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.


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.


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.

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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 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


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.


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.


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.


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.  


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.


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.


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.


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No plants will survive very long without good watering, and it’s even more crucial for potted plants. They may not have the same access to rainwater, drainage or natural water reserves depending on where they are placed. So here is our handy infographic to remind you how to water pot plants for great growing!

If you’re looking to give your potted plants a fabulous new home, then you’re in luck. At Primrose we have an incredible selection of all kinds of planters available.

How to water pot plants

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Catch up on the previous post in the series: How to Repot a Plant.

Next up is Part 4: How to Choose the Right Planter for Your Garden.

George at PrimroseGeorge works in the Primrose marketing team. As a lover of all things filmic, he also gets involved with our TV ads and web videos.

George’s idea of the perfect time in the garden is a long afternoon sitting in the shade with a good book. A cool breeze, peace and quiet… But of course, he’s usually disturbed by his energetic wire fox terrier, Poppy!

He writes about his misadventures in repotting plants and new discoveries about cat repellers.

See all of George’s posts.

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Gardening in the Rain

Why on earth would you want to try gardening in the rain? It’s a perfectly reasonable question. But, daft as it may seem, there are a surprising number of benefits if you’re prepared to brave the elements. And as our wet summer becomes an even wetter autumn, getting outside on drizzly days will enable you to get a huge amount more done in the garden. Plus, cloudy weather makes for cooler air, which is always a relief for hardworking gardeners. The damp keeps away most insects and, of course, the rain waters your plants for you. So grab your coat, and get outside!

What Can You Do in the Rain?

  • Planting. One common concern that puts people off gardening when it’s wet is whether you can really plant in the rain. In actual fact, it’s fine – as long as there’s no standing water. Just use a pot, or place in the garden, that has good drainage. For new seedlings, planting in the rain can be of great benefit since you don’t have to worry about watering them.
  • Feeding. As well as sitting back and making the most of the rain watering your plants for you, you can take the opportunity to feed them too. Get out there with your fertiliser and sprinkle around the base of each plant. The rain will then help it to run straight into the roots for maximum uptake.
  • Harvesting. Some fruiting plants and vegetables love wet weather, and will produce lots of great crops for you to harvest. So while the season is rainy, it’s the perfect time for picking salad plants like lettuce and watercress, or herbs like mint.

What Can You Do After the Rain?

  • Weeding. Just after a good downpour is the perfect time to get your weeding done. Heavy rainfall means damp soil, which loosens up the weeds’ roots, making them much easier to extract. This is particularly useful for weeds which are notoriously difficult to remove, such as dandelions and those with taproots. Taproots are the thick, original root stems of weeds like creeping buttercup and wood sorrel. It’s much better to get taproots out while the soil is wet so that all the offshoot roots also slide from the earth, since if they break off they can regrow into new plants.
  • Edging. If you’ve ever tried to neaten up the borders of your lawn, you’ll know it can be a challenge to dig a crisp edge in the turf. Garden edging – usually plastic or metal strips – are the best solution for maintaining a trim border, and just after a rainy day is the best time to install it. Just like with weeding, the damp soil is your friend here. It’s much easier to shape with a spade or trowel, and the edging pins will sink into the ground much more freely.
  • Tidying. Though rain is of course essential to a healthy garden, it can also leave a few problems in its wake. When you go outside after a downpour, look for anything that’s been washed out of place, particularly soil or fertiliser. Make sure you turn the compost heap too, if it’s an open one, to help with the air circulation and prevent it getting waterlogged.

Snail in Rain

How Can You Prepare Your Garden for the Rain?

Not all parts of your garden are going to appreciate a real British deluge, so it’s best to be prepared. If you’ve just planted seeds they may be vulnerable, but simply covering them with a plastic cloche or sheeting should shelter them from the worst of the weather. If you have fragile plants in pots, an easy alternative is just to bring them inside while the weather is bad.

What to Wear for Gardening When It Rains

Gardening can be mucky, and never more so than when it’s pouring outside. But don’t let that put you off – with the right clothing you can easily stay warm and dry. Obviously a raincoat is a must. But it’s also worth investing in a pair of waterproof trousers if you’re going to be outdoors for a while, as normal materials will quickly become soaked through and weigh you down. You’ll want something to cover your head, but a waterproof hat is actually better than a hood for gardening since it allows for more flexible neck movement as you’re working outside. For your feet, walking boots are generally more practical than wellies. They’re lighter and don’t restrict your ankles, which makes it much easier for trampling through undergrowth and flowerbeds. Just make sure to check if your boots need spraying with a waterproofing agent first.

Useful Kit to Cope with the Showers

  • Greenhouse. Although more of an investment, a greenhouse will offer a permanent sheltered spot for gardening in a downpour. You’ll be able to get on with repotting and planting seeds whenever the weather decides to turn. It can also be a useful area to have for unexpected rainfall, as you can shift delicate plants undercover in an instant without having to worry about causing a mess indoors.
  • Garden track. One of the best ways to deal with the muddy ground rainfall causes is some garden track. This is a plastic roll out path that provides a solid surface to ensure you don’t slip over on the wet lawn, and is especially useful for stopping wheelbarrows sinking into sodden earth.
  • Garden shade. Sometimes you may just want to relax in your garden without the risk of sudden rain spoiling your day. Having an awning or shade sail installed is a great way to cover your furniture or guests when you’re entertaining outside. No more events ruined by bad weather!

So I hope some of these ideas have inspired you to not be downcast the next time the clouds appear on your gardening day. As we’ve seen, there are always a few bits and pieces you can crack on with in the wet weather, and even some benefits that the rain brings. It’s a garden essential. And if all else fails, stay inside, put your feet up and enjoy a nice cup of tea. After all, you were out working hard in the garden all summer…

George at PrimroseGeorge works in the Primrose marketing team. As a lover of all things filmic, he also gets involved with our TV ads and web videos.

George’s idea of the perfect time in the garden is a long afternoon sitting in the shade with a good book. A cool breeze, peace and quiet… But of course, he’s usually disturbed by his energetic wire fox terrier, Poppy!

He writes about his misadventures in repotting plants and new discoveries about cat repellers.

See all of George’s posts.