It loves cool temperatures but no frost, bright light conditions without blazing sun and fresh, moist soil. The cup primula knows exactly what it wants. Those who take their requirements into account will be rewarded with a long flowering period on the windowsill and on the summer balcony. Planted out in the flower bed, the Asian plant beauty steals the show from other summer perennials with its decorative leaf rosettes and colorful flowers. So much floral splendor is far too good for a one-year cultivation. The following care instructions explain in detail how to cultivate the Primula obconica as a pot flower professionally and perennial.


  • Genus: Primroses (Primula)
  • Name of the species: cup primrose (Primula obconica)
  • Trivial names: poison primrose, cowslip
  • herbaceous flowering plant
  • Native to the montane forests of central and southern China, Tibet and Thailand
  • Minimum temperature: 5 degrees Celsius
  • Flowering time possible all year round, depending on the variety
  • Basal leaf rosettes with stalked, finely hairy leaves
  • Leaf blade ovate to elliptic, 2-11 cm wide and 3-14 cm long

Care Instructions

The cup primrose not only produces the most beautiful flowers and the most lush foliage, but also contains the highest proportion of poisonous primine. The toxin is mainly found in the fine glandular hairs and triggers allergic reactions when it comes into contact with the skin. Therefore, it rightly bears the nickname Poison Primrose.


In order for the cup primrose to live up to its reputation as the flower primus among the primrose plants, bright lighting conditions and cool temperatures are important. Therefore, assign the potted flower in living rooms and on the summer balcony a place with these general conditions:

  • Bright location, without direct sunlight at midday
  • Mild sunshine in the morning or evening is beneficial
  • Temperatures between 10 and 15 degrees Celsius

From the end of April/beginning of May, the window for planting primroses outdoors opens. Choose a semi-shady location here . A Primula obconica feels at home where the canopy of trees and shrubs filters the sunlight. Only in full shade will you wait in vain for the pretty cowslips.

Tip : In order for a cup primrose to bloom in a warm living room at temperatures above 15 degrees Celsius, higher humidity is required. To do this, spray the plant daily with a gentle mist of lukewarm, lime-free water.

substrate and soil

The ideal pot substrate should be equal to a loose, humus-rich forest soil. A mix of potting soil , leaf compost and fine-grained pine bark or crushed bark mulch is well suited for this purpose . Please make sure that the peat content is as low as possible and instead use adequate substrate mixtures with peat substitutes, such as coconut or wood fibers.

If you have planned a place in the bed for your cup primrose, the soil should be nutrient-rich and fresh and moist. Although the flower wants a moist soil, the location must not become waterlogged. Furthermore, a slightly acidic to neutral pH is desirable.


Water a cup primrose regularly so that the soil is constantly slightly moist . If the surface dries, please pour lime-free, room-warm water on the substrate until the saucer fills up. If this is not filled with pebbles, pour out the excess irrigation water after a few minutes so that no waterlogging develops.

The cooler and darker the location, the less often there is a need for watering. This is especially true during the winter when the plant almost completely stops growing.

A short finger test in the bed gives more detailed information about the moisture content of the soil. Press your thumb into the ground a little. If the upper 2-3 cm feel dry, it is watered.


If the first leaves and flower stalks sprout, please start with the nutrient supply. During the growth and flowering period, apply a phosphorus-rich liquid fertilizer . Add this to the irrigation water every 2 weeks. The dosage specified by the manufacturer should be reduced by half to avoid the risk of over-fertilization. At the end of the flowering period, please stop adding fertilizer until the next fresh shoot appears.

In the bed, the cup primrose gratefully accepts an organic fertilizer every 3 to 4 weeks from April to September . Sieved leaf compost , horn shavings or guano granules work very lightly into the soil with a rake and pour in rainwater. Alternatively, to protect the sensitive roots, you can spray the soil every 2 to 3 weeks with nettle manure.

To cut

The cowslip does not receive a pruning in the sense of a shape and maintenance cut. Withered flowers are regularly trimmed to make room for more flowers. Furthermore, the well-groomed appearance in the pot and bed is maintained throughout the flowering period. Ideally, pluck out dead leaves. If this doesn’t work, cut off dead leaves with a sharp, sanitized knife or scissors and the petiole.


Since the cup primrose is not hardy , you will part with plants in the bed after one season. The benefit of hibernation is out of proportion to the effort involved, especially since the plant will not survive the stress caused by moving to the winter quarters.

In pot culture, on the other hand, there are good prospects of caring for the pretty flowering plant for several years. How to hibernate:

  • Put cup primroses from the balcony as soon as the temperature falls below 5 degrees Celsius
  • Place in a bright window seat at a cool 10 to 15 degrees Celsius
  • Water sparingly and do not fertilize
  • Air the room daily

If the cowslip proved to be quite thirsty in the middle of the flowering period, the water requirement drops significantly in winter. Although the substrate must not dry out, penetrating moisture should be avoided at all costs.


After the plant has been able to gather fresh strength throughout the winter, signal your cup primula the start of the new season by repotting it in fresh soil. In March, you can wake up the cowslip from hibernation with this care measure by proceeding as follows:

  • The new flower pot is only 2-3 cm larger in diameter and has a water drain
  • Lay expanded clay balls or potsherds on the floor as a water-bearing layer
  • Cover the drainage with a piece of fabric or fleece that is permeable to air and water
  • Pour in a first layer of the recommended substrate and make a well in it with your fist
  • Plant the potted cup primrose in the hollow so that the previous planting depth is maintained

Water the repotted plant and place it in a light to partially shaded window seat with temperatures around 15 degrees Celsius. The supply of nutrients in the potting soil covers the needs in the following 6 to 8 weeks. Only then does the application of fertilizer begin again.


Once the flowering cup primrose has found a permanent place in gardeners’ hearts, the desire for more specimens is obvious. The following two propagation methods have proven themselves in the hobby garden:

Since the seeds of a cup primrose – in contrast to their winter-hardy counterparts – germinate without stratification, sowing is uncomplicated. You can either harvest the seeds at the end of the flowering period or purchase certified seeds from specialist retailers. The advantage of buying is that you know in advance exactly what color the primula will be. With seeds from your own harvest, you will have to be surprised by the floral result. Please use fresh seed if possible, because after 8 months of storage the germination rate decreases dramatically. How to sow:

  • Fill a seed box with peat sand or lean potting soil
  • Scatter the seeds on top and sieve sand over it as thick as a seed
  • Moisten lightly with a fine spray of filtered rainwater and place a pane of glass on top

In a partially shaded location at temperatures around 15 degrees Celsius, germination takes 2 to 4 weeks. As soon as the cotyledons sprout, the glass pane can be removed. Please keep the substrate slightly moist throughout the entire period and ensure good air circulation to prevent mold from forming. The strongest seedlings are pricked out in individual pots if they have at least 2 true pairs of leaves above the cotyledons.

If a cup primrose survived the winter unscathed, it can be divided in spring in connection with the change to fresh substrate. This care measure also contributes to the rejuvenation of the plant. To do this, place the potted root ball on a stable surface. With a freshly sharpened and clean knife, cut the plant in half. Please powder the cuts with rock dust or charcoal ash. Each section is then planted in its own flower pot and immediately cared for like an adult primula.


Yellow leaves are one of the most common problems in caring for cup primroses. The damage is not caused by disease, but by using hard water for watering and spraying. In the long run, the lime content accumulates in the substrate. The roots can no longer absorb important nutrients such as iron and magnesium. As a result, leaf chlorosis develops. As a visible symptom, the leaves take on a yellowish color with the green leaf veins prominent. From now on, please only water with lime-free water. In the short term, you can compensate for the deficiency by fertilizing with Epsom salt (magnesium sulfate). Add 7-8 grams of magnesium sulphate to 1 liter of decalcified water and water the cup primrose with it until the foliage has turned its rich green color again.

The cup primrose is one of the most flowering primrose plants and convinces with its uncomplicated care. In a bright location with 10 to 15 degrees Celsius, the hoped-for blooming splendor will not be long in coming. Depending on the variety, the plant inspires in spring or summer with its colorful flowers, accompanied by a dense rosette of leaves. Regular watering with soft water and fertilizing every 2 weeks complete the care. Withered and faded areas should be cleaned consistently for a neat look. The Primula obconica prefers to spend its winter break in a bright place at 10-15 degrees Celsius.

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