Dear Problem Lady

My lovely hydrangea should be pruned, it’s a thicket. But I’m so afraid of losing flowers because I don’t know what kind of hydrangea it is, and I’ve heard that if it blooms on so-called old wood I should have pruned it after it bloomed last year. How can I tell whether it blooms on old or new wood just by looking at it closely?

You can’t, that’s the problem here. You pretty well need to know your plant’s name! Find the label it came with if at all possible. If its flowers were blue or pink, or if it’s an oak leaf variety, then it definitely blooms on old wood and should not be pruned now.

Prune any hydrangea only if it has dead or crossing branches or is too large.

The difficulty is that many of the 1,000 types of big leaf or Macrophylla hydrangeas (don’t prune now) look like the two other main types of hydrangea that can be pruned now. These (blooming on new wood) are the PeeGee, or Paniculata grandiflora, hydrangeas – of which there are some 80 cultivars – and the Hydrangea arborescens genus, of which Annabelle, with its huge white mop head blooms, is the best known.

My best advice, however, is to do nothing unless you are certain. March is already a bit on the late side for best pruning. Instead, do some research in Michael A. Dirr’s “Encyclopedia of Trees and Shrubs.”

 

Three grandchildren are coming for a whole month, without their parents. The youngest is four, the oldest seven. I’m trying to think of some gardening project they might enjoy. Any ideas?

Seeds are a great motivator – find something fast-sprouting like sweet alyssum or broccoli. But in March you will need more light – meaning gro-lights – than just a sunny window. Another idea would be to show them how the ends of existing veggies – carrots, a whole radish, a sprouted potato – will begin to produce roots and leaves when put in water. If too boring, try storybooks: “Jack in the Beanstalk,” for example.

 

What can I plant under tall trees without hurting the tree roots?

First, without covering the roots more than a couple of inches, mulch under the trees with organic humus. Then choose shallow-rooted, shade-loving ground covers, planting them as far from the trunk as you can. Try foamflower, barrenwort, Siberian bugloss, little ferns, or small spring bulbs.

 

 

The next public meeting of the Capitol Hill Garden Club is Tuesday, March 8, at 7 p.m. Jay Jensen of Potomac Rose Society will expand our horizons beyond Knock Out roses. Find membership details at capitolhillgardenclub.org. We meet at the Northeast Public Library, corner of Seventh Street and Maryland Avenue NE. Meetings are free and open to all.


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