Dear Problem Lady

You warned us that dahlias were a lot of trouble. I forget how I’m supposed to over-winter them. Hang them upside-down in the garage? We don’t have a garage.

First carefully dig up each dahlia bulb. Shake off all soil. Lay them down for about a week on dry newspapers not touching one another, until they are completely dry. Layer the bulbs in a cardboard box, again not touching, between layers of crumpled newspapers. Place the box in a cool (40 degrees F) dark place away from any possibility of freezing. Check every six or so weeks. If any bulb looks desiccated, spritz gently then dry and return to storage. Remove them only after any danger of frost has passed. If in doubt, plant first indoors in pots. After three leaf sprigs have sprouted, snip growth back to one sprig. Plant soon in good soil. Dahlias are divine and, you now see, worth it.

 

I am new to Capitol Hill from Alexandria, Va., where swarms of Japanese beetles consumed my roses to such an extent that I will never even attempt roses again unless I can be sure to find a way to prevent those beetles. Ideas?

Integrated pest management (IPM) principles say we must anticipate and foil the life cycle of the beetle. This means either preventing the beetle’s eggs from existing – or killing the grubs (larva) that hatch and over-winter in the ground. Kill the eggs by killing each beetle by hand (soapy water) in the morning. Kill the grubs by watering with nematodes or insecticide in the fall and spring. But neither will work if the beetle onslaught is heavy. Some localities seem to be free of beetles (also known as chafers, chiggers, or thrips) – and roses do proliferate here on Capitol Hill. Let’s hope yours survive.

 

What are nematodes?

Beneficial nematodes are a kind of tiny worm that kills a variety of pests, including weevils, clearwing borers, cutworms, sod webworms, chinch bugs, and white grubs. Buy the right kind for your purpose – grubs. Follow application directions carefully.

 

“Water, water ‒ but never on the foliage.” Please tell me why directions for watering always say not to water plant foliage and NEVER water in the evening. A twilight rain shower – or even a deluge – is not deemed harmful – but they call me and my garden hose killers in the evening!

Damp leaves attract plant-eating slugs. If we water in the morning, leaves get all day to dry in the daylight.

 

The Capitol Hill Garden Club’s Nov. 10 program on DC’s Master Gardener Program convenes at 7 p.m. at the NE Library, corner Maryland Ave. and Seventh Street NE. For more information about the Capitol Hill Garden Club please visit capitolhillgardenclub.org.


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