A Bellweather for Climate Change

John Curtis, Director at Ventnor, explains their climate change research.

The expected temperature increase under more catastrophic climate change scenarios is 5^oC, and we have that increase now at VBG. That is why we are able to grow plants outside that are normally in greenhouses elsewhere in the U.K.  

We rarely get a frost and when we do, it is short lived. The fact that we have higher average temperatures now allows us to see into the future of plants in the U.K.  Our microclimate shows us what thrives and what perishes in the coming hotter planet. 

As you walk around VBG you will find plants from around the subtropical regions of the world happily growing here. Look for Aloe, Cistus, Callistemon, Salvia, Olive, Euryops and many more. 

The Victorians started to measure sun intensity here in about 1870 using a sun recorder, a magnifying sphere which concentrates the sun rays to etch or burn a piece a recording strip. 

Chris Watts, a volunteer, still runs a weather station here today recording rain, temperature, wind, and sun intensity for the Met Office. Chris’s VBG data shows that December 2015 was mildest recorded since 1839. 

This dramatic change in temperature is reflected in the Living Collection – the plants that are now able to grow at VBG. 

The Canna Bank has always held the riot of colour possible from the species and cultivars of Canna. Canna are well established in English gardens, they are usually treated as half hardy perennials that need to be lifted and divided in Autumn.

In 2000 we abandoned this practice, in the recognition that at VBG we just don't get the penetrating frosts that can kill a Canna rhizome. Being a forward looking garden, we began experimenting, looking for the logical next step for the Canna role.

We decided upon Hedychium, the Ginger Lily. This was fortuitous, as at the same time a virus was making short work of our Canna culivars and Canna collections all over the UK. Initially we treated Hedychium in the same way as Canna were traditionally grown, cut back in autumn.

We recognised that this wasn't necessary for the same reason as the hard work with Canna was redundant: no frost. So now all our Hedychium, including the very tender H.greenei remain in the ground all year with no apparent damage or limitation to their growth.

We have been looking for the next logical step and in 2012 alighted on Brugmansia as successor to Hedychium, having noted that plants of the beautiful species B. sanguinea have grown as herbaceous perennials in our Walled Garden for many years and can reliably be seen in flower on Christmas Day.

We collected as many cultivars as possible, bulked them up over winter in 2012 and planted these through the Canna Bank in 2013. These were overwintered in situ, and died back to their bases during the winter cold. In spring they begun growing back and are now in flower in October, and should continue to do so right through the autumn.