Rhododendrons and Azaleas

RHODODENDRONS AND AZALEAS

The first rhododendron I came across was R. praecox growing in a large drift in a bed of pure leafmould. This was at Dawson Park in 1960 when the park was in its early years and was not much more than a playing field with a few interesting plants to relieve the boredom. I won’t ever forget my first two years apprenticeship training, digging drains all winter at Dawson.  The highlight of the year was when that rhododendron flowered and that only lasted a couple of weeks, but it must have made an impact on me as I have never been without my R. praecox. It is one of the first to flower usually in March or early April but only if there are no frosts to shrivel up the delicate mauve flowers.

The following year I was working at Camperdown Park where mature rhododendrons grew all over the place. Training trips in spring arranged for the apprentices by our tutor Walter Gilmore took us to Edinburgh Botanical Gardens and Crarae Gardens where both Rhodos and Azaleas are grown on a massive scale but to perfection. I was hooked for life. Parks training helped me understand the range from the tall varieties to the dwarf evergreens and the deciduous azaleas, and that first bed at Dawson growing in pure leafmould made me realise the importance of giving them the correct type of acidic soil.

Today we do not have to go too far to see them in all their glory growing in natural surroundings covering the whole spring season. The gardens at Glendoick are now world famous as the place to visit to see hundreds of different rhodos, azaleas, camellias and numerous other woodland plants growing in a natural setting of a Scottish glen complete with a burn and waterfalls.

History

No article on rhododendrons and azaleas would be complete without some reference to the massive contribution made by several generations of the Cox family.

In the early nineteenth century the Cox family started a textile business in Lochee. This was consolidated by four Cox brothers in 1841 and the factory at Camperdown Works was reputed to be the biggest jute factory in the world employing 5000 people. Alfred Cox bought Glendoick House and estate in 1899. His son Euan, educated at Rugby and Cambridge, got a taste for the good life while working in London and had little enthusiasm to return to the jute business in Dundee.

A chance meeting in London with the plant explorer Reginald Farrer led Euan to join him in his first plant collecting expedition to Burma in 1919. The trip was a great success and many new rhododendrons and other plants were introduced. Euan loved to write about the new plants being introduced from all over the world and founded a bookshop in London. However this got bombed during the war and Euan returned to Scotland to help run the family jute business. He started to develop the gardens around Glendoick with his new seedlings from his expedition. He also subscribed to other expeditions and received many new plant introductions. A nursery was started with new plants acquired from other collections. Then his son Peter started to go on plant collecting expeditions to Turkey, India then China in 1981. The garden at Glendoick expanded up the burn.

The rhododendron nursery was established in 1953 and the garden centre in 1973.

Peter’s son Kenneth has maintained the family traditions with 9 plant collecting expeditions and written many horticultural books. Peter and Kenneth have been breeding rhododendrons for over 50 years to produce plants suited to small gardens and the Scottish climate.

For the full and fascinating story of Glendoick, the Cox family, and their involvement with rhododendrons and plant exploration, check out the website at www.glendoick.com.

Types and varieties

Most Rhododendrons are evergreen but the Azaleas may be evergreen or deciduous. They come in all sizes from a few inches tall to small tree sizes given time. Many of the deciduous azaleas, eg A. luteum are scented. The flowering season normally runs from April to June, but changes due to weather pattern at the time, and there is always a few types that will flower early or later throughout the summer. R. praecox can flower in late March but the flowers are not frost hardy so can get wiped out in a bad year.

If you have a large garden you can indulge some of the taller growing varieties such as Cynthia, a vivid scarlet, Pink Pearl, or Horizon Monarch a yellow with red buds.

For smaller gardens try Nancy Evans, a deep yellow, or Elizabeth, a brilliant red that has been a favourite for years.

Azaleas tend to flower a bit later, but many have an exotic woodland scent and orange flowers such as Gibraltar. Klondyke is a brilliant yellow and there are numerous others in reds, pinks, mauves and white.

Dwarf evergreen azaleas (Japanese azaleas) may only grow a couple of feet or so after ten years, but they are perfect for mass planting for ground cover. They are also very easy to propagate from cuttings. Glendoick have bred numerous new varieties in colours including pink, purple, scarlet, white, orange and crimson.

Site soil and planting

Most Rhododendrons and azaleas flower better in full sun in Scotland as we don’t suffer too many very hot summers. They associate well as woodland fringe plants with a backdrop of birch, rowan, pine, spruce or if you wish a flowering tree choose a cherry or Eucryphia Rostrevor. However make sure they are not shaded by the canopy.

An acid soil is a must with all of these plants. Fortunately most soils in this area are naturally acidic, but may have been limed for previous crops. They like a free draining soil that can hold moisture. Soils can be improved by digging in plenty of leafmould, composted bark, garden compost, pine needles or peat. Acidity can be improved by using sulphur chips and a pre planting light dressing of sulphate of ammonia and sulphate of iron, but not after planting as they may scorch young leaves.

Plant rootballed plants in the dormant season, but containerised bushes can be planted at any time provided they are always kept moist. Do not plant deep and any mulch should only be quite shallow as the fine surface roots do not like getting buried.

Rhododendrons and azaleas do not need much feeding, so a light annual mulch will be quite enough.

Pests and diseases

Mildew may be a problem on a few varieties, (Elizabeth is prone) but can be controlled with a fungicide used for rose mildew.

Azalea leaf gall, exobasidium, can be a problem on the Japanese evergreen dwarf azaleas. Pick off and destroy any galls as soon as you see them.

Vine weevil adults cut notches around leaves and can girdle the stem just above ground level. They produce white grubs that eat the roots.

Lime induced chlorosis is only a problem where the soil is not acidic enough.

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Flaming June did happen this year

FLAMING JUNE DID HAPPEN THIS YEAR

The summer returned this year after three years of cool and wet weather following a very long and cold winter. That is the kind of normal weather I remember from childhood to youth, before global warming appeared and weather pattern became guesswork.

The garden plants have responded with strong healthy growth, a lot less pest and diseases, flowers in profusion and fruit crops to come, full of potential.

Some outdoor fuchsias never made it through the winter, hebes were lost as well as my Leptospermum Red Damask, however Fuchsia Mrs. Popple has sprouted from the base and will have its first flowers by the time you read this, despite the attention of the greenfly and frog hoppers, (cuckoo spit).

Always give apparently dead plants plenty of time after a hard winter to recover before you dig them out. Some years ago I had a 15 foot tall Cordyline australis the Torbay palm, that died after a very hard frost. It was cut back to ground level, but then 18 months later five new shoots appeared and it sprang back into life. A lesson was learnt. Eucalyptus can also be a bit tender when young though my twelve year old specimen has never looked better.

Robinia frisia, the false acacia, an excellent small tree with golden leaves suitable for domestic gardens lost a few branches but soon recovered. It needs good drainage at its feet to survive the winter, otherwise die back of shoots get infected with the coral spot fungus which can then spread to healthy wood.

This year it was the turn of my date palm, Phoenix canariensis, to die back to ground level after successfully growing outdoors in a sunny border for six years as a specimen dot plant in the middle of a flower bed. It got chopped back to ground level but I see it is trying to make a recovery.

The Flower Garden

Glorious colour abounds in herbaceous borders, rose beds, climbing roses, flowering shrubs and in tubs, hanging baskets and borders with summer bedding plants.

Dead heading to remove seed heads is a constant task with Rhododendrons, Azaleas, Himalayan blue poppies, Iceland poppies, and winter pansies who wont stop flowering. I have never known them to continue for so long so I keep feeding and watering them.

Seeds gathered from the Meconopsis, Himalayan blue poppy, and the Iceland Poppies will be sown this month. I hope the Iceland poppies will germinate fairly soon as they are to grow on for flowering next spring, but the Meconopsis will probably not germinate till next spring. Keep both of them moist, shaded and cool to assist good germination.

My bed of geraniums grown from cuttings every year is a mass of colour, but my other summer bedding plant the tuberous begonias have yet to put out their first flowers. They are looking very strong. I purchased a tray of fifty mixed double non stop tuberous begonias about 15 years ago. They flower reliably every summer then get dried off, and overwintered in a box in the garage,

They never let you down.

Excellent value for money.

The Fruit Garden

A funny year for fruit. I have been too busy on other activities, painting flowers, and running art classes, so I never got around to netting my strawberries to keep the birds from eating them. I never lost a single berry, yet the local blackie took a liking to my red currant bushes so these got the strawberry net for protection. I have not needed to net red currants for the last four years. Birds left them alone, but not this year.

The net has also been erected over my saskatoon patch as they are so favoured by the birds that they will even attempt to tunnel underneath the net if it is not buried around the edges.

The saskatoons, Amelanchier alnifolia, should be ready for picking mid July probably at the same time as my red currants, black currants and gooseberries.

This year I only have Autumn Bliss raspberries as my row of Glen Ample got infected by a root rot fungus which wiped them out. I think it was phytophthora but cannot be certain.

There replacement variety Cascade Delight will not bear any fruit till next year, (hopefully)

Apple trees are quite heavy with crop, but the natural June drop did some thinning for me. I then did a little bit more to space apples out so I get larger fruit.

My variety Fiesta has adopted a biennial fruiting attitude with only five apples on a young tree that gave me over forty last year.

I will cover fruit crops in greater depth next week.

The Scottish Crops Research Institute will be holding an event for those in the fruit industry on Thursday 15^th July at Invergowrie to showcase developments and trends in their breeding and research programmes. This cutting edge technology eventually filters down to gardener level as we benefit from the release of new fruit varieties with enhanced cropping potential, better flavour, more disease resistance, stronger vigour and acclimatised to Scottish growing condition.

The Allotment

Two rows of Beetroot Bolthardy germinated very well so they required a thinning to leave them about an inch apart. These will grow into lovely baby beet size before a further thinning to four to six inches for the main crop. Last year our beetroot was left in the ground unprotected until winter digging time in January and was still excellent. The cold winter did not do any harm. We use beetroot for soups mixed with potato, onion and a wee bit of orange rind, then finished off on the plate with some yoghurt or sour cream swirled into the surface. It is brilliant and most likely very healthy.

Leeks are another vegetable that are very easy and rewarding as they keep you supplied with fresh vegetables right through the winter till March, or April in a long cold winter.

I plant mine out in rows twelve inches apart in the traditional style on good ground manured or composted in winter. Take out a shallow furrow and dibble in holes about four to six inches apart. Lift the young seedlings when about eight inches tall and top and tail them before dropping them in the dibber holes. Water them in and leave them alone.

Fresh vegetables are now being harvested for the table regularly. Lettuce. radish, spring onions and now the first courgettes and Swiss chard leaves. The former makes fantastic soup and the latter brilliant as a stir fry ingredient but dont use much oil.

The social side of allotment gardening brings people together at this time of year to swap spare vegetable plants, tomato plants, courgettes, pumpkins, leeks and other new types worthy of a trial, and when its too hot to garden there are always plenty of sunny patios to sit down and relax on.

The Cold Greenhouse

As the heatwave continues most plants that had greenhouse protection have been moved outside leaving the grapes and tomatoes and four pots of Cape gooseberries which continue to grow very strongly. At this moment I still have space for them, but if they get much bigger they will need to go out somewhere.

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