Ornamental grasses are due for a trim
The end of February is a good time to cut back any ornamental grasses that turned brown and dormant over the winter.
Cutting back grasses early in the spring means the fresh new growth won’t be tangled with the old brown duff from last year. It doesn’t matter much if you use hand pruners, electric trimmers or hedge shears to take off the old dead growth.
As long as you cut the old grass blades down to stumps now, new growth will soon cover up all those pruning stubs in just a few more weeks.
Your lawn grasses can also use some attention this week. Add lime now if you have not yet done so and apply a spring lawn food this week as your grass comes out of winter dormancy. Feeding the lawn early in the spring is a good way to prevent weeds later in the season. Weeds are opportunists, growing where empty soil is available for rent. Encouraging a quick, spring growth in your lawn will crowd out weeds later.
Q. I love that you are giving talks in my neighborhood about gardening in dry shade, but I cannot attend these talks. Just tell me what I can plant that will live under my cedar and fir trees. — P.M. Sammamish
A. The plants that I recommend for growing beneath the dry shade of large trees are natives such as sword fern and mahonias, tough evergreens such as nandina or heavenly bamboo and groundcovers with colorful foliage such as creeping Jenny, ajuga and lamiums as well as woodland bulbs such as the hardy cyclamens and dwarf daffodils. Euphorbias, sedums such as the golden sedum “Angelina” and low-growing evergreen shrubs of euonymus fortunei “winter creeper” will also survive the competition of large tree roots. The garden tip to remember is that all new plants will require water the first summer as they establish a good root system that can compete with the trees. A mulch on top of the soil and digging a wide hole at planting time are other tips to creating a drought-resistant paradise in dry shade.
Q. Why doesn’t my bearded iris bloom? They flowered beautifully a few years ago. They get full sun. Could the slugs feeding on the foliage cause them to stop blooming? — H.S, Tacoma
A. No need to blame the slugs. Most likely your iris needs dividing and feeding. Fall is the best time to dig and break apart iris rhizomes (the knobby, shallow roots) but you can also do this deed in early spring.
To do that, dig in and lift the entire clump from the ground. Use a sharp knife to cut into the joints of the iris clump so that each new section has several knuckles of root extending from the center. You can divide iris roots into smaller segments but then you will miss a year or two of blooms while the roots grow larger. Iris need well-drained soil so do not add too much compost to the planting area but do add a slow-release plant food. Be sure not to plant the rhizomes too deep. They should sit horizontally just below the surface of the soil. Bearded iris are heavy feeders just like roses. For this reason they respond well with an abundance of blooms if given both a liquid plant food in April or May and a slow-release plant food in early spring. Finally, protect the new growth of your iris from slugs by using pet-safe slug bait such as Sluggo or Worry Free.
Q. I have a Pee Gee hydrangea and want to know when to prune it. —T. email
A. Go grab the pruning shears now because early spring is the time to prune Pee Gee hydrangeas. The Pee Gee is the common name for the hydrangea paniculata and unlike the more common hydrangea with round blue blooms, this variety has smaller leaves and pointed flowers that start out creamy white and fade to pink, russet or lime green. This is the hydrangea that can take full sun and is often sold trained as a small tree rather than a rounded shrub. Prune by removing any crossing branches and shortening up long branches by at least one third to shape the plant. The fewer branches the Pee Gee hydrangea has to support, the larger the blooms it will produce.
Marianne Binetti has a degree in horticulture from Washington State University and is the author of several books. Reach her at binettigarden.com.
This story was originally published February 25, 2017 at 3:47 PM with the headline "Ornamental grasses are due for a trim."