Category Archives: pruning grasses

Garden Tasks-Rain or Shine

Those of you who lived in the Santa Cruz mountains during the winter of 1982 remember it well. Following two days or torrential rains, a large section of hillside above Love Creek gave way. Thirty homes were destroyed and ten people were killed by the slide. The rainfall totaled 111 inches that year.

Rain gauge on 2/8/17 showing 99.99″ +10″ more as of 2/18/2017

During the winter of 1997 the San Lorenzo Water Department recorded 90 inches of rain. The department’s historical rainfall data goes back to 1888 and shows that during the winter of 1889 a whopping 124 inches of rain fell. This winter is one to rival the books with about 70-110 inches of rain falling so far depending where you live. We don’t aspire to break any records.

How does this much rainfall affect our gardens? If you have addressed drainage issues and are slowing, spreading and sinking all this water, congratulations. But what about the plants? Fortunately most plants are dormant or semi-dormant at this time of year. Even plants that don’t lose their leaves aren’t in growth mode yet. When a plant is actively growing either roots or new foliage it will suffer if the roots are soggy day after day. Fungal problems and root rot will take its toll on a plant. An extremely wet March or April is not a good thing.

We gardeners are the eternal optimists and hope that only gentle rains will fall through May. And during those lulls in the weather this is what I’m going to be doing over the next month.

California fuchsia – zauchneria californica

Prune fruit, nut, shade trees and deciduous vines like clematis. Cut back woody shrubs like Mexican bush sage, artemisia and butterfly bush to stimulate lush new growth. You can cut back these plants close to the ground. Don’t use this approach on lavender or ceanothus, though. Prune them lightly after blooming without cutting into bare wood.

Prune fuchsias back by a third and remove dead, crossing branches and interior twiggy growth. Container fuchsias can be cut back to the pot rim.

mophead hydrangeas in June

Cut back hydrangeas stems that bloomed last year and apply a soil acidifier if you want the flowers blue. Although sulfur is the traditional favorite for quickly acidifying soil it is not as kind to many beneficial soil microorganisms. Coffee grounds, pine needles, peat moss and cottonseed meal are better for your soil.

I’ll wait to prune back perennials that may have their new foliage damaged in a late frost. Already damaged foliage can protect a plant from further frost damage. Mid-March is the estimated date of last hard frost in our area. Or at least it used to be.

Don’t cut back grasses yet if you get frost in the area where they grow. Wait until mid-March. If you live where you rarely get frost go ahead and prune these plants back now. I’m going ahead and pruning California fuchsia, salvia ‘Bee’s Bliss’ and hummingbird sage now. They look terrible.

camellia sasanqua

Don’t prune spring flowering shrubs and trees like lilacs, flowering cherries, plums and crabapples, rhododendrons, azaleas, camellias, weigela or spirea until after they flower. You can cut some branches during flowering to bring in cuttings for bouquets.

I can tell that spring will soon be here as the flowering plum buds are showing color. Can’t tell from the weather report, though.

Pruning Ornamental Grasses

Who doesn’t love a garden filled with the movement and beauty of ornamental grasses especially during the fall? But how do you take care of them after the show is over for the season?

lomandraLomandra and NZ flax in mixed planting

When I recently received an email asking what to do with an ornamental grass that had already turned that soft tawny color I figured it was time to brush up on how to care for them. To prune or not to prune? That is the question.

Grasses are distinguished from other plant families by their growth habit. They grow upward from the base of a leaf or shoot and can regrow from the crown when cut back. True grasses generally have extensive root systems which help control erosion. There are other grass-like plants like chondropetalum, New Zealand flax, kangaroo paw and lomandra that resemble grasses in their growth habits and are often some of the best companions for interplanting with grasses.

Most grasses require little care, minimal fertilizer and only occasional grooming. Some flourish with just enough water to meet their needs while others need regular irrigation. Diseases and insect pests are rare and they are not attractive to deer. They have succeeded because of their adaptability and have evolved to suit almost every environment and climate on earth.

japanese_blood_grassJapanese Blood grass – small and goes dormant

Basically, grasses and grass-like plants fall into 4 different pruning types: Large or small types that go dormant and large or small types that stay evergreen.

Large grasses that go dormant such as miscanthus and calamagrostis are pruned yearly in late fall to late winter. It’s best to hold off on pruning as long as possible to preserve the winter interest and to provide food for birds. When they turn brown and start shedding it’s time to prune. Gather the blades together with a bungee cord or rope and cut down to 10 inches.

Small grasses that go dormant such as Japanese blood grass or fountain grass should be pruned yearly at the same time. Don’t cut them too close to the crown or you risk losing a few clumps. Cut those under 3 feet tall down to 3 inches and those that grow taller down to 6 inches.

guardsman_flaxThe Guardsman- NZ flax large & stays evergreen

Large, evergreen grass-like flax and cordyline can be pruned anytime to cleanup and resize but rejuvenation should be done mid-spring. When pruning to freshen up the foliage, select the most damaged leaves and cut them out at the base. If your plant is overgrown or suffered winter damage, prune severely in mid-spring cutting off all the foliage at the base. Tall cordyline varieties can be cut off a few feet from the ground and they will re-sprout below the cut or from the base.

Lastly, small evergreen grasses like carex, acorus, blue oat grass and blue fescue grass can be cleaned up in spring by putting on rubber gloves and combing through the grass. If this kind of cleanup isn’t enough you can reduce the height by two-thirds and in a couple of months they will look good again.