Author: Brad MacDonald

 

Ornamental pear trees are in full bloom across Nantucket this week.   These adaptable trees have been widely planted throughout the country.  They are disease resistant, with lustrous green leaves, and often have good fall color.  This time of year the entire canopy is filled with sprays of delicate white flowers.

There are many popular selections, each suitable for different situations.  Some common ones are listed below, with noteworthy characteristics.

 

 

• New Bradford (R)   An improvement on the ubiquitous ‘Bradford’ Considered to be hardier with superior foliage.  Reaches 35′ or more in height, conical in youth, becoming more broad with age.
• Aristocrat (R)  Distinguishable from other ornamental pears by its wavy -edged leaves.  This selection tends to maintain a strong central leader and grows to around 35′ tall and 16′ wide.
• Chanticleer (R) AKA ‘Select’, ‘Cleveland Select’, and ‘Stone Hill’  An upright pyramidal selection, still reaching 35′ tall, but slightly narrower than Aristocrat (R)
• ‘Trinity’ AKA ‘Sylvania’  Much more rounded selection reaching 30′ x 30′ in maturity.
• P. fauriei Korean Sun TM AKA ‘Westwood’  Compact rounded habit, only reaching 12′ – 15′ in height.  Red/Purple fall color.

 

Ornamental cherry trees provide a stunning show of flowers in Spring. Native to Japan, they are now grown across the northern hemisphere. They are impossible to miss when in full flower, especially as the petals drift to the ground during Spring breezes.

‘Okame’ tends to be the first to come into bloom on the island. But ‘Mount Fuji’ and ‘Autumnalis’ are also early. ‘Snofozam’ and ‘Akebono’ will be next. ‘Kwanzan’ is the last to bloom.

“Holy Cow! What is this crazy thing growing on my trees?” Great question! It’s not an alien space nut, but it definitely looks like one. The strange looking growths that appear on Cedar trees this time of year are caused by a fungus called Cedar apple rust. In order to complete its life cycle, the fungus causes swellings, or galls, on Cedar trees.

Most gardeners won’t notice the hard brown galls when they first appear in summer. They are still small, and often disguised by the lush needles at the tips of the branches. But they are difficult to overlook as they swell in spring, and later produce gelatinous orange tentacles during warm, wet weather.

The tentacles release spores into the air that infect apple trees. They germinate within a few minutes on the moist leaves. The infection does not travel within the tree, but causes orange spots to develop on the leaves. These lesions then produce more spores, that infect Cedars, and the cycle continues.

The disease does cause serious damage to the leaves of apple trees, and can completely defoliate even healthy trees. Trees that are repeatedly infected with cedar apple rust can decline, and fruit volume and quality often suffers.

Unfortunately, there is little the Nantucket gardener can do to prevent Cedar apple rust. Experts recommend planting apple trees five miles away from Cedars so that the life cycle cannot be completed. But we have Cedars growing on nearly every part of the island, so that’s just not possible. If you have Cedars, you can expect to see at least a few of these galls each year.

Because the branch tips beyond the gall will eventually die, there is no reason not to remove galls as you see them. Overall, Cedars are left unharmed by the gall, and will continue to thrive. The only way to stop the spores from infecting apple trees is with fungicides. The application of these products must be precisely timed to be effective. Nantucketers serious about producing high quality apples, should consider contacting a professional tree expert to take care of the applications.

This time of year, things can still seem a little bare in the landscape. Especially glancing at the garden from indoors. On warm days, it’s very rewarding to take a walk outside and look closely at the plants, as they break dormancy. Working around the Nursery last week I couldn’t help but be drawn to the Corylopsis.

Reaching 4-6′ tall and wide, Spike Winterhazel forms a tangled mass of crooked branches. Pendulous yellow flowers form on bare stems in April. As the flowers fade, leaves begin to appear in a shade of purple, maturing to blueish-green.

Think of Winterhazel as a cool alternative to ‘Harry Lauder’s Walking Stick’. Plant it as a focal point in your shady garden, or as a mass at the edge of a moist wooded area.

There are many types of Hydrangea grown here on the island. When it comes to pruning, it’s important to remember that different types of Hydrangea have different blooming characteristics. Hydrangea paniculata produces large, conical flowers on new wood in mid to late summer.

Objectives for pruning these shrubs are: Removing dead and damaged wood, removing congested pollards, keeping the plant an appropriate size for its location & stimulating flower production.

Follow these steps to prune an established Hydrangea paniculata multi-stem shrub (not a standard tree) while dormant:

1.Remove any dead or damaged wood. Starting at the tips of the branches where flowers were formed last year, cut back above pairs of buds until a clear ring of green tissue is evident. Entire branches can die back to their point of origin over the winter. Don’t let it upset you, just remove them as cleanly as possible at the base of the plant or where they meet a larger living branch. Remove any thin, brittle twigs as well; they will not be capable of supporting flowers.

2.Remove pollards. Pollards are formed by making pruning cuts at the same place every year. This causes congested areas of weak, spindly growth. If possible, make pruning cuts below the pollard just above the next set of beds, stimulating healthy buds to grow into strong branches.

3.Remove crossing or rubbing branches. Sometimes, we can’t fix every problem and still end up with a balanced shrub. But take the time to remove at least a few branches that grow horizontally toward the center – these branches will begin to rub and damage favorable, upright branches.

4.Prune for overall size and flower production. Cut back all young, strong, branches to within two buds of the main branch. Remember, flowers form at the tips of new wood that grows from the buds just below the cuts made during pruning. Some varieties can put on three or more feet in a single growing season, so observe last years cuts and how much growth occurred above them. Adjust the severity of your pruning accordingly.

Wisteria is one of the most beautiful, but rambunctious, vines planted in Nantucket gardens. Its pendulous flowers are a show stopper when they cascade from the leafless branches in late spring or early summer. But Wisteria has well-warranted reputation as a garden thug. Judicious pruning is essential in maintaining this vine.

Before beginning, it’s helpful to keep your objectives in mind: To remove dead or damaged wood; to remove excessive vegetative growth; to tie in young branches to fill areas that need coverage; to stimulate flower production close to the main framework.

Follow these steps to prune an established Wisteria while dormant:

1) Take a good look at the underlying structure of the vine. While pruning, its important to maintain a strong framework, so that when flowers form, they are evenly spaced all over the pergola or trellis that the vine is growing on.

2) Remove all lateral growth sprouting from the trunk that is not a part of the main framework. If grown on a pergola, the trunk is often maintained completely bare, with no lateral growth allowed to mature. These spindly stems will run along the ground, and root quickly. If any have already taken root, be sure to pull them up. The goal is to cultivate the upper portion of the vine that has been grafted onto the rootstock. Any growth that sprouts from below the swelling on the trunk where the graft was made will likely never flower, or even have the same characteristics as the scion.

3) Cut back young lateral branches, leaving only three or four buds. If there are bare areas of the support structure, tie in well placed laterals while pruning systematically across the canopy. Don’t hesitate to tip short spurs that were naturally formed during previous seasons. This method of pruning forces energy directly into the remaining few buds, causing them to form larger flowers that are held on short, strong spurs. The buds on the long, whippy growth from the previous season are not capable of producing flowers and will only form a tangled mass in the canopy of the vine. This makes it very difficult to do summer pruning later.

 

A lot of people consider March “Hate Month” here on the island. After a long, grey winter, year-round gardeners yearn for some color! Of course, there are many plants that thrive on Nantucket with winter color. The stems of Yellow and Red twig dogwood, Willow and High bush blueberry are beautiful. And plants that hold their fruit over the winter, like Winterberry, have great value in the winter landscape. But wouldn’t you just die for some flowers? Enter – Witchhazel!

The waxy petals of this winter-blooming shrub are a sight for sore eyes when they cover the branches of these versatile plants in February and March. The flowers range in color from clear yellow to deep amber and red, depending on the species and cultivar. The habit is also varied; some plants are more upright, with smooth branches, while others are much more arching or contorted. There are plants that will colonize to fill a large space, and others that fit into tighter spots, especially with some pruning. Hamamelis prefers moist, even soggy soils, but will perform as long as it has regular water in normal conditions. It can be sighted in full sun, but does very well in partial shade, as well.

An interesting alternative to Forsythia, tough as nails, and not bothered by insects or disease – Give Witchhazel a try. You’ll like it!

 

Commercially produced plants are grown to many specifications. Smaller plants are usually container grown, however large trees are generally grown in the field, dug, and then balled and burlapped (B&B). The standard way of comparing trees over 8 feet tall is called Caliper. For nursery-grown trees, this a measurement of trunk diameter, in inches, taken 6 inches from the rootball.

Trunk Caliper can be used to predict the overall size of tree, and the size of its root ball. Professional landscapers use this information to order trees when they can’t go out to the farm to see them in person.

The speed that trees reach salable size in the field varies between species. Also, different species require specific rootball volumes to transplant well. A tree with a 2″ caliper can be expected to have a rootball weighing around 400 lbs! If you are investing in a tree for your yard, speak to a professional landscaper who will be able to recommend what size you can handle and still meet your needs