‘Penhill Dark Monarch' is a sumptuously coloured dinnerplate dahlia, similar in form but deeper in colour to the paler ‘Penhill Watermelon’. Penhill dahlias are known for their impressive size, twisted petals and blended colours.
In bloom from mid-summer to early autumn, ‘Penhill Dark Monarch’ is a tall, tuberous rooted perennial with sturdy stems and mid-green foliage, its flowers can reach 25cm across (10in) in a swirling mix of peach and dark pink.
Dahlia tubers can be planted outside after frost, or started off in pots under glass in late winter to early spring. Plant them horizontally approximately 12cm deep, making sure the ‘eyes’ are uppermost. Allow enough room between each tuber so the plants can grow and spread to their full size without being overcrowded.
While in growth, provide a high-nitrogen liquid feed each week in June, then a high-potash fertiliser each week from July to September. Stake with canes or brushwood if it becomes necessary. In mild areas, leave them in situ over winter, but protect the crown with a generous layer of dry mulch.
In colder areas, carefully lift and clean the tubers once the first frosts have blackened the foliage and allow them to dry naturally indoors. Then place the dry tubers in a shallow tray, just covered with slightly moist potting compost, sand or vermiculite and store in a frost-free place until planting out again.
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© 2025 Cercis Ltd. All rights reserved | Primrose is the trading name of Cercis Ltd (Registration number: 14521244)
© 2025 Cercis Ltd. All rights reserved | Primrose is the trading name of Cercis Ltd (Registration number: 14521244)