Early to Mid March is a great month to do some heavy pruning on a few plants while the plants are still dormant. Need to size something, rejuvenate it or simply clean it up; this is the time of year to do it. Here is the list of plants that could use a trim.
Roses-Mid February to Early March before there buds begin to green or red tip. You want to take them down to about 2 feet tall, more if they have winter killed back further. Then eliminate any damaged, diseased branches or canes. Also you want to remove some older canes to allow room for new canes to take their place. Your target is thin out about a third of the canes. Here is a video pruning roses in Late Winter
Fruit Trees-This is a great time of year to prune the fruit trees to make them easier to spray, thin, or pick. As well as rejuvenate any old trees. The different species of fruit trees have different pruning needs so here is a pdf on Pruning Fruit Trees for Late Winter.
Summer Flowering Shrubs- Summer Flowering shrubs are shrubs that develop flowers on the current growing season's growth that have a bloom time during the Late Spring, Summer of Early Fall. With age these plants can get rangy or rough looking. A simple way to rejuvenate them is to cut them back hard up to a third of the plants original height (if they are really bad you can cut them to the ground). Then thin out a majority of the older branches, these branches are the ones that are thicker at the base. Then remove about a quarter of the branches so the plant has an open uncrowded branch habit. Here is a pdf list of shrubs that can use a hard prune ever 3 to 5 years.
Ornamental Grass-If you left them up all winter, now is great time to clean them up! Watch this video to see how easy it is.
Shade Trees- With Shade trees you can trim out crossing branches. Redirect any branches heading inward; you can also eliminate co-dominant leaders or if winter has damaged a leader you can redirect a new one.
Hydrangeas (Hydrangea macrophilea)- On Bigleaf hydrangeas the one that grow in the shade and have those large balls of blooms, you only want to trim out the winter kill. If you cut to much out they will not bloom.
Grapes-For mature grapes you can do one of two types of pruning this time of the year. Cane pruning or spur pruning. The goal of each one of these techniques to reduce the amount of fruit producing vines to ensure a quality crop as well as consistent crop cycles year after year. To spur prune you goal is to select 2 to 4 of the healthiest one year old spurs (short twigs from where flowers and grapes develop from) on the each of the main canes. To Cane Prune you want to select 2 to 4 of the best vines that are one year old, then cut them back to have only have 15 buds per cane. Keep a couple spurs with 2 buds each to allow for next year fruiting canes to develop. Then remove the other canes.
Blackberries-Prune out the dead canes and leave the new canes to develop.
Raspberries-Reduce your summer bearing varieties height by a third to promote a strong spring crop.
Evergreens like Arborvitae, Boxwood and Junipers can be trimmed to keep their shape or reduced in height. Never prune so far back that you no longer have green foliage otherwise the plant looks terrible or dies.
Things to avoid pruning this time of the year. Spring flowering shrubs like Lilacs, Magnolias, Mock oranges, Quince, Rhodies, Azaleas and Heathers; because your going to cut off your flower show. Pines, Spruces, Needle Cedars are a no go as well. Keep you hands off the Flowering Dogwood Trees and other Spring Flowering Trees unless you don't want a flower show this year!