If I had a pound for each time I heard somebody say “Well it’s climate change isn’t it?” either because it’s unusually hot, cold, wet or dry I’d be rich. Of course each of those weather scenarios is connected to climate, so all uses of the phrase are correct. As gardeners we are much more aware of the weather than most people because we are generally living day to day through the health and yields of our plants (be that flowers, fruit or vegetables).
We’ve had quite a cloudy spell of below average temperatures in July 2017 and it’s affecting my pumpkins (they’re not fruiting as much which is not great for my giant pumpkins which tend to fruit later than the rest). The sunflowers seem to have gone to sleep and the courgettes and sweetcorn with them. Honestly it was a bit of a relief with the courgettes! It’s also been unusually wet which has increased cases of tomato blight through humidity, encouraged white fly in my greenhouse and mildew on my Dahlias.
From a gardener’s perspective I thought it would be interesting to examine weather and temperature trends locally this century, specifically looking at data from local semi-rural weather stations in Surrey & West Sussex. My allotment is semi-rural so during the cold seasons I need to know if the temperatures are going to drop more significantly than in a town. In towns and cities, buildings and roads retain more heat at night and concreted roads reduce evaporation which would otherwise cool temperatures more quickly (hence it’s colder in rural locations).
Looking at average weather station data from Crawley Down (on the outskirts of Crawley in West Sussex) I extracted their annual records manually and generated the resulting trend graphs myself. The outcomes displayed at the bottom of this article show that since 2000:
- Precipitation is increasing i.e. on average it’s getting wetter each year.
- Heavy precipitation days (days in excess of 20mm) are increasing in frequency.
- The highest average temperature is falling (a little).
- The lowest average temperature is dropping (a lot).
- The average temperature is falling marginally i.e. it’s getting colder each year.
Now of course climate change scientists tell us that globally temperatures are rising and we’re at risk of droughts, but I’m not growing globally I’m growing locally. If this is how global climate change is going to affect our part of the world we need to know about it and plan accordingly.
Averaging out these local weather trends it’s going to be getting wetter and colder over the next decade in Surrey and West Sussex with increased heavy rainfall events and overnight hard frosts. That’s good news for golf course managers and water companies but bad news for those of us growing crops like tomatoes, chillies or pumpkins. It’s probably not great news for local arable farmers either.
Preparing the allotment for wetter and colder weather:
There are some steps that can be taken to make an allotment or vegetable garden more suited to a colder and wetter climate:
- Use raised beds to grow crops, raised beds will drain more quickly and not hold water which when standing can rot root crops or alliums / onions and/or increase diseases like club root in cauliflowers.
- Fertilise beds more regularly because the excess precipitation will wash away the nutrients plants need to grow.
- Be prepared to cover fragile crops with grow tunnels at short notice to protect them from unexpected heavy rain or hail incidents.
- Learn to love cold weather crops like Brassicas (cabbages, Brussels sprouts, broccoli), potatoes, swedes and carrots.
- To reduce ‘rust’ grow leeks in small spread out groups across your plot not in rows (this also helps stop the spread of Allium Leaf Miner / ALM).
- Install a polytunnel or two to provide additional heat for the warm climate plants like tomatoes. Polytunnels also provide additional protection from blight.
- Obtain one or two water butts to gather all this excess water for use in your polytunnel(s).
- Expect higher slug populations and encourage toads and frogs into your plot top eat them (perhaps add a pond), this is a much better solution than increasing use of wildlife harming slug pellets.
- Dig drainage ditches along the sides of your plot if flooding is becoming a problem, most likely on heavy clay allotments like mine…
- Plant more fruit trees to help retain top soil and prevent it from washing away into rivers and streams.
Here are the graphs showing the data recorded by the Crawley Down Weather Station. I have added in trend lines with projections for the next decade to 2027 should rates of change continue as they have since 2000.