Q. Our zoysia grass is showing brown spots. Is it a fungus or just the heat? We sprinkle it regularly and have applied a lawn fungus. One issue is that there is only 2 inches of soil under the sod.
A. Based on my experience with zoysia grass the problem is the 100-degree heat mixed with the 2 inches of soil. Zoysia lawns quickly reflect soil compacted spots and shallow soil spots when things dry out. To green up the dry spots you will have to hand water them every other day until the rains return. If it continues to be hot and dry expect more brown areas to appear.
Q. The zinnias in our butterfly garden are browning after a long season of bloom. Last year there were seedlings that sprouted from seeds that dropped from the spent flowers. I notice that there are lots of lesser goldfinches feeding on the seed heads. Is that why no new plants are germinating?
A. No, I think the issue is that the dry soil from no rain and 100-degree heat is not conducive to seed germination. You can strip some seeds from a brown flower, spread it on the flower bed, and water the area everyday for a week. The seeds will germinate. In fact, I think just watering an open area under the old zinnia plants every day for a week and new plants will grow. There is probably plenty of seed that escaped the goldfinches just waiting for some moisture.
Q. Our beautiful old oak tree is covered by fine silky webs. We noticed them in the morning sun. Do you know what it may be? Is it a problem for the tree or our landscape?
A. It sounds like a case of bark lice. When the sun hits the webs, they are amazing the way they reflect the light. The insects and the webs are not a threat to the trees or to humans. They will soon disappear from the tree. Spray them off with a hose if you want to rush the process.
Q. Last week in your article you discussed four-o’clocks as a deer proof blooming plant. What color flowers are available? Tell me again why we don’t use them in the landscape more.
A. Pink seems to be the most common. Yellow and white are also relatively common. I think that lavender and red also occasionally show-up. The seed is available in packets on most nursery seed racks. It is also easy to collect seed from naturalized beds in many neighborhoods. Four-o’clocks are hard to manage. They produce a large root system and make a sprawling plant. Apparently, you can make them more attractive if you use your pruning shears regularly. Some have a pleasant fragrance, but I spend a lot of time pulling the fast-growing plants out of the shrub border and flower beds.
Q. When do you recommend we plant broccoli transplants?
A. Plant broccoli and other winter garden vegetables in September after you have prepared the soil by adding 2 inches of compost and 10 cups of a slow release lawn fertilizer such as 19-5-9, per every 100 sq. ft. of bed. Three plants spread in an 8 foot row works well. Use drip irrigation if it is available.