Summer Gardening and Flowering Plants

It is July, and though the solstice has passed, true summer is bookended by Independence Day and Labor Day, two months’ reward for seemingly six months of winter. Time is set aside for travel, vacation, summer camp, rest and relaxation. However, it is still a good time to garden, despite the old notion that it is too late in the season to plant. Indeed, this used to be true: when plants used to be field-grown for transplanting into a new garden, digging them up in the summer was risky business. Today’s plants, from trees, shrubs and vines to perennials, are grown in containers to make their transition into the ground practically stress-free. While it is true that summer additions to the garden must be watered, it’s equally true for those plants that were put in this past spring. (Please, don’t rely on lawn irrigation systems to do the job for you, unless you have a dedicated drip zone. Lawn irrigation does not water deeper-rooted plants sufficiently.)

The fireworks that light the skies on the Fourth are echoed in the flowers of summer, as July and August are the months of Coneflower (Echinacea) whose large bright daisies burst into dazzling and clean displays of traditional dusky pink (such as the standby cultivar ‘Ruby Star’,) but newer hybrids now offer shaggy mop-headed types such as the orange ‘Marmalade’ and ‘Hot Papaya’. ‘Evan Saul’ (Sundown™) evokes a desert sunset, with bright orange “petals” highlighted with rosy-purple. ‘Green Jewel’ offers cool light green “petals” – a unique color – surrounding a central green cone. Coneflowers are butterfly magnets, and their brown seed heads are prized by finches in late summer and beyond. They all do well in sun to part shade, and are drought-tolerant once established.

We are well-stocked with interesting and well-grown trees and shrubs. Our specimen Stewartia tree planted beside the barn has been flowering since June 20, and is just halfway done blooming, an inspiration for the smaller ones we have ready for planting. Summer-blooming azaleas are hardy, colorful and fragrant, and are superb for planting near a deck, patio or pool, where their sweet scent may be enjoyed in the day or evening. Several varieties are offered, and are in flower now. Buddleias (Butterfly Bushes) are budded and will be opening soon, as will the many types of Clethra (Summersweet) that we carry.

Ornamental grasses are now coming into their own, and will only continue to get bigger and better through the season. Plant them now to enjoy through the fall, as most types need the warm soils of summer to become established before winter.

Astilbe at The Mixed Border

And for the shadier gardens, our Hostas are spectacular, as always. We have on hand over a hundred varieties, from tiny-leaved miniatures such as ‘Baby Booties’ to ‘Empress Wu’, the largest Hosta to date, and with a wide choice in leaf colors and patterns of variegation. Astilbes are coming into flower, and we have a good selection of perennials, wildflowers and ferns for shade.

We welcome your visit.

Nursery Hours, July to September:

Monday: 9:00 am to 5:00 pm
 Thursday through Saturday: 9:00 am to 5:00 pm

Sunday: 10:00 am to 3:00 pm

We are closed on Tuesdays and Wednesdays, except by prior arrangement.

Please note that in the event of dangerous weather (such as thunderstorms or extreme heat) we may close earlier than scheduled, for everyone’s sake. Please call ahead (603-882-5538) if bad weather is forecast on the day of your visit.

The Best Hardy Plants for New England

Despite the recent snowstorm, our thoughts have been turning to spring which, according to the calendar, arrives on March 20. True spring weather usually takes a while to catch up to the Equinox, so it will be April at least before the ground is soft and dry enough to plant. Still, just before the snow fell, our Snowdrops were in full flower under the beech tree, and the fat budded blooms of Hellebores had already popped through the unfrozen soil. Once the snow melts, they will resume their awakening to flower in early spring, as they always do. Exotic witch hazels (not the late fall-blooming natives) have been in flower since early February, uncoiling their gold, yellow or orange ribbons on warm days, and retracting them at night. Bringing their cut branches into the house persuades them to release their pleasing perfume.

While we can only enjoy (or imagine) these garden delights (Winter flowers? In New Hampshire? Yes, they are possible, and easy) -- it’s not too soon to start planning.

Let’s face it, choosing ornamental plants can be a daunting task for new homeowners and otherwise inexperienced gardeners looking to landscape their yards. For some, a trip to a well-stocked nursery displaying a wide selection of plants can be as confusing as traveling to another country where people speak a different language and whose culture is unfamiliar. Questions of “Is it hardy?” “Will it do well in my yard?” “How much care do I have to give it?” immediately come to mind. It’s no wonder that one often sees the same plants repeated from one house to another, as though each garden was painted from a common palette. Yews and rhododendrons, arborvitae and azaleas, burning bushes and junipers dominate the planted landscapes of New England, because it’s easiest to repeat what is known.

But repetition isn’t always the best way, especially when repeating mistakes. Most of the more familiar plant choices mentioned above grow too large for the average “foundation” planting, and without regular pruning (which is typically more akin to hacking,) will soon cover up first-floor windows and grow over the walkways. And relying on a limited plant palette leads to boringly similar yards.

Better nurseries will have well-trained staff to assist in the process of selecting the right plant for the location, as well as helpful signage and tags. Experienced garden designers are familiar with a much broader range of plants, and know which will not only do best, but also perform and look well with little maintenance, and will arrange them in a distinctive fashion.

Another resource for New England gardeners is to seek out the list of Cary Award-winning plants. The Cary Award program (www.CaryAward.org, a non-profit entity established and administered by the Worcester County Horticultural Society) is bestowed upon hardy woody plants that meet certain criteria: they must be hardy to at least 2 of New England’s Hardiness Zones (but are generally hardy to at least Zone 5 if not colder;) they must offer more than a single season of beauty with an emphasis on having good winter interest; they must have qualities of sustainability (i.e., be easy to grow, not require chemical pest management, and not represent a threat to native flora;) and they must be readily available. Some of them are “problem solving” plants for difficult areas.

This year’s winners of the Cary Award include a low-maintenance rose – Rosa ‘Knock Out’ and the native Yucca filamentosa or Adams Needle, joining 43 trees, shrubs, vines and ground covers that have previously been honored since 1997. A complete list, including information about and photos of individual winners can be found at www.caryaward.org. (Full disclosure: I have been a member of the Cary Award selection committee for many years as one of New Hampshire’s two representatives. Each New England state is similarly represented by professional horticulturists.) We have named future selections up to 2016, with each year’s winners announced at the appropriate time, and are working on plants to nominate and name for 2017 and beyond. Nominations may be made by anybody, and are not limited to those of the committee.

When considering which plants to replace those that may have been damaged in last year’s Halloween snowstorm, or which to choose to enhance your home or garden, be sure to start with Cary Award winners – proven for hardiness, reliability, ease and extended beauty.

Native Plants and Others

It’s common knowledge that the state tree of New Hampshire is the white or paper birch (Betula papyrifera) while its state flower is the purple lilac (Syringa vulgaris.) The birch, venerated for its white bark and flexible but resilient “bend but don’t break” manner, is a hardy native, and one which stands out year round. The lilac, on the other hand, is decidedly “not from around here”, but rather an exotic species of southeastern European origin, having been brought by early settlers to Portsmouth, NH and then distributed far and wide. Despite its having existed in North America for over 300 years, it will never be a native, even though it has become naturalized (a term which is applied to both plants and people. In a way, most of us are all naturalized citizens.)  Its presence is often only revealed in spring, when its fragrant and familiar blossoms betray its position, one which once probably began in the dooryard of a colonial home long gone, its cellar hole a vestige of time past, as suggested by Robert Frost (another non-native – he was born in California) writes in his poem “Directive”:

...for the house that is no more a house,

But only a belilaced cellar hole,

Now slowly closing like a dent in dough. 

Lilacs, courtesy of April Walker

I compare the birch and lilac because they represent more than the official state flower and tree. They also illustrate the problem with declaring natives more suitable than exotics in the landscape.

Native plants (the definition of which varies, but typically used to describe those which were here before European colonization – but that is also problematic, as there were trees growing millions of years ago on this continent which are only found today in Asia) are thought to be better choices for the landscape, requiring less water and other care than exotics. There are plenty of Japanese Barberries, Norway Maples, Burning Bushes, and other plants which have escaped from cultivation and are now considered invasive species to disprove the thesis.

Let me state that I am a firm believer in the value of native plants, appreciate their beauty and status in the wild, and am a dedicated advocate for their use in managed landscapes whenever appropriate. Given the choice between a native and an exotic, I will typically opt for the former. However, as shown in the above example, exotics also have their place, so long as they don’t spread so aggressively as to displace native plants which have evolved along with native wildlife to their mutual benefit.

Drive down a country road when lilacs are in bloom, and you are likely to see lilacs growing as described by Frost, Whitman and others, an enduring and endearing shrub which has become an archetype many homeowners can’t live without in their gardens, despite its brief display. The white birch, on the other hand, is easy to spot at any time, but much harder to grow. It prefers cool, moist soil, and suffers when affected by drought. Indeed, its major nemesis is an insect called the Bronze Birch Borer which is able to detect a chemical signal emitted by birches under stress, and in which she lays her eggs which hatch and spell doom for the tree.

A similar example can be found with dogwoods: the native flowering dogwood (Cornus florida) is susceptible to another form of borer, as well as a destructive disease, when not grown under the right conditions. The exotic Kousa dogwood (Cornus kousa) is resistant to both, and is often the better choice. Hybrids between the 2 species (the so-called Rutgers types) have been produced which offer the best of both.

Clearly, the discussion of whether native plants are superior is complicated. Natives usually offer wildlife more value, and their presence in natural settings is critically important. However, it bears notice that natives may not always work well in managed landscapes, and appropriate choices may be found in plants which may not have originated here.

Azalea or Rhododendron?

Forsythias, those cheerful harbingers of spring (but certainly not the first woody plants to bloom) are completing their annual gaudy display, and as they fade into their seasonal greenness, our eyes fall upon the bright mauve-purple blossoms seemingly as common as Forsythia – the PJMs. These rugged evergreens with smallish oval-shaped leaves are thought of by many as azaleas, but they are not. They are Rhododendrons.

It is easy to understand the confusion, because they are related. All azaleas are Rhododendrons, but not all Rhododendrons are azaleas (they are botanically differentiated by the number of stamens each flower carries: azaleas have five, while Rhododendrons bear ten or more.) And azaleas are grouped within the genus Rhododendron, and part of the larger heath family which also includes heathers, blueberries and cranberries, mountain laurels, and more – all prefer cool, moist acidic soil, so mulches are always helpful (see my previous article.) Rhododendrons (not azaleas) can be divided into 2 categories: large-leaved and small-leaved types, and the PJM belongs to the latter group. Generally speaking, those with large leaves prefer some shade, although they flower better if given at least 1/2 day of sun, and the small-leaved Rhododendrons perform best in full sun, but tolerate some shade.

Those familiar with azaleas know them to bear bright red, pink, purple or white flowers on spreading bushes that remain semi-evergreen in the winter. These types perform better in more southerly locations, but can be found locally each spring when in bloom. They generally need careful siting to prevent the crisping of their foliage in our cold and dry winter air. Deciduous azaleas are far more reliable, and have a much greater range of flower color – from white to yellow, orange to red, but no blue or purple. And rather than having the narrow bloom times of the semi-evergreen varieties, by choosing different deciduous types, one can have flowers from April to August.

Rhododendron ‘PJM’ was hybridized in the 1930’s by the late Ed Mezitt of Weston Nurseries in Massachusetts, and he named it after the initial letters of his father, who founded the nursery. This fortuitous marriage of an Asian species and an American native has become the benchmark of hardy rhododendrons, and it is very hardy. It is also quite easy to grow, thriving in full sun to part shade. Its only downfall is soggy soil, as it leads to root rot. Indeed, its ease of growth has made it as common as lilac and forsythia in the northeast, and combines well with some Magnolias which bloom at the same time.

Because its purply color can be a bit jarring in the landscape, Ed Mezitt continued to breed rhododendrons in search of calmer pinks and whites, but also a true red (which he never achieved in his small-leaved hybrids, but came close with ‘Landmark’, one of my favorites.) The varieties ‘Olga Mezitt’ and ‘Aglo’ (Olga spelled backwards) are nearly as popular as the PJM, and bloom about a week or so later, nearly in concert with crabtrees. Their showy flowers are a clearer pink, but their habit is a bit more “open” than the denser ‘PJM’. These varieties, as well as many others including ‘PJM’ have deep green foliage that is aromatic when brushed against, and which turns dark bronze to mahogany when the colder weather arrives in the fall.

Mezitt’s breeding work also included azaleas, and he used the rich palette of deciduous species native to New England and the Northeast in his work, as well as a hardy semi-evergreen species from Korea. The deciduous hybrids are outstanding, because most bloom in early to mid-summer. (A future article will cover these superb “Summer Blooming Azaleas.”) Further reasons to grow these types: they are often sweetly fragrant, and many have vivid fall foliage, extending their season of beauty. Although his semi-evergreen introductions are less well-known (and hence not easy to find,) they generally perform better in central New England than those more commonly available, because that is where they were bred and tested.

Large-leaved Rhododendrons will soon be blooming in May. Although there are hundreds of varieties hardy for our area, most nurseries and garden centers stock relatively few. Because they are frequently used as “foundation plants”, it’s best to look for varieties which remain naturally compact, rather than dealing with green monsters which can quickly swallow up a window. Look for a discussion in an upcoming issue of some of the lesser-known varieties which I consider to be better in many respects from the traditional offerings.

Hazels and Hellebores – the Flowers of Early Spring

Winter can seem interminable to the New England gardener, with the possibility of snow from October to April. By March, we are desperate to see the inky brushstrokes of branches against the white sheet of snow become transformed into the verdant watercolor that is spring. We long for green. We long for flowers.


Hamamelis intermedia 'Pallida'

For those who think that Forsythias and crocuses are the floral harbingers of spring, they are late to the party. Witch Hazels (Hamamelis) have been blooming in our gardens since the end of February, and will continue for weeks to come. They are the earliest woody plants to bloom where they are hardy (USDA Zone 5). Although of exotic origin, they are related to our native Witch Hazel (Hamamelis virginiana), which unfurls its pale yellow ribbon-like petals in October and November.

The spring-bloomers are ornamentally superior to the native Witch Hazel. Their flowers are far showier, and hybridization has resulted in colors ranging from soft yellow to brassier tones, and even orangey-reds. Most are fragrant, adding to their charm, and an armload of branches brought into the house will scent the air with sweetness. The variety ‘Arnold’s Promise’ has long been my favorite, with its bright lemony-yellow blossoms.


Hamamelis intermedia 'Pallida' flowering with snow still on the ground

Whether in bloom or in size, these are not timid shrubs. They’ll flower dependably, beginning in late February or early March, even in the snow. Each year they’ll grow larger, eventually reaching twenty feet or more in height, with a wide spread. I think they are excellent choices for a sunny corner of the house, or at the edge of a woodland garden, as Witch Hazels can tolerate a little shade. Plant some Snowdrop bulbs (Galanthus) beneath one in the fall, and you will be rewarded with your own flower show each year.


Corylopsis spicata 'Golden Spring' in bloom

Forsythias can be troublesome shrubs, as they often grow ungainly without proper pruning. A better choice might be Winter Hazel (Corylopsis spicata), which as I write this in late March, is just coming into bloom. The flowers are a lovely shade of soft yellow, and are carried on stems that are much more elegant than the common Forsythia. Although reported to be hardy only to Zone 6, we have been growing Winter Hazel in our Zone 5 gardens for the past 20 years with little or no winter damage. The pleated, bluish-green leaves remain attractive all season. We have a chartreuse-foliaged one planted in our garden (C. spicata ‘Golden Spring’,) and hope to offer this variety for sale soon. All benefit from a little shade, especially in the afternoon.


Hellebore hybrid

Lenten Rose, or Hellebore (Helleborus), have long been appreciated in Europe for their early blooms that defy cold weather. Over recent years, they have gained a following in the US, and there has been much breeding work done to produce a virtual rainbow of colors and “doubled” flowers. Our Hellebores started to emerge from the ground once the snow melted, and a week of unusually mild weather has brought their flowering stalks to attention, while catching ours. If snow were to fall on them, it’s no matter, as they will patiently wait for it to melt and reveal their long-lasting blooms. Placing Hellebores under a deciduous tree or shrub will give them sun early in the season, and shade later. The foliage is leathery yet quite handsome, and effective all season. I like to clip off last year’s foliage in the early spring, to give room for the new shoots.


Helleborus 'Blue Lady'

It’s little wonder why these superb plants are rarely seen in gardens. Often, they have finished blooming before gardeners seeking springtime cheer are visiting nurseries – all the more reason to do some homework before making a plant purchase, rather than buying what’s in flower. To have four-season interest in your garden requires planning, and patience. To quote W. E. Johns, “One of the most delightful things about a garden is the anticipation it provides.”


Helleborus 'White Spotted Lady'