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Primrose Germination Primrose need careful treatment in order to germinate, especially with regard to light and temperature. We give some advice here to help you get the best results out of the seed. Germination environment: environmental factors that can influence primula germination include soluble salts, pH, moisture, light and temperature. ~ Light. Light is important for primula germination. Without light, germination percentages drop by 10% to 15%, regardless of temperature. ~ Temperature. High temperatures of 25°C (77°F) reduce germination rate and percentage by as much as 50%; at low temperatures 10°C (50°F) primula seed doesn't germinate until after 21 days and yields a final germination percentage less than 25%. The ideal germination regime is to keep soil temperatures between 18°C – 20°C (64°F and 68°F) with seed on the compost surface and high humidity. Germination will start after 10 – 14 days. Seed can be covered with a light sprinkling of vermiculite at this stage to help maintain moisture levels. ~ Moisture. To control pathogens and provide adequate oxygen, keep media moderately moist but avoid prolonged saturation. If moisture control is difficult, cover seed with a light layer of coarse vermiculite. ~ pH and salts. Primrose are sensitive to pH and soluble salts. The germination media pH should be between 5.5 and 5.8, and soluble salts low. Primrose is not an easy crop to germinate, but proper seed treatment and environmental conditions can make your germination efforts fruitful. Pricking off. Prick off seedlings once they are big enough to handle without damaging the root system. Grow on in a cold shaded area until plants have established when they should be moved to a cold area (with frost protection) to grow on. Outdoor shaded cold frames are ideal if available. Growing on The young plants will be ready for transplanting between six and eight weeks from sowing. Transplant directly into the final unit, which will be a 9 or 10 cm (4in) pot or a large cell pack, using compost with a pH of 5.8 - 6.0. The plants will benefit from the addition to the media of a proportion of clay/loam/bark, which not only improves and maintains the structure of the compost, but also acts as a buffer which helps to prevent swings in moisture and feed levels. Place the plants in a cool, airy environment, and once the plants are established remove any shading, as the better light will help ensure strong growing, compact plants, and help to prevent fungal disease. Keep the plants moist at all times. However, avoid over-watering and if possible water early in the day to allow the foliage to dry out before nightfall. Keep summertime temperatures as low as possible, and during the winter maintain temperatures of between 0° and 5°C (32° – 40°F) for best quality plants. Primroses are hungry feeders, and a feed programme is essential for best quality plants. Start feeding about four weeks after potting, using a well balanced 1.1.1 liquid feed about once a week while the plants are growing actively. Reduce the feeds if the plants are being grown cold (frost protection or below). Whitefly is the major pest of primrose, plants should be sprayed as necessary. Leaf spot occurs when temperatures are low and humidity is high. Prevention is much better than any cure and the disease can usually be avoided by keeping the foliage dry. Botrytis can be troublesome when old leaves have died on the plant, or been damaged by drying out or frost. In the worst cases it spreads into the crown, killing the plant altogether. Always keep the pots uniformly moist, and apply fungicide spray as necessary. |
