White spots on ficus are there for a reason

Here are questions I recently dealt with at the Springs Preserve.

Question: What are the small, whitish and waxy pinhead-size bumps on our ficus tree leaves?

Answer: They are waxy, glandular spots, characteristic of ficus plants. Anytime you find something on a plant so uniformly spread and so consistent, it's not an insect. Insects are rarely organized.

It's been postulated that the spots exude a substance that attracts fig wasps, which pollinate the plant, but no one knows for sure. They must serve some purpose, because nature never does anything just for fun.

Q: What is this weird-looking insect that looks like a praying mantis but is tan?

A: Praying mantises become tan in the fall to disguise themselves from predators. The insect is still laying egg cases throughout your garden. This is how it propagates itself from one season to the next, so be good to them.

I always thought praying mantises were docile insects praying for insects to land in their "arm traps," but I'm wrong. I witnessed two mantises fighting over an insect with one arm hanging on the wall and the other arm trying to trap an insect. They put up a good fight.

Q: Spurge covers the ground cover under our roses. Can we use an herbicide to control it and not hurt the roses?

A: The easiest control is to moisten the soil and pull out the spurge. The spurge freely disperses seeds so handle the weed carefully to prevent a problem next year. Next year, hoe out the seedlings as they emerge or apply a pre-emergent herbicide.

Q: What do I do with my rhubarb now that it's growing? Back east we mowed it off.

A: Do the same here and then mulch over the crown. Rhubarb jumps back quickly next spring. I hope you realize, though, that Las Vegas-grown rhubarb won't be what you're dreaming about nor will the stems turn strawberry red.

For other people who might want to grow rhubarb, it's best to place it on the northeast side of your home, where it gets the coldest and will have relief from the summer heat.

For those new to rhubarb, its leaves contain a poisonous substance; however, the leaf stalks are all right to eat. Also, don't expect much rhubarb the first season.

Q: When is the best time to spray my fruit trees with dormant oil?

A: Just before they bloom. Spraying them any earlier is a waste of time and oil. The oil coats insect eggs to suffocate them. Spraying earlier, when the bug's respiration rates are slow, doesn't bother them.

Q: When do I cut back my pampas grass?

A: Enjoy the plumes until they lose their luster, but don't remove the greenery until February. Cut it back to a foot above the ground. Do it every year to keep it looking fresh.

Q: Can I mix in sawdust with my compost?

A: Yes. But add nitrogen, as microorganisms need it to break down the sawdust.

Q: Do I need to remove grubs I'm finding in my compost pile?

A: No. Those bugs are assisting the microorganisms already there.

Q: What kind of vine does best on a west-facing wall with our heat?

A: Try Hall's honeysuckle, cat's claw, Bank's rose or grapes. I'd plant grapes as the vines provide cover and produce food.

Q: Should I put Epsom salt or magnesium sulfate (same thing) on my lawn as well as roses?

A: We have plenty in our soils to satisfy lawns. Try to tell rose enthusiasts there's enough, though, and you'll be in for a fight. They find it stimulates new cane growth, improves overall plant vigor and makes blooms last longer.

Q: What flowers can I sow in the yard to flower next spring?

A: Consider forget-me-nots, California and Shirley poppies, bachelor's button, larkspurs, sweet peas and Johnny-jump-ups. They'll generate larger plants for a more bounteous crop of flowers next spring if planted now.

Q: How do you divide red yuccas?

A: Pop the clump out of the ground and separate the plants. Before replanting them, allow the transplant roots to dry in a shaded area to allow cuts to "seal."

GROWING HERB WORKSHOP

Herbs are marvelous plants. They're easy to grow, versatile and tasty. This workshop focuses on growing them, making sachets and bouquets to fragrance your home and adding gusto to your meals. It's at 8:30 a.m. every Saturday and Sunday through November at the Springs Preserve, 333. S. Valley View Blvd. I teach the Saturday class.

Linn Mills writes a garden column each Sunday. You can reach him at linn.mills@ springspreserve.org or 822-7754.