Getting rid of grape hyacinths -- or not

Dear Jessica,

I have a circular driveway in front of my house and a garden in front of this driveway. In the garden, which was planted in 1987, I have trees and shrubs. Unfortunately, I also have lots and lots of grape hyacinths. Over the years, I have dug them up, but somehow they keep coming back with a vengeance. I do not want to put killer down as I do not want to kill my shrubs or trees. What can be done?

Phyllis Eisman, Baldwin

Dear Phyllis,

I'm not sure why you'd want to do anything. Grape hyacinths (Muscari) are among the first plants to bloom in spring, with grape-cluster-like flower clusters above 8-inch-tall stems. They're frequently planted in garden beds and in lawns for an early blast of color. They do spread quickly and continually each year, but the show typically lasts only a couple of weeks.

The recommended advice for ensuring repeat performances from year to year is to allow the foliage to remain on plants until it withers, as the leaves need that time to collect sunlight in order to produce food, which is used for blooming energy the following year. If you don't want them to return, and they are too prevalent to dig up, just reverse the advice: Cut or mow them to ground level as soon as foliage emerges, and repeat weekly throughout the season.

It may take a few years, but repeatedly mowing them down will starve them and reduce reproduction until, eventually, they won't have enough energy to return.

Dear Jessica,

I am quite alarmed because all of my hydrangeas have lost their leaves. There were no blooms last summer, and I do recall you discussing this although I don't remember why. Perhaps it was the bitter cold winter. However, I'd like to know if the leaves will come back, and if they will bloom again? I will be devastated if I lose them.

Doris Buxbaum, North Merrick

Dear Doris,

You don't say when your plants lost their leaves nor whether the leaves grew back last summer.

Hydrangeas typically lose their leaves in autumn on Long Island. Many were slow to break dormancy last year due to the effects of the extremely cold winter of 2013-14. With few exceptions, the most popular hydrangea species -- hydrangea macrophylla -- bloom on old wood, which is the prior season's growth. If yours did not bloom last year, but had leaves and were otherwise fine, you can be fairly certain the deep freeze inhibited last year's buds. They should regain their vigor and bloom this year or next.

If, however, they never leafed out last summer, it's pretty safe to assume they're dead, having succumbed to the previous winter's harsh weather.

Dear Jessica,

I noticed that in your February 2015 calendar, you advise waiting to prune sycamore trees until the leaves come out.

Last fall, a local expert told me it would be safe to prune mine in March. Your advice is different. Since my mother always arranged the pruning, I did not know what time of year this should be done, and I am now confused. It really needs a shaping and thinning. Should I wait until May? June?

Ricki Sokol, North Bellmore

Dear Ricki,

The reason I recommend that so-called bleeder trees not be pruned until after their leaves have grown in spring is because these trees have a heavier sap flow than many other types of trees.

In late winter and early spring, which is the ideal time to prune most deciduous trees, they are busy preparing to break dormancy. Sap is flowing up from roots to transport nutrients throughout the tree. If cut when this process is occurring, "bleeder" tree species -- such as maple, beech, dogwood, elm and sycamore -- tend to lose an excess of sap from their cut limbs.

This is only a concern, however, if the limb you are pruning is bigger than 3 inches in diameter. It's perfectly fine to cut smaller branches in late winter.

It's difficult to provide an exact time frame for such pruning. Plants can't read calendars, and weather fluctuations from year to year can alter their schedules, from leafing out to blooming and entering dormancy. They react to temperature trends, so the best thing to do is to let them tell you when to prune: Wait a couple of weeks after they have fully leafed out.