zoysia grass needs to be mowed by a reel mower. Is that true?
A. Zoysia grass is more difficult to mow than Bermuda or St Augustine grass. It is easiest to mow with a reel mower because it cuts rather than rips. A rotary mower works okay if you keep it sharp and you mow every week. It does not work well if you wait a longer period between mowing.
Q. We are building a retaining wall and the effort resulted in three of our six post oaks in the construction area being killed. Now it appears we must revise some of the wall. Are there any precautions we can take so the remaining trees will not die?
A. I do not know of any. Post oaks will often die if vehicles drive over their roots or the ground is disrupted. Contact one or more arborist in your area to see if they have any tactics that will reduce the threat to the post oaks. If you lose the remaining three post oaks, plant live oaks, Mexican oaks, or chinkapin oaks, all of which are much more tolerant of activity in their vicinity. Good luck!
Q. Our summer squash was destroyed by squash vine borers. A friend who is a Master Gardener suggests that we spray the growing point every week with Sevin to control the borers. Do you think it will work? Is there still time to replant this summer?
A. Squash vine borers are difficult to control. The weekly insecticide spray on the growing point sometimes works but not always. The option I would choose would be to grow Mexican squash (tatuma). It tastes the same, is easy to grow and is not usually bothered by squash vine borers. Unfortunately, it is late in the season for a new planting. Wait until this fall.
Q. How long should we have to run the sprinkler on each section of the lawn? It is St Augustine grass in full sun. There is at least six inches of soil.
A. With six inches of soil you should be able to operate your irrigation to provide .75 inches of water each week for the lawn. Sprinkler systems are so different you will have to do a timed test to determine how much time it takes to apply .75 inch.