TREE seedlings in indoor vertical farms have been found to grow six times faster than in traditional outdoor settings.

A Scottish trial found the trees could reach up to 50cm in about 90 days. A similar level of growth could take up to 18 months in a field.

Forestry and Land Scotland (FLS) ran the study with Intelligent Growth Solutions (IGS), an agriculture technology firm.

Forestry Journal: Species included Norway spruce Species included Norway spruce (Image: FLS)

Kenny Hay, the tree nursery and seed resource manager at FLS, said: “Climate change is leading to unprecedented threats to our forests, including rising temperatures, prolonged drought, increased pests and wildfires. For example, millions of larches have been lost in the last few years in Scotland alone, due to the fungal disease, P. Ramorum.

“Planting more trees – both for timber and biodiversity benefits - is vital if we are to tackle the twin crisis of climate and biodiversity. The urgent need to do so much, quickly, to mitigate climate change means that existing processes and supplies of high quality tree seed are under significant strain.

“A vertical farming system for growing trees could allow us to grow many more trees – faster, more efficiently and with far less water - for planting out into the future forests of the UK."

FLS manages about 630,000 hectares of forest and land owned by the Scottish government, and plants about 24 million trees annually. It believes indoor farming could help its ambition to plant even more trees around the country.

Vertical farming typically involves plants being grown in large trays using artificial light. The practice is gaining popularity in urban centres and other areas around the world, although it has mainly been used to grow simple salads and herbs.

Five trials involving trees took place at the IGS Crop Research Centre in the James Hutton Institute at Invergowrie, near Dundee. Tweaks to the environment were made each time to improve yields, with different light settings, nutrition and watering.

Forestry Journal: Kenny Hay has hailed the results of the project Kenny Hay has hailed the results of the project (Image: FLS)

Vertical farms use less water than polytunnels or glasshouses require. Specimens grown have included conifers such as Norway spruce, Douglas fir and Scots pine as well as broadleaf varieties such as oak, alder, birch and hazel.

The research also suggests germination rates are more efficient. All of the seedlings have been transferred and adapted to outdoor conditions.

A sixth trial now underway and will aim to actually slow the growth rate down to get thicker root collars on the seedlings, which will make them more suitable for planting out in restock forest.

David Farquhar, the chief executive of IGS, said: “We believe vertical farming has a real role to play in supporting reforestation projects all over the world and this is a very exciting step towards making that a reality.”