Marianne Binetti: It might feel like spring, but get out and trim those roses

The third week of March is a good time to rake, mow and fertilize the lawn, and take care of the moss invasion.

In Western Washington moss often moves in after a wet winter. Rather than killing the moss, concentrate on encouraging the grass. Moss does not kill your lawn, it is simply an opportunist that fills in open spaces when conditions are cool and damp.

Fertilizing your lawn in early spring with a slow release nitrogen lawn food will speed up the growth of the lawn, which will then crowd out the moss.

Here are a few reader questions, with answers.

Q: When is it safe to remove the old foliage from my golden Japanese forest grass? Also can I divide up my Japanese forest grass so that I have more of it in my landscape? P.T., Kent

A: You can cut back the faded foliage of ornamental grasses as early as Valentine’s Day and the reason you want to give this haircut early is to avoid cutting off the new growth now appearing. The good news is that Japanese forest grass has old brown growth that is easy to just grab with your hand and the dead foliage will pull away with a gentle tug.

Spring is also a good time to dig into clumps of grasses, daylilies, iris and other perennials and transplant sections to other parts of the garden.

Design tip: The best display of Japanese forest grass I ever saw was a staggered line of grassy clumps flowing down a hillside garden — the repeated clumps of grass resembled a river tumbling over rocks.

Q: Is it too late prune roses? There are already lots of new leaves on my shrub roses but they really are getting a bit too large. N., email

A: No, it is not too late to get snippy with roses, fruit trees and evergreens. Shrub roses, such as the flower carpet rose and knock out roses, can be pruned by shortening the entire shrub by one third to produce a more compact and bushy growth form.

The more traditional roses, such as the hybrid tea roses, can be cut back by at least one third. Always remove any branches that are dead, diseased or damaged and remember to fertilize your roses in the spring. Roses are heavy feeders and famished after their long winter dormancy.

Q: I have a rock garden plant called Iberis or candytuft. I love the pure white flowers that cover this low growing plant every spring and I have purchased more of this plant to add to my garden. My problem is the original plant now has long branches and does not look as tidy as the new plants. Can I prune this perennial to shape it up or should I just add it to the compost bin? K.M.

A: Get out the shears because candytuft is tough enough for a crew cut. Just wait until just after this rock garden plant finishes flowering and then cut it back to a tidy six inches from the ground.

In appreciation, your Iberis (candytuft) will give an encore performance and bloom a second time. In England, this evergreen perennial is grown as a low hedge, much like boxwood, to line walkways and flowerbeds. Gardeners use a string trimmer to shear it after blooming and this keeps the plants low and in flower for most of the summer.

This story was originally published March 19, 2016 at 7:48 AM with the headline "Marianne Binetti: It might feel like spring, but get out and trim those roses."