How to plant Osmunda
Osmunda are attractive, deciduous ferns, providing an architectural presence in summer before the autumn fronds transform to russet shades of gold and orange with the first frosts. This genus includes one of the largest hardy ferns, Osmunda regalis (Royal Fern) which can produce fronds of up to 3m at full maturity, although in most garden conditions it achieves a more modest height of around 60cm. These majestic ferns flourish in shaded spots, preferring cool, damp positions in shade or close to pond-edges.
How to plant
- Plant Osmunda in spring between February and May, ideally within a week of delivery.
- Soak the roots in water for 3-6 hours prior to planting. Pot into temporary 2 litre (or 15-20m diameter) pots, using a good quality multi-purpose compost.
- Plant so that the roots are fully submerged in the compost crown/buds just level with the soil surface. Any emerging shoots or leaves should be left exposed above the soil surface.
- Grow them on in a sheltered spot outside. They can be into a suitable final growing position in a border after around 2-4 months, once growth is established and the plant is easily removed from the pot with the soil held intact by the roots.
- Osmunda prefers a reliably moist neutral to acid soil, however it can cope on more alkaline soils where plenty of well-rotted compost has been added.
- Choose a position in dappled shade or full shade. Osmunda can be grown in sunny positions where the soil remains moist in summer, such as bog gardens and the damp soil at pond edges.
- They are winter hardy, but prefer a sheltered position away from strong winds.
- Water-in after planting and keep hydrated when in growth, particularly during the first year.
Aftercare
- Fronds emerge in spring and last through summer. The foliage transforms to orange and gold in autumn before turning brown for winter. They can be cut back in autumn or left intact throughout the winter to provide interesting winter architecture. Cut back old fronds by early spring to clear space for emerging new growth.
- Once established they need very little maintenance but will appreciate an autumn mulch of leaf mould. Avoid covering the crown of the plant with mulch as this may lead to rotting.