Garden Q&A: Potter wasps and helleborus

For The Baltimore Sun

I found this on a flower stalk in my garden when I was clearing out dead stalks. It’s about the size of a marble. Is something in it or did something come out of it? Good or bad?

This tiny replica of a jug is the work of a potter wasp. The mother wasp constructs this nest from soil and spit, then stocks it with a spider, caterpillar or similar larva. She lays a single egg near the lip and seals the jug with a mud pellet. Her egg hatches into a wasp larva, feeds, pupates into an adult wasp, pops out the pellet like a cork, and emerges. Since your nest clearly has an opening, it’s likely the adult wasp emerged successfully. Potter wasps are a huge genus of wasps and build nests in a variety of shapes. They live solitary lives (no social hives like honeybees), feeding on flower nectar and hunting to provide for their offspring. These insect predators serve our purposes and should be encouraged.

I have heaps of Helleborus orientalis. (Deer don’t eat it!) Blooms brighten my winter in February, even January sometimes. Most of this year’s leaves are still green, but the new leaves are beginning to pop up. If I cut back the old (still green) leaves now, will that leave the new ones at the mercy of the weather when it gets bitter cold? Or should I let the old leaves remain to protect the new shoots, even when they become tattered and beat up?

The recommended culture for helleborus, also known as Lenten rose, is to prune off dead leaves in late winter if they are ratty looking. That means late February or March pruning. Old leaves do not necessarily have to be removed though. They can be allowed to settle to the ground and naturally mulch the plant. For helleborus with disease problems, removing old leaves in late winter is a good sanitation measure.

University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click “Ask Maryland’s Gardening Experts” to send questions and photos.

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