Early Season Rhododendrons

This past week has brought forth blooms on the first early rhododendrons of the season.  We have nearly 130 different species and/or hybrids of rhododendrons in the Garden.  The earliest usually begin in early May with the latest blooming into late July. Rhododendron fall into four main groups: deciduous azaleas, evergreen azaleas, lepidote rhododendrons and elepidote rhododendrons (azaleas are actually a type of rhododendron).

                                    A view of the Rhododendron Dell on May 28, 2010.

The main feature that separates azaleas from 'rhododendrons' is the number of stamens (the male parts); azaleas generally have 5 stamens while 'rhododendrons' have 10.  It is generally difficult to grow evergreen azaleas in Newfoundland.  Deciduous azaleas are generally easy but their main season of bloom won't be until mid-late June.

Lepidote and elepidote rhododendrons are the evergreen rhododendrons most of us recognize.  The so called 'dwarf-flowered' rhododendrons i.e. those with clusters of small flowers, are mostly from the lepidote group.  Another characteristic of this group is small leaves with tiny scales on the leaves, especially the undersides (easily seen with a magnifying glass).  The 'PJM' rhododendrons are a typical example of lepidote group.  We have several rhododendrons from this group currently in bloom including 'Madison Snow', 'PJM' and 'Isola Bella'.

The standard large-flowered rhododendrons are from the elepidote group.  These rhododendrons have no scales on their leaves although in some species/hybrids, they can have a fuzzy coating of short hairs.  These generally flower later than the lepidote group but a few are currently blooming nonetheless.  It should be noted that you cannot create hybrids between these four groups of rhododendrons.  For example, you cannot cross an deciduous azalea to a lepidote rhododendron.  Elepidote rhododendrons currently blooming in the Garden are 'Carmen', 'Frilled Ivory' and 'Elviira'.

So drop by the Garden this week to see the first rhododendrons of the season!

Plant of the Week May 26, 2010 - Erythronium 'White Beauty'

This white-flowered trout lily lives up to its name of 'White Beauty'.  Few spring bulbs are as elegant as trout lilies.  Not only are the flowers exquisite, but the foliage is also very attractive, being green with brown mottling.  This trout lily is of hybrid origin.  The tooth-shaped bulbs are planted in the fall in the same manner as tulips and daffodils.  The leaves emerge shortly after the snow melts with flowers starting in mid-May and continuing into early June.  By late July, the leaves have withered and the plant remains hidden until next spring.  In the wild they grow in dappled woodlands so in the garden, an organic-rich soil in part-shade is ideal.  This trout lily is available from specialty nurseries in the fall.  A lovely yellow-flowered version is called 'Pagoda'.  'White Beauty' is located in our Woodland Bed and the Rhododendron Dell.

Plant of the Week May 19 - Pulsatilla vulgaris

Finally a day of sun and the pasqueflowers (Pulsatilla vulgaris) really responded!  This species never fails to delight the gardener in spring.  Our first pasqueflowers open in late April but with the large number we have, they will continue to bloom into mid-June.  After that, you get the beautiful silky seedheads which are nearly as attractive.  This species has flowers which may be white, shapes of pink or purple and nearly red.

Pasqueflowers are generally easy to grow.  They simply require full sun and a well-drained soil.  They benefit from a yearly dusting of lime.  While in bloom, they will reach 20-30 cm but the flower stalks can reach to 45 cm when seeds are produced.  They resent disturbance so plant them where they will stay and like peonies, they will get better every year.  Most nurseries sell these but you can grow them from seed.  Seeds require a cold period (to simulate winter) of 8 weeks and the 'tails' are best removed from the seed.  They usually take 2 years to reach blooming size.

Highlights during the week of May 10-17, 2010

May 17 marked the first appearance of ducklings at Oxen Pond...will more broods appear?  Guess the next few days will tell!

Last Friday (May 14) we had a few hours of wet snow before it turned to rain.  Here are a couple of pictures of snow-covered  flowers...poor things!

Meanwhile, in the greenhouse where we are growing our annuals for the coming summer, the aphid, fungus gnat and soft scale have peaked in population with all the tender food available to them!  We avoid using nasty chemicals so each May we introduce biological controls. We use aphid midge and ladybugs to control the aphid populatiosn while a nematode is used to help control the fungus gnats. These biological controls were released last week.

A reminder that we have a few upcoming events.  On Saturday May 22 at 2:00 pm there is a free public lecture on 'Beware the Giant Hogweed'.  Giant hogweed is among the most recent alien invasive species to appear in St. John's.  Some consider this the most toxic plant in the world!  Come along and learn the potential problems caused by this newest invasive.

On Thursday May 27 at 6:30pm there will be an edible plant walk with a concentration on edible spring shoots.  There is a fee for this walk and registration is required.  Call the Garden at 737-8590 for more details or visit our website www.mun.ca/botgarden

Finally, on the weekend of May 29-30, the Newfoundland Horticultural Society will host their annual spring flower display.  Come along and see which spring flowers members are growing in their gardens.  Perhaps you will want to join the society after you see their display!

Plant Profile May 12 - Pulmonaria, aka Lungwort

The Garden has a modest collection of Pulmonaria selections, commonly known as lungwort or soldiers and sailors.  These plants have been grown in Newfoundland gardens for many years; in fact, a couple are even considered as heritage plants.  The wild types of Pulmonaria, of which there are 14 species, are native to Eurasia, growing in the dappled shade of deciduous woodlands or in sunny, alpine meadows.  They are members of the borage family, Boraginaceae.  Several of the species have flowers that change colour as they age, from pink to purple-blue.  This colour change may be a cue to pollinating insects to let them know which flowers are freshly open (full of nectar and currently unpollinated) versus those which are older blooms (already pollinated and with little nectar).  Several species have attractive white-spotted foliage.  Newer selections have leaves so heavily spotted that they are now almost entirely silvery in appearance.  Below are the main species growing in the Garden: P. officinalis, P. montana and P. angustifolia.

Below are some of the named cultivars we are growing at the Garden; 'Dora Bielefeld', 'P. longifolia 'Cevennensis', 'Spring Beauty' and 'Sissinghurt White'.

In regards to cultivation, Pulmonaria prefer a moist, rich soil.  They do not tolerate droughty conditions.  Full sun to part shade is best.  While they can tolerate considerable shade, their flowering will scant.  They are hardy throughout Newfoundland and south-central Labrador.  Blooming can start by early April and continue to nearly the end of June.  Many will start blooming with short stems (10-15cm) but the stems elongate throughout the blooming period until they reach about 30-45 cm. The leaves expand to their full size after blooming.  To maintain tidier plants, you should remove the faded flower stems.

Hellebore Season

If you haven't visited the Garden for the first time this year, now is the time to do so if you want to see Hellebores.  This group of plants is related to Buttercups (they belong to the Ranunculaceae).  However, they are far more fancy than the standard buttercup!  We have several species and hybrids; not all are open yet.  The main types open at the moment are Helleborus niger (white), H. X nigercors (white), H. orientalis hybrids (wine to cream) and H. odorus (yellow-green).  These are portrayed below, in the order noted.  If growing these in your garden, plant them in a deep, rich soil...like peonies, they improve with age and resent transplanting.  Full sun is probably best for peak performance but they will tolerate part shade and still put on a reasonable show.  Our first bloom in mid-April but they will bloom for several weeks yet.  As mentioned, we still have others not yet open.