Growing Concerns 529: Non-blooming hydrangea, sickly trees

 Late Summer!

Non-blooming hydrangea is aggravating but sickly trees are serious trouble


Dear Readers,

Usually, questions slow down during the dog days and I catch up on what I missed in spring and early summer. Not so, this year! Here are brief reports on the three hottest topics:

For blue and pink hydrangeas that didn't bloom..

...or bloomed only on short, low branches: That's a hardiness issue, not a question of when you pruned or how you fertilized. The blue and pink blooming hydrangeas are not reliably hardy in some zones. Their branches often die back over winter, and new growth begins from the roots the next spring. Yet these species flower only on growth that begins in spring from branch tips which matured the previous year. If branch tips are killed over winter, the plant is no longer primed to flower.

If your hydrangea has no flowers at all, move it to a spot that's better protected in winter. If it still doesn't flower, try another place.

If there are flowers low on the plant but nowhere else, that means only the branch tips near the ground survived the winter. You might bring more of that plant through winter by ringing it each December with a wire cage wider and taller than the plant, then stuffing that cage full of airy insulation such as oak leaves or pine needles. Even more sure, you can use the Minnesota Tip method to bury it!

Oaks, maples, birches, sycamores, poplars, elms and other trees in trouble.

It was a killer of a winter, damaging many plants' roots and circulatory systems. Many trees are not as leafy as they should be or have dead parts that just didn't leaf out this year. Others leafed out late and slow, with dwarfish leaves. Quite a few of these stressed trees, like people with compromised immune systems, have developed secondary problems such as leaf spot and anthracnose or succumbed to blights and wilts because their resistance is way down. Some seemed fine until a few weeks ago when heat and drought peaked, and now every leaf on the tree or on particular branches is shriveled, dry and hanging.

The best thing you can do is to be sure these trees are watered regularly and have adequate nutrients. Water whenever the soil is dry, applying enough to penetrate several inches deep from the trunk to the dripline of the branches and beyond. It's not a good idea to fertilize woody plants right now, but plan to apply a slow release fertilizer in October after leaf-fall begins.

It's likely that the trees' roots as well as tops were damaged so they cannot even absorb normal amounts of water and fertilizer. Like a person being nursed back to heath from the point of starvation, they must be given small meals frequently. That's why you should use a slow-release fertilizer or apply whatever you use in small doses spread through October, April, May and June.

These trees need pampering and time. Forgive their ragged looks right now and understand that you may see no real improvement until next spring.

The bigger the tree, the longer its recovery time may be, so keep babying it until you see it return to its normal color, density and growth rate. Some oaks, first damaged in the drought of 1988 and hurt repeatedly by drought and two severe winters since then, may need a decade of extra attention before they are glossy green rather than sickly pale yellow.

Garden's not as colorful as it should be?

Many annuals did not grow as large as usual and remain less vigorous and floriferous even now  because of the cloudy, cold spring. Cold soil and lack of sun stunted them and secondary problems like stem infections on marigold and impatiens or leaf spot on begonia and geranium continue to sap their strength. Where annuals are very disappointing it may be best to remove them early. Fill in with asters, mums or flowering kale.


Green thumbs up

to sharing vegetables from your garden with those in need.


Green thumbs down

to expecting any one garden center to carry everything. With tens of thousands of plant varieties available for growing in gardens, of course one store can't stock them all. Do ask for the plant you seek, though. The more we ask, the more likely the store's buyer is to order that type next year.


Originally published 8/16/03