Garden Notes

It's show time for the iris

iris
An iris freshened up by the morning dew. Photos by Susan Safford

By Abigail Higgins - June 7, 2007

Welcome to June and iris time! While the tall bearded group is undoubtedly the eye-catching member of the iris family, the Siberian iris hold much promise. More and showier cultivars appear in the trade all the time. The Siberian iris pictured here was a small, unlabeled plant with one or two turquoise-veined ruffled periwinkle blue flowers when I bought it about 20 years ago. I almost lost it a couple of times, but have now got two well-established clumps, about 25 inches tall. I have not come across another like it. Can anyone help ID it?

Other newer Siberian iris to look for, with an almost Japanese iris quality to the blooms, include 'Strawberry Fair,' a Morgan Award-winner with flaring crushed-grape falls and lighter, pinkish standards, and 'Steve,' with intense blue-violet flaring falls and lax medium sky blue standards and styles, a 27-inch tall cultivar I love having in my garden. A couple of others that I like to keep an eye out for: 'Roaring Jelly,' a strange name for a flared and ruffled raspberry/purple Morgan-Woods Medal-winner with lavender standards; and 'Over in Gloryland,' a deep blue-purple Morgan-Woods Medal-winner with a round, ruffled form.

My present white Siberian iris is an old-fashioned, small-flowered type of about 27 inches, very demure. Much as I like the recent white introductions, such as 'Gull's Wing' and 'White Swirl' with their showier flowers, they are mostly quite tall, around 36 inches. When I add another white Siberian, I am holding out for 'Mairi's Wedding,' at 24 inches.

Before getting carried away citing cultivars, let me mention the bonus that Siberian iris bring to the garden: their foliage. Long after the flowers have been deadheaded - do this, as Siberians are good seeders - their clumps of slender grass-like leaves function as vertical accents and provide movement, like ornamental grasses, in the garden.

Rhododendron
Rhododendron 'Bali,' R, and in the background, roseum elegans.

Patience pays off

I have finally witnessed the long-awaited blossoming of a flowering shrub I planted in 1987. The small plant of Rhododendron 'Bali,' a Leach hybrid in a one-gallon nursery pot, has suffered misfortunes and setbacks, many of them deer-related, between then and now. It is so exciting after the long wait to see the deep rose pink buds emerge through the bud scales and finally turn into trusses of pink and yellow flowers. Many gardeners experience the tantalizing, baited breath "will it/won't it;" it is our unique, exquisite torture.

Rhododendron hybridizers, including the late Mr. Leach, have developed many compact rhododendron hybrids, such as 'Bali,' for use on smaller properties. Plants tend to be wider than they are tall, and to top out at four or five feet. Mine is now about five feet by five feet. The flowers are clear baby pink with yellowish throats.

Not that I am disparaging the old standbys like the Dexter hybrids, R. roseum elegans and R. catawbiense alba (one of my favorites), but not everyone can own a rhododendron if it is going to become as big as a house. Colors too have taken off in directions undreamed of in older strains of rhododendrons, due to infusions of additional genetic material to the hybridizing mix.

If you are a tree, it's a good time to be a conifer - the fall cankerworm (Alsophila pometaria) and its kindred inchworms like to forage on deciduous tree leaves. Looking like the set for a creepy horror movie, it is a case of Life imitating Art on my road. It leads through an eerie forest of beech and oak, ghostly grey where it should be green, leaves skeletonized and branches draped with eerie curtains of caterpillar webbing dusted with pollen. It is surreal and disturbing, but something to be noted for the next Halloween Haunted House.

Yet we must remind ourselves that all trees and woodlands are continually in a state of growth and decline - much as we are, too - the agents of which include caterpillars, other insects, bacterial and fungal diseases, and wind and weather. Heartbreaking and harsh as it is to watch large trees reel from the attack, this is but one part of the cycle of forest growth and renewal.

Big trees most vulnerable

The worst-affected trees are sometimes the largest ones, called "wolf trees" by foresters for the space and resources that they demand in a woodland ecosystem. Large old trees have a high proportion of brittle wood and unlike younger trees lack the vigor to rebound: they are thus easily knocked off when their ecological context changes.

At my place I have sprayed some small plants - roses, recently planted witch-hazels, and viburnums - with Bacillus thuringiensis, which mostly seems to protect them. The rest of the woods is too extensive to concern myself with, except in a philosophical way. Why are some trees and saplings passed over, with hardly a chewed leaf?

A reader recently asked about woody gall-like growths on eastern red cedars (Juniperus virginiana). These are the fruiting bodies of the cedar rust organism, which spends alternate years on members of the Rosaceae family. During rainy spells, gelatinous orange tentacles emerge from the fruiting bodies. When dry, the fruiting bodies, which become about the size of a beach plum, are woody brown knobs engulfing a stem.

According to the Plant Clinic web site of Cornell University, http://plantclinic.cornell.edu/FactSheets/cedar-applerust/cedar-applerust.htm, "Cedar-apple rust is just one of several similar fungal diseases which could be broadly classified as Juniper-Rosaceous rusts. All of these rusts have very similar disease cycles but differ in exactly which juniper and rosaceous species they infect. The fungus spends part of its life cycle on a juniper host and part on a host in the rose family. It requires both hosts to complete its life cycle. All of these rust diseases are caused by species in the genus Gymnosporangium. Cedar-apple rust is caused by the fungus known as Gymnosporangium juniperi-virginianae....

"Examples of juniper hosts include eastern red cedar (Juniperus scopulorum), some prostrate junipers, and Chinese juniper. Examples of rosaceous hosts are apple, crabapple, hawthorn, quince, serviceberry, and pear. Some apple varieties are highly susceptible to cedar-apple rust, with both direct fruit infection and defoliation of infected leaves.

"Symptoms on the juniper hosts can include a swelling of the woody tissue and gall-like growth that may enlarge over time.... On leaves, lesions may be found on the surface or underside of the leaves depending on the spore stage present. These lesions often also have that bright orange coloration which is very distinct." Please go the site for the complete text.

This is a wonderful time to study the collections at the Polly Hill Arboretum. Next Tuesday a workshop in Observing and Drawing the Landscape is scheduled and the following Saturday is the Arboretum's Summer Solstice Celebration. Please call 508-693-9426 or go to www.pollyhillarboretum.org for more information.