Growing Azaleas

• All Azalea are Rhododendron but not all Rhododendron are Azaleas so now we have that as clear as a muddy pond what is an Azalea?

• An Azalea is an evergreen or decidious flowering shrub.
• It is a tender house plant and a hardy garden plant often grown in Scotland.
• Azaleas are scented or without scent. Whatever you think ‘muddy’ they are not.
• ‘Azalea are some of the most gay and brilliant flowering shrubs yet grown.’
• For the technically minded Azaleas are in the genus Rhododendron, with evergreen azaleas in the subgenus Tsutsusi and deciduous azaleas in the subgenus Pentanthera.

In the rest of this article there are sections on:

1. Cultivation of Azaleas
2. Soil and Planting
3. Watering
4. General growing Tips
5. Selecting your Azaleas
   
6. Types of Azaleas

Cultivation of Azalea

• Soil and planting
o Azaleas need an acid soil (pH 4.5-6.0) is best. Prepare the soil over a good area say 4 feet by 4 feet or together with other Azaleas in a larger bed.
o Azaleas do not like “wet feet”. Good drainage can be provided by planting azaleas with the tops of their root balls a few inches above ground level and mounding the soil up to the plants. This is particularly important with heavy clay soil. Roots are fibrous and tend to be near the surface so don’t hoe too close
o Azaleas are relatively pest-free, forgiving and easy to grow plants. They like to be mutually supporting so closer planting (say 3 feet for stronger growers) is better for general health.
o Mulch with peat, pine bark or wood chips to keep moisture in the ground, even out changes in the soil temperature and keep weeds down. An inch or so around the roots is desirable.

• Watering
o Azaleas like moist soil at their roots. This may require supplemental watering at least until plants are established in the ground for a few years.
o Adequate water after flowering helps to produce more flower buds for next year.
o An infrequent deep soaking is more effective than superficial sprinkling. If the Autumn has been dry water well before winter.

• General Growing Tips
o Azaleas in the garden are frost hardy. Young plants may be less cold hardy than older plants of the same variety. A plant in poor health will be less cold hardy than a vigorous plant.
o High shade is preferable but deciduous varieties do well in full sun. Whilst more sun typically produces more compact plants with more blooms the blooms will not last as long.
o Established azaleas do not need fertilizer but a little sulphate of ammonia in spring gives a nitrogen boost and potash if flowering is poor.
o To avoid inducing new growth which may be killed in the winter, do any fertilizing in late winter or early spring.
o Shortening or removal of long slender stems with no side shoots and cutting out dead wood may be done at any time. To avoid cutting off next year’s flower buds, do major pruning of azaleas soon after they bloom.
o Azaleas can be transplanted in September – not too deep and firm treading.

• Selecting your Azaleas
o Mollis hybrids do not like shade or frost pockets for optimum flowering. They will grow well and spread to form an attractive colony.
o Knaphill hybrids may be grown anywhere
o Buy the largest Hardy Japanese evergreen hybrids you can afford. If it has been grown on for 3 or 4 years it is strong and hardy and should do very well in your garden.
o For ground cover or the front of a bed try the white flowered ‘Palestrina’
o For the back try taller plants with light colours R. luteum, vaseyii, viscosum or arborescence.
o For specimen plants Azalea Coccinea Speciosa or R obtusum are recommended
o There is a good table of colour, habit and size of different varieties on the Scottish supplier Braevallich Nursery . I think I will try some july flowering varieties http://www.brae.co.uk/species/Azalea/list.html