There are many different ways you could plant the green roof of The RHS Garden Retreat. So we asked the RHS to devise green roof planting schemes, especially for The RHS Garden Retreat.
They came up with three schemes and in addition, an easy maintenance option. These schemes are perfect for a shady spot, full sun or even a windy, coastal location together with a low maintenance option.
Low Maintenance Green Roof Planting Schemes
If you would like a low maintenance green roof you can in fact buy a ready-made Sedum mat. Ready-made Sedum mats are available to buy and can be rolled out onto the roof once the planting medium has been prepared.
Planting the Sedum Green Roof
The Sedum mat should be planted in a 5-15cm (2-6in) depth of growing medium. This can consist mainly of lightweight, inorganic materials such as perlite, leca, sand, rockwool and crushed tiles or concrete.
Please follow the Sedum mat manufacturer’s instructions on the growing media and planting the Sedum green roof.
Maintaining the Sedum Green Roof
Watering plants during establishment will ensure that they root out thoroughly. Once rooted, the Sedum roof is fairly maintenance free. This is except, of course, for watering in prolonged dry spells and some occasional weeding.
More Varied Green Roof Planting Schemes
Do you have a shady spot or would you like a more varied green roof? These will be higher maintenance but if you are keen, read on for a few suggestions for planting schemes that would work well.
Woodland Shade Planting
These plants should establish well in woodland shade settings:
- Epimedium × rubrum
- Alchemilla mollis
- Brunnera macrophylla
- Euphorbia amygdaloides var. robbiae
- Galium odoratum
- Geranium macrorrhizum ‘Bevans’ Variety’
- Lamium maculatum ‘White Nancy’
- Vinca minor – any cultivar
Dry Sunny Planting
For dry and sunny spots, these varieties should fare well.
- Achillea ‘Terracotta’
- Potentilla alba
- Armeria maritima ‘Splendens’
- Dianthus deltoides
- Helictotrichon sempervirens
- Stipa tenuissima
- Muscari armeniacum
- Allium flavum
- Allium pulchellum
These varieties should suit coastal locations.
- Achillea millefolium
- Armeria maritima
- Centaurium erythraea
- Euphorbia portlandica
- Festuca ovina
- Festuca rubra subsp. rubra
- Plantago lanceolata
- Sanguisorba minor
- Scilla verna
- Sedum acre
- Sedum anglicum
- Silene maritima
- Thymus praecox
- Trifolium arvense
- Veronica arvensis
Planting the Woodland Shade, Dry Sunny or Coastal Plantings
The plants should be used as a mix, with 9-12 plants of 9cm (3.5 inch) pot size per square metre of the green roof in 15cm (6 inches) of growing medium.
The RHS suggest using a loam grit based peat free compost, such as Sylva Grow® John Innes no 3 compost, with horticultural grit added to make up 20% of the mix.
Maintaining the Woodland Shade, Dry Sunny or Coastal Plantings
Firstly, watering the plants during establishment will ensure that they root out thoroughly. Then keeping them regularly watered as you would the rest of the garden will keep them looking healthy.
Cut back herbaceous plants in late March when the new growth is pushing through. The seed heads can look attractive during the winter months and prove valuable habitats for over-wintering insects. Finally, apply a balanced fertiliser every spring to maintain nutrient levels.
Health & Safety
Take care when working at height and using a ladder when planting The RHS Garden Retreat green roof.
Seek the help of a professional for the planting and maintenance of the green roof if you have any concerns.
These planting plans are devised by the RHS specifically for The RHS Garden Retreat. They should not be used on any other green roof without seeking professional advice.
The RHS Garden Retreat green roof is designed for using up to 15cm (6 inches) of growing medium. A maximum weight of 1,000kg can be supported. Please do not exceed these limits.