Agapanthus prefers a neutral, well-drained, moderately fertile soil1. Soil that is too rich promotes lush, soft growth that is prone to winter damage1. Keep in a warm position, sheltered from wind. This is a waterwise plant that tolerates a variety of sun conditions – from full sun, to shade, although some sun is needed for optimal blooming. If your climate is very hot, try growing under partial shade conditions1. Keep well watered during the growing season. Yellow leaf tips indicate overwatering1.
Follow a regular watering schedule during the first year’s growing season to establish a deep, extensive root system1. After that, it only needs water when the top 3 inches (~7 cm) of soil is dry1.
Divide the clumps every 3 years or so, in spring1.
For a neat appearance, remove old foliage1.
Keep in mind when planting that Blue Triumphator is thought of as half hardy, so it will need cloching or fleece protection when the temperature dips.Seed can be sown fresh, in late summer – autumn, but in cold climates it can be kept refrigerated (not frozen) and sown in spring. The seeds are highly perishable, and must be kept in the refrigerator3. Propagation from seed is a slow process. Sow the seeds in late summer to autumn, in warm climates, or early spring in colder regions.
Seed should be sown in deep (10 cm) trays, in a mixture of equal parts river sand and fine compost, and kept semi-shaded and moist. Fresh seed germinates readily within 6 to 8 weeks2 but can take up to 3 months1. Germination can be erratic: between 30 to 90 days. The majority come up at 30 to 50 days, but don’t throw away the pots too soon, you may have a couple of “latecomers” 3.
The seed should be sown thinly as the seedlings will stay in the tray for their first year. Seedlings should be potted up into individual containers during their second year and can be planted into the garden or permanent pots in their third year. Flowering can be expected from their third or fourth year2.
Soil temperature should be kept higher than 15°C / 59°F to ensure good germination.Plant in winter or spring, taking care not to damage the fleshy, brittle roots 1.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Blue Triumphator is a half hardy plant.1 The Flower Expert: Agapanthus
2 Agapanthus praecox on PlantzAfrica
4 :The South African Gardener’s Survival Manual; first published 1985