Here in the northeast, mid spring teases us with periods of warm sunny days, tempting us to go out and buy the colorful annuals and tropical perennials stocked in local greenhouses. We forget that we may well get several more chilly nights. Perhaps frost is unlikely, but the soil temperature is going to remain too cold for the heat lovers until nights stay above 55 degrees F. If you plant these warm weather gems too soon, you will most assuredly stunt their growth.
The old timers always said to wait until Memorial Day to plant tomatoes and annuals, and for good reason. Only last year, many of us experienced a cool wet June, and many a northern gardener lamented how poorly Coleus, Colocasia and Cannas performed.
The best selection of Woodland Phlox, in our opinion, is this lovely cultivar introduced by Bill Cullina, of Coastal Maine Botanical Garden. Abundant deep sky blue flowers on 12″ stems perfume the May garden, and when planted en masse create ethereal drifts. It makes an excellent companion for woodland poppies and late blooming narcissus
‘Blue Moon’ grows best in light shade in a rich humusy soil that is moist yet well drained, forming clumps 2-3′ across. After the blossoms fade, cut back the spent flowering stems for a neater appearance. It is hardy in zone 4-8.
Gardeners in northern climates have been disappointed by Hydrangea macrophylla in the past….lots of healthy foliage, but few or no blossoms. This recent introduction of Mophead Hydrangea truly blooms on both old and new wood, and is being marketed as ‘Forever and Ever Red Sensation’ ( Tra-la-la…those clever marketers read a lot of fairy tales).
What you really need to know is that this vigorous selection produces lots of blooms on new growth, making it a great candidate for colder zone 5 and 6 gardens. In hot climates the large trusses of blossoms will be in softer shades of rosy pink when grown in neutral to slightly alkaline soil. Colder temperatures will cause the flower color to deeper red shades. If your garden soil happens to be more acidic, ‘Red Sensation’ will change color and thus need a new name, as it will take on bluer tones. The flowers age to smoky violet. Stems and fall foliage color have a dark burgundy cast.
‘Red Sensation’ grow 2-3′ tall and 3-4’wide, and require full sun or partial shade. Hydrangea macrophylla appreciate a moist, rich and fertile soil. May we suggest combining ‘Red Sensation’ with the always attractive Periscaria ‘Golden Arrow’?
Hydrangea paniculata ‘Limelight’ blooms on new growth
Even seasoned gardeners seem to be confused as to when to prune Hydrangea.
Begin by identifying which Hydrangea species you are growing, to determine whether it will bloom on new growth or on old wood (last year’s stalks). The species arborescens, paniculata and some newer forms of macrophylla bloom on new wood. All the Hydrangea macrophylla (Mophead and Lacecap types) and quercifolia (Oakleaf) bloom on old wood, as long as there isn’t winter damage. Next year?s blossoms are set on the upper portion of the woody stalks in late summer and fall. H. macrophylla selections should not be pruned until after the plants have leafed out. In late spring, prune out or tip back any dead wood for a clean appearance.
The hardiest and most foolproof of all the Hydrangea are the paniculata group (Pee Gee types) and the arborescens group (Smooth Hydrangea). Both of these species can be cut within inches of the ground each spring if you want to control the size of your plants. They stalks can always be thinned to improve plant shape, and there is no harm to next year’s display if you want to cut long stemmed bouquets in summer and fall.
There are a lot of new Hydrangea macrophylla selections on the market, including ‘Double Expressions’, ‘Red Sensation’, ‘Let’s Dance Starlight’, and ‘Endless Summer’ that bloom on old and new wood. The blossoms appearing on old growth will display in early summer, while the flowers that form on new growth will appear later in August and September, for a long continuous display. If you live in the colder parts of zone 6 or zone 5, you may get too much winterkill for blossoms on the old growth, but you will still be able to enjoy a late summer through fall display.
What has spring time blue flowers, grows 4-6″ tall, spreads by creeping runners, thrives in partial shade or shade in moist or drier soil? Meehania cordata, commonly known as Meehan’s Mint! This versatile and underused Northeast native is a good substitute groundcover for Lamium and Ajuga. It blooms in May and June with violet blue lipped tubular blossoms and would make a lovely underplanting for golden leaved Hosta and Hakonechloa (Japanese Forest Grass).
Although it is especially vigorous in moist soil, and would be a good choice for carpeting along a pond or stream, it will also grow well but more slowly in drier spots. It is hardy in zones 5-8 and would be a welcomed addition to a wildflower garden.
Should you lime your garden?
Here in the northeast, we seldom consider the effects of acid rain anymore. Since most public water departments deliver water with a neutral ph, the effects of acid rain have been largely neutralized in landscapes that use public water. Still, we cant be certain of the soil pH unless we periodically test it. it is a good idea to purchase soil pH testers, either online or at a local garden centers.
Be on the lookout…there may be treasure in your garden.
During your spring cleanup, you will no doubt uncover all kinds of delightful signs of life: the healthy shoots of perennials, dozens of tiny seedlings or wiggly earthworms under fallen leaves. One treasure you should be on the lookout for, and not mistake as something bad is the over wintering egg case of Praying Mantes (or Mantids). These pale tan Styrofoam looking sacs are attached in the crotches and on the undersides of bare branches. In late spring they will begin to split, upon which a hundred or more tiny translucent Praying Mantes will unfurl and march away to devour a wide variety of your most irritating garden pests. We were absolutely delighted to learn that they voraciously eat grasshoppers, which are a nuisance we’ve had difficulty with in the past.
The Praying Mantis is a most fascinating insect to observe in the garden. They sit motionless in the garden waiting for their prey to pass by. And yes, it is true that the females practice sexual cannibalism, (but not always, we’re told). Often the male is just not thinking straight when he has copulation on his mind and surprises the female as she sits motionless. Her first reaction is to grab hold and bite off his head (she needs the extra protein for pregnancy!). The male is able to fulfill his mission nonetheless and we hear he dies happily ever after.
So many of the earliest spring bloomers are diminutive in size, and invite you to kneel or even lie on your belly for the best viewing. Blooming with the early Crocus, the lovely and demure Iris ‘Katharine Hodgkin’ first appears as a pale yellow-green shoot, and then begins to unfurl to display falls and standards in the most ethereal shade of pale aqua etched with baby blue. Pastel orange-yellow markings accent the falls, and as her flower ages, ‘Katharine Hodgkin’ fades to delicious shades of blue-gray.
Although it is often sold as I. reticulata, Iris ‘Katharine Hodgkin’ is in fact a cross between 2 species, I. histroides, native to Turkey and I. winogradowii native to the Caucasus. She is a hardy soul, surviving in zones 4-9, and grows 4-8″ tall, preferring a well drained sunny situation that gets adequate moisture in late winter and dryness in summer. Planting and dividing is best done in the fall, but mark then spot, because she goes dormant in early summer.
Tending to Hellebores in March
One of the first things we tackle in the garden is raking up windblown leaves that have accumulated around the crowns of the early blooming Lenten Roses (Helleborus orientalis hybrids) and removing last year’s tarnished foliage, which may harbor pesky Botrytis spores.
As you cleanup the decaying growth, you may be fortunate to discover dozens of tiny seedlings at the plant’s base (of course that’s if the Hellebore bloomed well for you last year). These seedlings may be variable in color, especially if you’re growing a hybrid selection or more than one variety. You can always leave them undisturbed, and a few will eventually establish in situ or you can very gently lift the delicate seedlings and transplant them into small pots using a well drained potting soil. After a few months they will have put on enough growth for transplanting to other spots in your garden.
There are rare colors in the plant world, and black is certainly one of them. This new selection of Lenten Rose, from the hybridizing efforts of Ernie and Marietta O’Byrne, is one of the darkest shades we’ve seen. New growth emerges in early March here in New England, gradually sending forth flowering shoots as kinder weather warms the earth. The nodding single rose shaped flowers begin to fade in early May, after which the swollen ovules will burst, dispersing the ripened seed. Seed most likely will not germinate until the following spring, and the seedlings will likely differ in color from the parent plant, as this is a hybrid. New foliage will continue to develop as the flowers fade and the handsome leathery leaves persist through the winter.
Hellebores appreciate being grown in a partially shaded, well drained, fertile, slightly alkaline soil (pH of 7-6). Individual plants usually grow 18-20″ tall, forming sizable clumps over the years, and will withstand temperatures to -20 degrees F.