Growing out

Plants are grown out (usually under glass) for four reasons: harvesting fresher or more seed; identification; research; and display.

Plants growing out in the Millennium Seed Bank glasshouse (Image: RBG Kew)

If viability of a stored species falls to below 75%, seed may be grown out to harvest fresher seed, in a process known as 'regeneration'. Where a species in Kew’s Millennium Seed Bank (MSB) is poorly represented or has very low seed numbers, seed may be grown out to harvest more seed, known as ‘multiplication’. This process is usually used for species that are rare UK natives, but may also be applied to overseas species such as Cylindrophyllum hallii from South Africa which is critically endangered in the wild. Plants are being grown in order to increase seed numbers. The plant material will be distributed to other ex situ conservation organisations (if the Access and Benefit Sharing Agreement permits this) and will be used to develop a propagation protocol.

Material is also multiplied for re-introduction into the wild. To date these have been mainly UK native species such as Damasonium alisma (starfruit), Corrigiola littoralis (strapwort) and Apium repens (creeping marshwort). This work has primarily been in support of Natural England's Species Recovery Programme. The MSB Project has also been involved in the successful propagation of plants of Silene tomentosa from Gibraltar, a species thought to be extinct in the wild. Plants were grown from seeds stored in the MSB and using the knowledge gained from this process, plants have now been successfully reintroduced to the Rock of Gibraltar.