How to grow auriculas

The perfect petals of auricula flowers
Image: shutterstock

Auriculas are beautiful perennials that produce such perfect flowers that people often feel the need to touch them to check that they're real! They've come a long way from the simple Primula auricula from which they take their name. Whether you prefer border auriculas, alpines or show types, over four centuries of breeding have brought them to a state of perfection in form and colour. Here, auricula specialists Pamela and Derek Salt share their tips for growing this enchanting group of plants.

Browse our full range of alpine plants for more inspiration.

What is an auricula?

Primula auricula is a yellow-flowered plant of the high alps. Its leaves are comparatively thick and roundish in outline, hence the common name 'bear's ears' and botanical name auricula. The leaves are often covered with a whitish meal which gives them the better known, common name 'dusty millers'. The flowers have five yellow petals and a central white area, sometimes covered with meal (called 'paste' by auricula growers).

In the wild, Primula auricula grows with Primula rubra which is a non-mealy plant with rosy pink flowers and a white eye. A hybrid between these two species occurs naturally and has been developed into an attractive range of plants known as Primula x pubescens. This hybrid is also thought to have given rise to auriculas. Other species have possibly been introduced during their development.

The four main types of auricula

Primula Auricula flowers floating in a bowl of water
Image: shutterstock

1. Border auriculas

Border auriculas are the types grown mainly in the garden. They often have mealy leaves, and flowers in a wide range of colours. They make a good splash of spring colour but are not so finely developed as the other types.

2. Alpine auriculas

Alpine auriculas can also be grown out of doors but the perfection of their blooms is best produced in a cold frame or well-ventilated greenhouse. They do not have any meal on their leaves or flowers. The flowers are always thrum-eyed, open flat, and are circular in outline. This also applies to the show varieties. The centre of the flower is either gold or light (almost white) in colour. The petals are bright jewel colours which shade lighter towards the outer edge.

3. Show varieties

Show varieties are generally regarded as the aristocrats of auriculas and are virtually always grown under protection. Some varieties (but not all) have meal on the leaves. They all have a ring of white paste around the tube. There are two main types - the selfs and the edged.

The selfs have petals of clear bright colours without any shading. The edged types, regarded by auricula fanciers as the peak of perfection are botanical oddities. The tissue of the petals is structurally identical to that of a leaf. They are green and, instead of wilting and dropping like a petal, when they 'go over' they turn yellow like an autumn leaf.

There is an irregular 'black' area between the paste and the green petal edge which is called the body colour. The edge may be plain green (a green edged variety) or covered with meal. Depending on the amount of meal, it's then either a grey or white edged variety.

Fancies are basically edged types in which the body colour is not black. Thus a grey or green-edged flower which has a dark red or purple body colour is classified as a fancy and not an edged variety. (This used not to be the case and in some flowers the distinction between dark red and 'black' could be argued about). The more obvious fancies are those which, whilst still retaining the central white paste, have two distinct colours, usually yellow and green or red and green.

Striped varieties are usually lumped in with the fancies. This type was almost lost and new varieties are, slowly, now being produced. In some auricula show schedules they are separately classified. There appears to be a genetic link between striping and a rather ragged petal. The striped varieties do not, as yet, have the perfect circular outline.

4. Double auriculas

Double auriculas have more than one row of petals. They can be double forms of alpine or show self types, and striped doubles that were popular in the sixteenth century are now beginning to reappear. The 'classical' form has smooth edged petals arranged like a double camellia. Other forms are usually more double and may resemble anything from a French marigold to a shrub rose flower in form.

How to propagate auriculas

Named varieties of auricula do not come true from seed, they are reproduced by offsets. Plants are divided when they are repotted after flowering. Shoots can also be rooted as stem cuttings. Seed is a suitable method of producing a good number of plants for garden use and is the way of producing new varieties.

Sowing seed straight from the pod will produce the fastest germination and the most vigorous seedlings. It has the slight disadvantage of entailing the overwintering of young plants and it is of course only available to those who produce their own seed.

Winter and spring sowing are more common. If seed has to be stored it must be kept cool. A screw-topped jar in the bottom of the fridge is the best place for it.

Many growers treat the seed like other alpines. It is sown early in the new year and placed in a cold frame where the seedlings will start to appear in March or April. Auriculas can also be spring sown and either placed in a cold frame or under the greenhouse bench. Whatever the time of sowing they must be kept cool.

A soil-less seed sowing compost can be used but a loam-based John Innes type seed compost is more common, and essential for the winter sowing. In both cases coarse sand or grit can be added to improve drainage.

The compost should be levelled and moistened before the seed is scattered, very thinly, on the surface. It can then be just covered with glass or plastic and, when the seedlings emerge, their roots can be lightly covered with sand, compost or vermiculite. The alternative is to cover the seed with grit or coarse sharp sand after sowing. The seedlings are quite capable of pushing through this covering which prevents the growth of algae and moss on the compost surface and also permits watering with a fine rose. This covering is essential for winter-sown seed.

The young seedlings must be kept cool. Provided that they have been sown thinly they can be allowed to grow to a reasonable size before they are pricked out into seed trays. There is no point in battling with tiny seedlings which, as they-have no stem, are difficult to handle. A multipurpose compost or an auricula compost with extra sand can be used at this stage. Late summer/autumn sown seedlings are generally not potted until the spring. Winter and spring sown plants can be established in their pots by autumn. A 7cm pot is quite large enough for a young plant beware of over potting.

Growing on auriculas

A variety of composts are used for growing auriculas. They need good drainage but also the ability to hold water and plant food. At the extremes, we know two successful growers one of whom uses a straight multipurpose compost and the other uses a mixture of mole-hill soil and well rotted cow muck with the bottom third of his pots filled with drainage material!

Someone growing for the first time might like to try our mixture, which is two parts John Innes Potting Compost No.1, two parts soil-less Potting Compost and one part grit. We use this in plastic pots. For clay pots the amount of grit could be halved.

It's wise to re-pot annually. Some growers merely shake off some of the loose compost, remove offsets and repot. Others shake off all the compost then split the plants before potting. Whichever approach you take, any dead and rotting roots should be removed and pests like vine weevil removed. Never re-pot in hot weather.

Caring for auriculas

The best auriculas are still grown in clay pots. Their ability to dry out faster than plastic makes it easier to avoid over watering, particularly in the winter, but they do need more frequent watering in warm weather.

Auriculas of all types are perfectly hardy. They're only grown under glass to prevent the rain washing the meal off the leaves or spoiling the appearance of the flowers. The border types grow very well in the same conditions as polyanthus. A well-drained, but not dry soil suits them. Ideally they should have some shade from direct midday sunshine particularly during the summer.

The rest are happiest in a shady, or north-facing cold frame for most of the year, simply being brought into a well-ventilated, cold and shaded greenhouse to flower. An alpine house suits them well. It's not necessary to have expensive structures. Very good plants can be produced in a shady spot with a glass or plastic frame suspended overhead.

They make no fresh growth in winter so require very little water. If the pots are sunk up to their rims in sand they don't generally require watering between November and February. In these conditions, a frameful of our plants survived -18C without any losses. If your plants look quite appalling in February with masses of dead leaves and a small green centre you've probably got their winter conditions right! Removing the old leaves and watering will rapidly get them growing again and the flowers will soon follow.

It's tremendously exciting when seedlings start to flower. Don't expect them all to be new varieties! Most will be less than perfect, but you normally get a few good ones. Double flowered seedlings may only produce single flowers in their first season so, if the colour and form look reasonable, grow them on for another season. On the other hand, some vigorous young seedlings produce most exciting double flowers but fail to repeat the performance however many years you grow them on.

One final thought: the flowers are beautifully scented, a fact often overlooked by those who write about them. Check out our round-up of RHS members' favourite scented plants for more ideas.

About the authors:

Auricula specialists Pamela and Derek Salt.

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