As well as growing in traditional herb gardens, in Britain, Monarda is probably most commonly seen in the ornamental garden, although they’re also ideal for wild gardens and meadows, including using the prairie gardening styles. The use of Monarda in this way has been helped to become popular by Piet Oudolf, who himself developed a number of the modern cultiars. The smaller forms such as Cranberry Lace also make great outdoor pot plants. They are of course perfect for all types of herbaceous bvorder, with many growing within the height range of 90 to 150cm. Similarly, with colours from white and the spectrum of reds, pinks, purples and violets, they will fit into many planting schemes.
They ideally need full sun or light shade, spaced around 50 cm apart, preferably with some compost mixed into the soil. Most of the forms shouldn’t be allowed to dry out, so a moderately and consistently moisture retentive spot is needed, but in most cases not boggy. Varieties do vary though, with some being more able to cope with a wider range of moisture levels. This is particularly so for the more modern cultivars, which are often fistulosa and didyma hybrids; fistulosa itself growing naturally in drier locations. It’s sensible to mulch annually. Although perhaps an extra chore, in this case it’s important to help the soil retain moisture; also helping to reduce stress in very dry summers. Remove spent flowers if yours is a very tidy garden or, given the right weather, consider pruning flower heads for possible second blooms in you’re very lucky. Regarding cutting back growth, either leave the dead stems overwinter for ‘architectural’ effect and to provide plant material for wildlife, or cut down to the ground every Autumn. Dig up and divide the plants preferably every three years, either in Spring or Autumn, discarding the centre portions. This not only keeps them looking good, but it also helps reduce the risk of powdery mildew as well as maintaining a strong plant.
Well known as being susceptible to powdery mildew towards the end of summer, as well as sometimes fungal leaf spot, there are some well-tried methods to help reduce the problem, although the best way of all is to grow newer mildew resistant varieties such as ‘Gardenview Scarlet (red), Marshall’s Delight’ (pink), ‘Violet Queen’ or ‘Raspberry Wine’ . For other cultivars, don’t use high nitrogen fertiliser, don’t let the soil dry out, prune out stems to keep airflow moving and if watering the plants, water at the base only or water when the leaves will dry quickly. It’s also a further reason to plant in full sun if possible. Powdery mildew itself does not kill the plant directly, but it can seriously affect its vigour and therefore its longevity. Many gardeners of course dislike it for the way it ruins the plant’s splendour. It’s sensible to remove and burn the diseased plant material in order to destroy the fungus overwintering in situ. The use of fungicides, including ones safe to wildlife may be considered if necessary. High humidity makes the problem worse.
Propagate by root division works very well in early spring or autumn, or by separating and replanting the stolons. Growing from seed from early spring works well if you don’t cover the seeds, keep at 15-20˚ C and keep moist; perhaps by covering in cling film, until germination occurs. Bottom heat also helps. Germination time can be as little as less than a week with this method, although much longer is to be expected if sowing in situ or if not using a heated propagator. Hardwood or softwood cuttings can also be taken.
Harvest leaves for drying before the flowers open and cut flowers for drying immediately they open.