Steele: Spring gardening clean-up for the unH2O garden

Last weekend, many gardeners helped with spring clean-up of perennials and ornamental grasses in the unH2O Xeriscape Demonstration Garden.

Last weekend, many gardeners, including master gardeners, helped with spring clean-up of perennials and ornamental grasses in the unH2O Xeriscape Demonstration Garden.

Their assistance was much appreciated in this volunteer maintained garden. The garden, planted in 2010, has grown faster than expected due to very good soil and the nitrogen-rich Ogogrow mulch.

Many plants needed dividing. Saturday provided a day of learning about plant division as well as spring clean-up.

Many plants were divided to avoid overcrowding. Excess plant material has been removed from the garden for potting up for the Xeriscape Plant Sale to be held in the garden in front of the H2O Centre, 4075 Gordon Dr., on April 28, 9 a.m. to noon.

The ideal way to plan renovations is to make notes and take reference photos during the growing season.

What I often rely on is the dead standing vegetation after winter, deciding how much to reduce the plant size before I cut it down.

Some plants are very easy to divide. A single stem of a ground cover plant that has roots along its stems can grow into a new plant. A single rosette with stem from a stonecrop will root.

Once dug up, plants such as bluebells, tall sedums, blue oat and blue fescue grasses are easily pulled apart to make more plants.

Oriental poppies and hollyhocks have long tap roots so cannot be divided successfully or moved.

They are easy to start from seed. Plants with one woody, stem such as lavender, cannot be divided.

Most ornamental grasses have dense root systems so it is easiest to divide the root ball with a sharp shovel while it is still in the ground.

This also works for large densely rooted clumps of perennials.

Two garden forks placed back to back in a perennial clump and then pulled away from each other, can be used in-ground to divide asters, yarrow, rudbeckia Goldsturm, etc.

Here are some tips for spring clean-up.

All perennials that re-grow from their roots can be cut back now.

Evergreen spring bloomers will bloom on last year’s growth so wait until after bloom to give them a good haircut to promote tidy new growth.

Woody perennials such as lavender may be trimmed by no more than one-third at a time.

Ornamental grasses need to be cut back now to about three to four inches above ground.

Comb out the dead material in the evergreen grasses, blue oat and blue fescue, or trim them into a rounded shape taking care not to cut into the central crown.


This spring, I will be teaching the Introduction to the Seven Principles of Xeriscape class on three Thursday dates: March 29 and April 5; April 12 and 19; and April 26 and May 3. Information and registration details are on the Classes page of the OXA website.