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IGTV chat with John Wyer about Roof gardens

Nicola Gammon, CEO, Shoot and John Wyer, Bowles & Wyer discuss roof gardens and John answers questions from from Shoot members.

IGTV on Roof Gardens from Shoot Gardening on Vimeo.

Some of the questions John answered today from our community include:

Catherine Horwood Barwise (Author of Beth Chatto. A Life with Plants. European Gardening Book of the Year 2019.)
“I find watering systems really challenging and usually water by hand. Any advice?”

Camilla Grayley Garden Design:
“which suppliers do you recommend for intensive roof soils?“

May Nel: student at Capel Manor College

“Large balconies eg office balconies or flats of about 65m2 in London- not on top floor - often shady and windy - most articles I read talk about drought resistant sun loving plants, but what about the the dark, cold terraces that are in part to full shade? What trees, shrubs and perennials do you recommend?”

Rick Laughlin, APLD USA
“Contractor contacts for NYC would be helpful!”

Johanna Norlin
“Would be great to hear John's view on weight loading capacity for roof terraces. Most roof terraces, even new built, have very low weight loading restrictions, which means you can hardly put anything on them not even light weight planters with moist soil and plants fall within the limitations. How do you deal with that?"

Marlene Lento: GreenOak Services


  • What is one of the things that you wish you would have known when you at first started designing roof gardens?


  • Can you elaborate on the make-up of the compost you recommend for roof garden planters?
  • Is there additional advice for feeding plants than there would be in a regular garden?
  • What are some good ornamental trees that can be used on roof terraces?
  • Are there plants (other than agapanthus) that will enjoy having their rootballs restricted?

Screening for privacy, sun and wind

  • What are the options for using plants for visual screening apart from bamboo, grasses and instant green screens?
  • What other kinds of screening ideas are there people may not have thought about?


  • Do you have any clever ideas on storage and what would you usually have to include storage for that a client may not have considered (apart from cushions)?

Heaters for roof terraces

  • Considering gas bottles might be cumbersome to change, what type of heating do you recommend and what do you need to consider?


  • What do you need to consider when anchoring elements to the roof or parapets so water-proofing doesn’t get compromised (e.g. pergola), or what other options for anchoring are there (weighting etc.)?


  • Establishing a water supply for a kitchen- what to consider about drainage for sinks on roof top kitchens, can this be discharged into rainwater drain?


  • are there different types of irrigation systems, how do you turn them on, what does automation involve?
  • How can you create an irrigation system that serves planters all around a roof terrace and is visually unobtrusive, especially if you have central planters and no raised decking?


  • What are the restrictions on what you can put onto roof tops other than physical restrictions?
  • Will these be imposed by the landlord or the local authorities, i.e. is it ok to install a BBQ wherever you want, even if it isn’t a charcoal BBQ? How do you find out?

Installation/ craning and contract lifts

  • Do you have any tips for the logistics of installing a roof terrace project that requires a crane (other than being organised enough to have everything you want to go off and on the roof on the day ready)?

Safety/ Critical fall height

  • Often, existing railings are unattractive and would benefit from being replaced with planters or other fixed or heavy elements. Are there any suggestions or warnings around this (other than that these balustrade replacements need to be heavy and prevent falls.
If you still have questions then please book onto John's Development Day with the Society of Garden Designers on roof gardens.
By Bowles & Wyer

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