Following the recent Met Office Red Extreme Heat Warning, as temperatures build this week in much of England and Wales, we take a look at the impact of such extreme hot weather conditions here in the Botanic Garden & how we look after our plant collection during such periods.
How our Horticultural Team work
Our Horticultural team often come in earlier during periods of hot weather to get essential watering done before the heat of the day. This is especially important for the Glasshouse Team.
The team get the glasshouses ventilated as much as they can and try to get a good air flow through, to cool them down. They’ll then water the collection again later in the day, damping down the paths to maintain the humidity in order to take the temperatures down.
The whole horticultural team often start work earlier during period of hot weather. They also aim to work in the shade as much as possible, especially from 10.30am onwards. They all take regular breaks and always carry water with them to avoid heat stroke.
The most popular jobs in the shade!
“Weeding through the woodland is a particular hot weather favorite” says Paul Aston, senior horticulturist, CUBG, “but there are also jobs behind the scenes such as in the shade tunnel where we grow on our woodland plants.”
Our horticultural team use such times to check our plant collection. They regularly bring samples of plant material indoors to verify that they match up with the names they are labelled with. It’s also a good time to audit the beds – checking which plants are in them during the early cool of the day and then updating this on our plant database when it becomes too hot to work outside.
Another cooler job is the repotting of dormant bulbs. Spring flowering bulbs are put into fresh compost, audited and checked through for pests and diseases.
And there is always pot washing to fall back on! We re-use all of our plastic pots and lots are still piled up ready to be scrubbed after the spring mass plantings. The pots are soaked and washed in a large tank of cold water – lovely to put your hands into on a hot day, so it’s always a popular job!
Our planting strategy & the living collection
Sally Petit, CUBG Head of Horticulture says “For some time we’ve considered our climate and the Garden environment and how that can help us mitigate against dry, hot conditions. We have very well-drained soil and low rainfall here, which means that generally our collections aren’t grown too lush, & as such are more resilient to extremes.”
“We are concerned about the potential impact of hotter, drier weather on our living collection, which we grow for teaching and to support scientists and their research worldwide” says Beverley Glover, CUBG Director. “This research includes tackling some of the world’s greatest challenges such as climate change and food security, for example, so it’s vital our collection is well maintained and looked after.”
How we encourage plants to be more drought tolerant
This year we’ve been holding off watering until necessary to try to avoid plants growing too lush. We’ve been prioritising watering to establish new plantings such as those in our Autumn Garden and plants showing signs of stress. We’ve also been watering more in the Glasshouse Range and watering earlier in the day.
We always aim to try to get plants to root as deeply as we can earlier in the year through puddling in the plants when planted out, and then leaving them for a few weeks. When they have almost dried out, we water them very thoroughly again. This process is then repeated until they are established. Regular, light watering tends to encourage roots to form near the surface, rather than to grow deep down searching for moisture. Such surface roots are much more prone to drying out and plants become more water dependent.
Any irrigation is set up and turned on overnight. Seep hoses are increasingly being used in our new plantings, which get the water down to the roots in a much more sustainable way.
“The same strategies can be used at home in any garden to encourage plants to be more drought resistant. Water thoroughly when plants need it, rather than frequent, light watering and aim to water first thing in the morning or late in the day when the temperatures are lower” is Sally’s advice.
Inspiration for your own garden
Our Mediterranean Beds, Dry Perennial Meadow and our Dry Garden are good examples of drought tolerant planting. The Dry Garden is designed for the weather which is causing so many of our garden plants to struggle. It was developed to demonstrate low water or no water gardens – it hasn’t had any supplementary irrigation since it was planted 20 years ago.
Gardeners can use these areas for planting inspiration. According to Sally, the key is ‘to plan, think about what you want to grow, see what’s available and what’s suitable. Think ‘right plant, right place’. Generally speaking, plants with grey leaves, hairs leaves, slender leaves, leathery or succulent leaves and blubs have evolved to withstand extreme heat and long periods of little rain.