Both trees and shrubs (such as roses) and ornamental grasses (such as pampas and northern sea oats) benefit from pruning in late winter. Trees are dormant in late winter, so pruning will minimize shock and help the tree recover faster. Ornamental grasses should be trimmed just before new growth occurs in springtime. By delaying pruning until late winter, you avoid damage by harsh winter cold and provide visual interest to your winter garden throughout the majority of the season.
Put on protective clothing including long sleeves, long pants, sturdy work boots and heavy gloves. If you are pruning a tree, add a hard hat to this protective clothing. Many ornamental grasses such pennisetum and miscanthus have razor-sharp blades that can injure you when you cut them, while roses and other shrubs have thorns. Protective clothing will help you avoid injury. Additionally, a hard hat will protect you from falling debris when you prune limbs from an ornamental tree.
Sharpen your pruning tools prior to using them by drawing a whetstone along the length of the blade. Tools for pruning trees, shrubs and ornamental grasses include hand shears, branch loppers, a hand saw and a pole saw.
Prepare a sterilizing solution containing one part bleach and nine parts water. Soak a cloth with this solution and wipe the blades of your tools in between pruning each plant or after removing any diseased plant parts in order to halt the spread of diseases.
Use the pruning tool best suited for the piece of plant you plan to remove. Hand shears are perfect for plant parts smaller in diameter than a pencil. Branch loppers are suited for plant pieces smaller than 2 inches in diameter. Hand saws or pole saws are ideal for plant parts that are 6 inches in diameter or less.
Remove all dead plant parts first. For ornamental grasses, this will constitute the majority of trimming. Grasses such as pampas may require trimming to the ground, while a plant such as monkey grass may only need slight trimming.
Take off any weak or broken branches, or plant stems that grow too closely together. You should also remove any branches that grow toward the center of your plant.
Excise any diseased plant pieces and tiny offshoots from the base of the plant that would steal the plant's energy. These tiny shoots are known as suckers.
Thin plants with bushy growth by removing one-third of the weakest growth from the canopy to let light into the heart of the plant. Shorten the limbs of plants that have grown too tall in a process known as heading back. Cut each plant back to a bud or stem that will sprout a new branch.