Seasonal Pruning

The vernal equinox is really more significant for meteorologists than it is for gardeners. Some plants respond to changes in day length, of course, but they don’t perform differently merely because days and nights are equal in duration.

Still, the vernal equinox (March 19, 2016) is a useful marker for the change from winter to spring.

As the world experiences climate change, scientists who study the seasons (phenologists) are generating more interesting reports about bud break, flower opening, insect emergence, animal migrations and other seasonal phenomena.

We are already witnessing changes in our gardens: for example, my lilacs are blooming earlier than they have in previous years. Lilacs (Syringa vulgaris) typically require a significant chill during the winter months, but decades ago, Walter Lammerts, working at a southern California nursery now known as Descano Gardens, developed three low-chill lilac hybrids: ‘Lavender Lady’, ‘California Rose’ and ‘Angel White’ (pictured). Gardeners in the Monterey Bay area and similar climates can grow Descanso hybrid lilacs and enjoy their fragrance.

Lilac 'Angel White'

Lilac ‘Angel White’

At the same time, my salvias are fading noticeably, earlier than I usually see.

These two garden favorites have markedly different pruning requirements. The lilacs bloom on new wood, so they should be pruned soon after the blossoms fade, before new buds form. This work should be done before June.

Another important maintenance issue for lilacs manages their strong desire to spread through underground runners. When allowed to roam for a few years, a healthy lilac will form a thicket. This may be desirable, depending on the shrub’s location within the garden, but containment might be appropriate. Accomplish this by the straightforward approach of excavating and cutting off the runner that has created the unwanted new growth.

By contrast, salvias can be cut back to about six inches above the ground in early spring, as new growth appears at the plant’s base. Such renewal pruning cleans away the old growth and stimulates vigorous new growth on these garden standbys. The right time for this work will occur in about one month. It is OK to prune earlier before the new growth is evident, but the ideal timing will shorten the least decorative period for your salvias.

A friend, busy with other priorities, saw the traditional season for rose pruning come and go this year, and now asks if she should prune her roses late, or let them go until next year.

The general rule for roses is to prune during the winter months, when the plants are dormant. Still, the popular repeat-blooming hybrid tea roses should be cut back as blossoms fade during the summer months. According to David Austin Roses, this approach will stimulate blossoming and support maintenance of a desirable rounded shape for the plant.

If a missed winter pruning has allowed a rose to compromise its overall shape, the gardener’s strategy should include summer pruning, cutting back stems after blooms fade with shaping the plant in mind, as well as encouraging new growth.

Pruning can be a challenging task for the gardener because of differences in best practices for individual genera. A good pruning book can help to reduce uncertainty, put the gardener in control and make the process easier and ultimately creative.

Enjoy your garden and keep your pruning shears clean and sharp.

Send pruning questions to Tom Karwin

 

A Not-to-Miss Event

As we enjoy the final days of winter, warmly, we begin thoughts of the arrival of spring and the reemergence of our gardens. With exquisite timing, the annual San Francisco Flower & Garden Show brings the season into focus and offers an unparalleled array of inspiration, information and products to help avid gardeners to launch the year’s gardening activities.

The SF Show began over thirty years ago as a fundraiser for the San Francisco Friends of Recreation and Parks, and soon evolved into a commercial event that features landscape designers, speakers on numerous topics in gardening, and exhibitors of plants and a wide range of garden products.

The Show ranks as one of the nation’s three largest annual events devoted to gardening and landscaping. The others are the Northwest Flower & Garden Show, which was held in mid-February in Seattle, and the Philadelphia Flower Show, which will be held March 5–13. Since 1829, the Philadelphia Horticultural Society has sponsored the Philadelphia Show as a fundraiser.

The world’s most significant competitor to these three garden shows is the Royal Horticultural Society’s Chelsea Flower Show, to be held May 24–28, 2016, at the Royal Botanical Gardens, Kew (near London).

This brief survey of major garden shows indicates that the SF Show amounts to a major event for gardeners of the west coast, and a great and accessible resource for gardeners of the Monterey Bay area.

This year’s SF Show will include 125 free seminars by gardening experts who have been selected as effective speakers. The seminar speakers and schedule is available on the SF Show’s website. The seminars are scheduled in five different stages within the San Mateo Event Center, so your attendance requires a little planning.

The Show also includes over 200 exhibitors in the Plant Market and The Marketplace. If you need any new plants or tools or garden art, you are likely to find them at the SF Show. One of the favorite exhibits is the large display by Succulent Gardens, from near Moss Landing. Early word is that this booth will be larger than ever, in response to enthusiastic collectors of succulent plants.

I will bring a couple mail order catalogs of garden plants and supplies for reference in evaluating prices at the SF Show. The prices are reasonable, I believe, but I always appreciate bargains.

The highlight for many visitors will be the Showcase Gardens, which will include nine full-size garden displays of the talents of landscape designers and craftsmen from northern California. The gardens often dazzle visitors by providing elaborate presentations of beautiful plants, stunning settings and unique concepts. These gardens present thematic designs that incorporate many ideas that can be adapted for your own garden. The designers of course will welcome new clients, and most will also be on hand to answers visitors’ question.

A day at the SF Show is really close by, not expensive, and an exceptional opportunity to bring gardening ideas and riches back home. It should be on your calendar.

If You Go

What: San Francisco Flower & Garden Show

When: March 16–20, 2016

Where: San Mateo Event Center

Info: http://sfgardenshow.com/