Back in September 2018, I arrived at the Millennium Seed Bank in Sussex with a real sense of excitement.
I was there for a residential course on Seed Conservation Techniques. My 13 course mates had travelled from all corners of the world, including Poland, Oman, Singapore, New Zealand, the US and Colombia. I felt very fortunate to be there and I was delighted to be in the company of people so passionate about plant conservation.
The Millennium Seed Bank Partnership, run by the Royal Botanic Gardens, Kew, is the largest seed bank in the world for wild plants, conserving 2.4 billion seeds from more than 39,000 plant species.
During the 3-week course, we learned from the experts all about seed science and conservation. We developed new skills, experience, collaborations, friendships, and since then, we have each worked on developing seed banks in our home countries.
A seed bank for the Welsh flora had been a long-term vision at the National Botanic Garden of Wales and in 2018, we started on the journey to make it happen.
Safeguarding plants in seed banks
Recent global estimates suggest that up to 40% of plant species are threatened with extinction. This is not only worrying for those plants, but also for all the biodiversity, such as butterflies, bees and fungi, that depend on them.
Seed banks are a key tool to help conserve plants for the future. By storing seeds long-term, they act as an insurance policy helping to avert plant extinctions – if a population of a plant reaches a crisis point, seed can be taken out of storage and grown to produce plants for reintroduction or habitat restoration.
The Millennium Seed Bank stores seeds from around the world and this includes seeds from nearly all of the UK flora, from at least one population per species. You may wonder, then, ‘why we are setting up a seed bank in Wales’? The reason is to help safeguard genetic diversity.
Genetic diversity holds the key to species’ resilience and adaptation in the face of environmental changes. The more genetic diversity a population holds, the more likely it is to survive challenges such as climate change or attack from new pests and diseases.
Even shrinking populations or local extinctions are a concern as this gradually erodes genetic diversity. This was the case for meadow clary (Salvia pratensis), which became extinct in the wild in Wales due to inbreeding at its only Welsh site. The Botanic Garden collaborated on a project to reintroduce this rare plant to its former home in 2016, by crosspollinating Welsh seed with seed from other UK populations.
The more seed collections banked for a species and the wider geographic area they come from, the more genetic diversity is captured and the better that species is conserved for the future.
We’re focussing on species that do not yet have Welsh-origin collections at the Millennium Seed Bank – as of 2018, that was around 75% of Welsh plant species.
So far, we’ve banked seeds from 34 different species – this blog by Elliot Waters, Biophilic Wales Conservation Assistant, introduces some highlights.
A new seed bank for wild Welsh plants
Two labs in the Science Centre at the Botanic Garden are now home to the National Seed Bank of Wales. We have gradually set up the labs to allow us to conserve seeds to international standards.
If you have been on a Growing the Future course, you have helped! The course proceeds have helped to fund the specialist equipment.
What’s involved in seed banking?
After some desk research—to identify target species, field sites, seeding times and to secure collection permissions—we visit sites in Wales with the aim of collecting 10,000 seeds per population. Locating these species is easier for some than others! It’s always a huge help to link with local experts like local conservation rangers or recorders from the Botanical Society of Britain and Ireland.
Once a target species has been located, we assess the population size, seed maturity and seed quality. All going well, we collect seed and record field data. To make sure our seed collecting does not damage populations, we collect sensitively – a maximum of 20% of the available seeds, reduced to 10% for threatened species.
Back at the Botanic Garden’s Science Centre, the seed is taken to the seed processing lab. There, it is carefully cleaned and dried. The cleaning techniques vary depending on the species, but it tends to involve low-tech methods like sieving and we also have aspirators that use air currents to separate seeds from the chaff.
The seed is then dried to 15% relative humidity in incubators. This drying stage minimises the risk of ice crystals forming inside the seeds during storage, while retaining enough moisture to keep them alive.
The dry seed is then taken to the seed storage lab, where it is sealed in special air-tight foil pouches and stored in freezers at -20oC. This low temperature slows the respiration and lowers the rate of aging.
Half of the seed in each collection is stored in our new seed bank facility and the other half is sent to the Millennium Seed Bank.
As seed banking is an evolving science, it is not yet known exactly how long seeds can stay viable. This will depend on the species, but seeds of many could stay viable for 100s of years. To check how the seeds are storing, germination tests are done periodically.
Working together with colleagues, I’m really looking forward to making more seed collection trips, conserving more Welsh plants and seeing the future conservation uses of these seeds.
We’re thrilled that some of our recently collected seed is already contributing to a conservation project on the ground – a small batch of goldilocks aster (Galatella linosyris) seed collected on the Great Orme was dispatched in spring 2020 to help with a reintroduction project in Cumbria.
Looking for wildflower seeds for your garden?
You’re in luck! Sustainably harvested seeds from our organic farm at Waun Las National Nature Reserve are now available to purchase. Sales help to fund the Botanic Garden’s charitable work, such as the seed bank.
For geeky guides on saving and storing seeds at home, see here and here.
The seed bank is a collaborative project between Growing the Future, Biophilic Wales and the Horticulture and Science Teams.
We are extremely grateful to the Millennium Seed Bank for providing training and continued technical support and guidance.