Ask Our Grower

Ask Our Grower

24th March 2015

Vince Wheller is regarded by Sky Garden as a leading expert in growing vegetation for green roof systems.

His wide knowledge of growing does not stop at green roof systems. Vince began his growing career with fruit, managing a large fruit farm selling thousands of tonnes of fresh fruit to the UK supermarkets. He then ventured into his own farm business, starting with fruit but moving into sedum in 2008.

Fortunately for us, Vince joined Sky Garden in 2014 and has been in charge of growing our very own, high quality sedum and wildflower plants for our green roofs.

We often receive questions from past, current and potential customers about our plants, and so we thought there is no better person to answer these questions than Vince himself:


Is sedum difficult to grow?

Sedum isn’t hard to grow but requires the correct materials and maintenance to allow it to flourish on a roof. The roof is a harsh environment; cold, windy, extremes of wet and dry. Sedum is perfectly suited to these extremes but without a well designed free draining roof it is easy to spoil sedum.

How long will a green roof last?

A green roof should extend the life of the waterproof membrane by eliminating UV. The longest surviving sedum roof on record in Austria is over 70 years old. If the roof is installed correctly then sedum will keep regenerating itself. A little maintenance and a light feed will keep it looking great for many many years.

What and how often should a sedum roof be fed?

No fixed routine here, deeper substrate requires less feeding. Once or twice a year with a light sprinkling of an organic green roof fertiliser will suffice.

Can I walk on my green roof?

Yes for a maintenance treatment but sedum is not as resilient as grass to foot traffic and bruises easily. If walked on regularly it will start to wither away

How often do green roofs need watering?

Sedum is drought tolerant and once established will usually survive the full year without the need for irrigation, but there are some exceptions. On a pitched, sloping or barrel shaped roof the excess water will drain to the lowest points and may require irrigation from the top. An extremely dry or extended dry spell may require irrigation. If you irrigate during dry spells you should avoid the sedum turning red and showing stress

Do I have to weed my roof?

Weeds will become established in a sedum roof because you have provided a growing area. Weeds will struggle to survive if you don’t have the growing medium too deep. A quick pull out before they become established or a quick dab with a weed wiper will soon sort them out. Alternatively a maintenance visit can tidy up the sedum and keep it looking great

Why is my sedum red?

Sedum changes colour with the seasons, It often naturally turns red during late Autumn and Winter. If it turns red during the Spring or Summer it is usually a sign of stress where the plants are struggling a bit. This could be too much water, poor drainage or blocked outlets, too little water extended dry spell (irrigation required), or short on nutrition and a light feed is required. But colour changes are normal.


A big thank you to Vince for answering those questions.

If you have a green roof question that needs answering check out our FAQs page. Also, feel free to contact us via email, or write to us on our Twitter or Facebook page with #AskVince.