Flowers, Gardening, Gardens, Grow Your Own, How To, Planting, Plants, Watering

Rhododendrons and azaleas usually bear their spectacular, large, often scented flowers in spring – but do you know the difference between the two?

Well, both are in the genus Rhododendron –  but azaleas can be distinguished by having five stamens per flower (one per lobe), whereas rhododendrons have 10 or more (two per lobe). Azaleas can be deciduous or evergreen but rhododendrons are all evergreen. Finally there is a difference in size. Azaleas are small to medium shrubs – rhododendrons range from prostrate shrubs to huge trees.

Within this guide you will find information about some of the different varieties of rhododendron and azaleas, as well as information about how to successfully plant and maintain your own.

Main Species

There are more than 28,000 rhododendron or azalea hybrids, as the plants readily cross breed. However, here are the most popular varieties for gardeners:

  • Hybrids or hardy hybrids: What gardeners would consider a ‘traditional’ rhododendron with large flower trusses, some scented, blooming anywhere between January until July – often growing very large.
  • Dwarf rhododendrons: Mainly alpine varieties, ranging from 20cm-80cm, flowering in April.
  • Yakushimanum: Mound-shaped plants reaching 80-100cm, often with unusual leaves. Many brilliant flower colours available.
  • Williamsianum: Unusual rounded leaves, 80-100cm.
  • Deciduous azaleas: Sun lovers, growing up to 150cm, often scented, (especially R. luteum) with rich autumn foliage. They can be divided into Species (Sciadorhodion, Pentanthera, Rhodora, Sinensi or Brachycalyx); Ghent (the oldest hybrid group with multiple small flowers); Knaphill (large flowered hybrids, some of which are scented); Mollis (earlier flowering, more compact and spreading); Rustica (small double flowers, some scented). Other deciduous azaleas include Pratt hybrids, viscosum, occidentale and the Northern Lights series.
  • Evergreen azaleas: Small, slow-growers, suitable for pots, up to 75cm, some are prostrate in habit, with autumn colour. Flowering season is usually May.

Planting

Choose a sheltered site with dappled shade, however, dwarf alpine species will tolerate full sun. Avoid sites exposed to early morning sun in spring, as this may damage frosted flowers.

The most important factor deciding whether rhododendrons or azaleas will grow well in your garden is the pH of your soil. They must have moist but well-drained, acid soil between pH 5.0 and 6.0 that is rich in organic matter. Reducing soil pH is not easy.

October or March/April are the best times for planting – dig in acidic organic matter before you begin (leafmould, rotting pine needles or composted bracken will work well). Don’t just concentrate on the planting hole – mix well around the surrounding soil. Don’t plant deeply, as rhododendrons are surface rooters. Apply a loose 8cm mulch of acidic organic material and water well to finish.

Care

To keep your plants performing at their best, in spring, apply slow-release ericaceous fertiliser and renew the acidic mulch and keep well watered.

Rhododendrons grow best in areas of high rainfall, which is naturally slightly acidic. Using tap water, especially in hard water districts, is not good for the plant as it contains too much calcium which reduces the acidity around the plant’s roots. However, if rain water runs out, tap water is OK to use for a month or so in summer.

Rhododendrons don’t require pruning apart from removing dead wood and deadheading if practical. If the plant outgrows its space, cutting back is tolerated best from deciduous azaleas and rough-barked rhododendrons. After cutting back, mulch, feed and keep well watered.

Growing in Containers

If you have alkaline soil, grow rhododendrons and azaleas as container plants. Use ericaceous loam-based compost and repot every other year into fresh compost in spring. When not fully repotting, top dress the top 5cm of growing medium with fresh compost.

Common Problems

Most problems with rhododendrons and azaleas stem from the soil being too alkaline, drought or other extreme weather conditions. Here are signs to look out for:

  • Non-flowering and bud drop: Flower buds actually start forming in late summer – dry conditions at this time can lead to a total bud formation failure or a partial formation, causing buds to dry up and dropping unopened in spring. Mulch and water thoroughly and regularly during dry periods in summer.
  • Leaf drop: Older leaves droop and roll, then drop off, following extreme moisture conditions – drought or waterlogging. Newer leaves show browning at the leaf tip or edge. However, it is normal for the shrub to shed some older leaves in spring and summer.
  • Leaf droop: Usually a response to severe cold, but they usually recover.
  • Leaf scorch/flower damage: Often caused by windy, cold or wet weather.
  • Yellowing foliage: Caused by nutrient deficiency known as chlorosis, an iron deficiency caused by high alkalinity in the soil.
  • Pests: Vine weevil can be a nuisance for container-grown plants, as can rhododendron leafhopper and scale insects.
  • Diseases: Relatively uncommon are bud blast, azalea gall and honey fungus.

Composting, Flowers, Gardening, Grow Your Own, How To, Planting, Plants, Watering, Wildlife

Rose

There is no doubt that roses are one of the most popular flowers to grow in Britain. In fact, so many are planted each year that if you set them out as a single row these plants would circle the equator! With the proper care and maintenance you can expect your rose to last for at least 20 years. However, many roses fail to thrive and a lot of that is due to improper planting and care. There are several elements to consider before attempting to plant a rose in your garden and this step-by-step guide should help you to navigate the pitfalls ensuring your rose is a success!

Planting

Planting Position

Choosing the correct position for planting your rose is crucial. If it is not in a suitable spot it will not thrive. Plenty of sun is needed for your rose to grow, slight shade in the afternoon is good but not continuous shade. Your rose needs shelter from the cold winds. A nearby hedge or fence is good but should not be too close that it shades the bush. Your rose will need good drainage as it will not grow in waterlogged soil.

Soil Conditions 

When planting your rose it is important that the soil is suitable. Ideally the soil should be medium loam, slightly acid with a PH of 6.0-6.5 and reasonably rich in plant foods and humus. Roses cannot thrive if the soil conditions are poor. Roses should be planted from Late October to March and the ground should not be waterlogged or frozen.

Preparing the Rose

Cut off any leaves, hips or buds that may still be present. If the stems are shrivelled place all of the bush in water for several hours. Cut off any decayed or thin shoots before planting. Plunge roots into a bucket of water if they seem dry. It is crucial that the roots do not dry out before planting and make sure they remain covered until you are ready to set the bush in the planting hole. Cut back any long or damaged roots to about 30cm.

Planting the Rose

Mark out planting stations to make sure your rose bush has enough space. There should be a distance of about a metre between each plant. When planting make sure that the bud union is about 2-3cm below the surface.

Caring and Maintenance

Mulching

Roses benefit from having a layer of mulch on the soil surface around the plants as it reduces weeds, keeps soil moist in summer, improves soil structure, reduces black spots and some mulching material provides plant foods. Some suitable materials used for mulching include moist peat, shredded bark, well rotted manure, good garden compost and leaf mould. Prepare the soil surface for mulching by clearing away debris, dead leaves and weeds. Water the soil surface if it is dry. Spread a 5-7cm layer around the rose. Mulching reduces the need for watering and hoeing but does not replace the need for good feeding.

Watering

Roses have a deep-rooting habit meaning that the watering of established plants is not crucial in some seasons. However, some roses need watering after a few days of dry weather. For example, newly planted roses, climbers growing against walls and roses planted in sandy soils. All roses will need plenty of water in a period of drought in spring and summer. When watering, use about 5 litres of water for each bush or standard rose and 15 litres for a climber.

Hoeing

The main purpose of hoeing is to keep down weeds that are not smothered by mulching. Hoeing needs to be done frequently to make sure that the underground parts of the weeds are starved. Do not hoe any deeper than 2-3cm below the surface or the roots could be damaged.

Cutting

Roses are perhaps the most popular flower for cutting and using as decoration. To make sure you don’t weaken the rose bush, do not take more than one third of the flowering stem with the flower. Cut just above an outward facing bud. Do not cut struggling or newly planted roses.  

Feeding

Roses make heavy demands on plant food reserves in soil. If one or more vital elements run short your rose will not thrive. Feed your rose every year using a proprietary compound fertiliser containing nitrogen, phosphates and potash. You can use powder or granular fertiliser, liquid fertilisers or foliar feeding.

Deadheading

It is important to regularly remove dead blooms. Remove the whole truss when the flowers have faded. Cut the stem just above the second or third leaf down. This will help the rose conserve energy.

Pruning

Roses do not produce shoots that increase in size steadily each year. Therefore, if they are not pruned the rose becomes a mass of live and dead wood. The purpose of pruning is to get rid of the dead wood each year and encourage the regular development of strong and healthy stems. For more details click here.