Primroses: sowing, flowering time & plant care

Primroses are the quintessential harbingers of spring. But what should be considered when planting and caring for the early and colourful spring-flowering primrose?

Colourful primroses (Primula) in small pots are a permanent fixture in supermarkets and hardware stores in late winter. With low prices and a huge selection, it is tempting to stock up every year for the new gardening season. However, the little plants are very rarely annuals and only really feel at home when planted out in the garden. If you take care of a few things, primrose (Primulaceae) are also very resistant to diseases and pests. So you can enjoy the colourful flowers for years.

Planting primroses: Flowering time, planting time and location

The botanical name Primula means “the first” – very appropriate for an early bloomer, with some species beginning to bloom as early as January. There are a total of 500 primrose species, which are in flower from February to May. Candelabra primroses (Primula bulleyana and Primula bullesiana-hybrids) even bloom from June to July. The single, double or frilled flowers are rarely solitary. Usually 2 to 25 flowerheads stand together as umbels or whorls and shine in lavender, magenta, pink to purple, depending on the species. More rarely you can find red and from white to yellow flowers. However, in order to enjoy your primroses for years to come, you should take a few things into consideration when planting them.

• Planting time: spring or autumn
• Habitat: Sun or partial shade; no direct sun
• Soil: loose, nutrient-rich (admixture compost) garden soil, good water retention
• Soil pH: slightly acidic

What to consider when planting primroses

Originally, the primrose is native to the entire Northern Hemisphere. This very persistent wild and garden perennial, once planted out in the garden, blooms again the following year. With this step-by-step guide, planting will definitely succeed.

• The ground must not be frozen
• Planting hole: 20cm depth; 20cm diameter
• Loosen soil and add compost
• Remove the primrose from the pot and open the root crown at the root ball.
• Primrose is placed in the planting hole and the root ball is covered with soil

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If you observe these conditions, you can plant primroses at your convenience outside in the garden or on the balcony. Primroses do well in pots, beds, rock gardens or window boxes. As early bloomers, they provide the first accents of colour as underplanting for hedges, shrubs and trees. Julia’s primrose (Primula juliae) provides beautiful ground cover. Rosy primroses (Primula rosea) are suitable for somewhat wetter sites, because of their high tolerance to wetness.

Note: most commercially available primroses were grown in the greenhouse. They are not accustomed to cold temperatures. Therefore, it is best to acclimatise the plants for a few days in a cool but protected place before planting.

Combination with other plants

Since primroses are in bloom from February to May, it is worth combining them with other early bloomers, such as daffodils (Narcissus), snowdrops (Galanthus) or tulips (Tulipa). But they can also be combined with horned pansy (Viola cornuta), common daisy (Bellis perennis) and oxeye daisies (Leucanthemum vulgare). These have a slightly later blooming period that overlaps with that of the primrose and will keep your garden in full bloom well into the summer. In the bed, ferns, grasses or late-blooming perennials fill the gaps left after the primroses have bloomed.

Primrose as a houseplant

As a houseplant, for example, German primroses (Primula obconica) bring colour to the dreariness of winter and bring spring feelings into the home. You can even get a little of these spring feelings right away with a primrose. Because to give someone a primrose means: “Give me the key to your heart”. But, if you want the primrose to feel comfortable in the room, there are a few things to consider.

• Location: bright and cool room (for example, north window place).
• The cooler it is, the longer the flowering phase (around 15°C).
• Watering: lukewarm, low-calcium water so that root ball does not dry out; no waterlogging
• Fertilisation: during flowering every 2 weeks
• Put outside in summer
• Bring indoors before the first frost to overwinter
• Repot in spring if necessary

Note: after flowering, primroses can also be easily planted out in the garden. Many species bloom a second time during the summer.

Buy primroses or propagate them yourself

Every spring, the shops attract new customers with colourful little pots of primroses. But the these cheerful little plants do not necessarily have to be bought. If you already have older primroses at home or have harvested seeds in the previous year, you can grow new primroses yourself with a little effort.

Buying primroses

From January, primroses are offered as small potted plants in supermarkets and hardware stores. After purchase, the primroses can first be well acclimatised indoors for four to five days before planting out. In perennial nurseries you can also find much more robust, small-flowered garden forms.

Primroses: harvesting and sowing seeds

Primroses are easily propagated by sowing. This results in the recombination of the parents. Therefore, when combining different varieties, each seed is like a colourful surprise egg. If you want to be surprised, simply stop at the end of the season to clean out the withered flowerheads. The formation of the seed set starts all by itself after fertilisation. After that, proceed as follows to harvest seeds:

• Cut off capsule fruits before they have become really brown and scrawny
• Allow to ripen on cloth and wipe off when pods are dry, dark coloured but still closed
• Seeds are ripe when they rattle in the capsule
• Shake out the 10 to 100 brown seeds
• Store seeds in screw-top jar in refrigerator until sowing time

Some species such as English primroses (Primula acaulis) also self-seed. Here, the capsule fruits simply remain on the plant. However, for independent propagation to really work, the soil should be as loamy as possible. For all others, the harvested or purchased seeds are sown in the spring between February and April, so that the primroses bloom the following year. The seeds used should not be older than 10 months. Germination capacity is at its highest at that point. Germination will certainly work out if you follow a few pointers when sowing.

• February to April: Scatter seeds on sowing soil
• Sprinkle seeds very thinly with sand (light germination!)
• Moisten soil with hand sprayer
• Ideal germination temperature: 10 to 15 °C (e.g. balcony)
• Transparent cover for humidity (ventilate daily from germination onwards).
• Germination time: 2 to 3 weeks
• Pricking out into individual pots: 4 – 7 weeks after sowing.

Note: primroses are cold germinators. The seeds need a cold period to germinate better and more uniformly. Therefore, a short frost during the germination period can even be beneficial.

Propagating primroses by division

Primrose has rhizomes that grow underground. These thickened shoot axes serve to store nutrients and survive bad weather. However, they can also be used for propagation by division. Division is suitable only with older plants with a diameter of 15cm or more.

• Dig up rootstock after flowering
• Remove soil from the rootstock and divide with a spade.
• Replant at a distance of min. 20cm

Note: dividing the plants every 3 to 5 years will promote their longevity.

Caring for and watering primroses

Primroses are very undemanding fellows. They do not even need to be cut back. Still, there are a few little things to keep in mind to make your flowers feel completely at home.

• Fertilisation: Spring, when leaves sprout (organic fertiliser or compost).
• Watering: plenty of water during flowering; soil moist, but not wet; no waterlogging!
• Deadhead faded flowerheads and dead plant parts

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Primroses are sensitive to drought, but too much wetness increases the risk of gray mould (Botrytis) or root and stem rot.

Note: in young primroses magnesium deficiency leads to yellowing of the leaves. Here, the solution is 8 grams of magnesium sulfate (Epsom salt) dissolved in a litre of irrigation water.

Overwintering perennial primroses

Primroses are rarely annuals. Most species among them are perennials to semi-shrubs. They partially retreat into the ground in the autumn, and only some more sensitive varieties need light winter protection. So once planted out, you do not have to do much to protect your plants. However, if the temperatures stay below – 5°C for a longer period of time, it will be too cold for the primroses. In the bed, simply cover your primroses with a nice layer of brushwood, leaves, moss, bark mulch or spruce branches. Potted primroses are best placed in a sheltered, cool spot at 3°C to 10°C – for example, in the stairwell or basement. Learn more about how to overwinter primroses in our dedicated article.