Beware the toxic four o’clocks in your garden

Q. I recently read that four o’clocks were poisonous, yet Japanese beetles love them. Is this a way to get rid of Japanese beetles?

A.

Plants that are poisonous to us may or may not be poisonous to animals and insects. And vice versa. You are right: Japanese beetles love to dine on four o’clocks, and according to several university sources these plants are poisonous to them. They are also toxic to people and pets. They can cause vomiting and diarrhea if eaten and the sap can cause dermatitis. Keep pets and children away from the plant to avoid problems.

Q. I am trying to prune a really old lilac. Are there supposed to be any leaves left on the plant? I first pruned it back with the hedge clippers and then removed a third of the older stems to the ground. The remaining branches only have leaves on the top 6 inches. I have always sheared it in the past but it just kept getting out of control. Your thoughts?

A.

Regular shearing, as you have been doing, creates a veneer of greenery at the branch tips and results in bare stems in the center and at the base of the plant. This explains the limited number of leaves remaining on your plant.

It is best to remove a third of the older stems to the ground first. Then reduce the height if needed. That way you can adjust your pruning to ensure the plant maintains sufficient foliage to rejuvenate.

At this point, leave the plant alone. Next year, take another third of the stems back to the ground and minimally reduce the overall height. By the end of the third year, your plant should be much shorter and have leaves from the tip of the branches to ground level.

Q. This year, we bought cocoa bean shells for our containers. I went to add a plant to the pot and found white threadlike 14-inch worms under the shells. They can jump but do not appear to be damaging the plants. Have you heard of these?

A.

We occasionally see very small, 1/16- to 1/8inch white jumping insects called springtails in mulched areas. These insects feed in damp locations on the organic matter in the soil.

The larger white worm-like insects may be cheese skippers, according to the University of Illinois Extension entomologists. These insects are typically a pest of decaying cheese and meats but may live on other food when these are not available.

There have been several reports of cheese skippers in gardens mulched with cocoa bean shells. Our wet spring and summer along with the cocoa bean mulch created a good environment for these pests.

Allow the soil to dry beneath the mulch to avoid fungal growth and insects, like these, feeding on the rapidly decaying organic matter.

Q. I have a spikey plant that developed a flower stalk after four years in this home. The blossoms are white and hang upside down. Any ideas?

A.

Sounds like a Yucca filamentosa, also known as Adam’s needle. These heat- and drought-tolerant evergreen perennials prefer full sun and welldrained soil. These North American natives attract butterflies and hummingbirds. And don’t be alarmed if the plant does not bloom next year. They often flower only every other year.