Friday, 14 September 2018

Gardening in a heatwave

I recently wrote a post explaining what all the effects of Climate Change will be and included this point about agriculture:

"Drought, flooding and changes in seasonal temperatures will mean farmers having to cope with either too much or too little water and increased levels of pests and diseases.  These negative effects on agriculture will result in increased food prices globally, food shortages and more famines."

As we bid farewell to the heatwave summer 2018, where temperatures rocketed and rain was almost non existent it seems like a good time to assess how one hot summer affected my vegetable garden at Eco-Gites of Lenault and consider how the heat will have affected farmers.

The Polytunnel


  • Early tomatoes - those tomatoes I got in early did well but as temperatures rose things changed - see below.
  • Peppers, chillies and aubergines - the best year ever for these. They loved the heat and without a need for excessive water I could easily keep them going.  They are still cropping well now.
  • Early crops - very early potatoes, early greens/lettuces etc all did well, protected from the cold spring winds and were harvested before the heatwave arrived.


  • Later tomatoes - as temperatures rose, fewer tomatoes set fruit. Research has shown that with night temperatures above 21°C and daytime above 30°C fewer tomato flowers successfully fruit as the pollen becomes too tacky.  This year daytime temperatures in the polytunnel were often above 40°C so it is no wonder I had fewer tomatoes ... and those I did have were smaller than previous years with more blossom end rot - both a result of water shortages. I watered as much as I could but tomatoes are water-hungry plants.
  • Melons and Butternut squashes - both these were a complete failure in the polytunnel with no fruits at all.  I did manage to get a few small watermelons but they didn't have much flavour.
  • French Beans - I usually have some lovely early French beans from early undercover sowings but this year the pods quickly became tough as the plants were stressed in the excessive heat.  
  • Late July sowings - I sow a variety of crops such as turnips, chard, more French beans and beetroot to mature through the autumn but almost without fail these died - it was simply too hot for seedlings to survive. 

Vegetables outside


  • Pumpkins - I am yet to harvest these but a sneak preview under the leaves indicates a bumper crop, including the butternuts that failed under cover.  These were grown entirely without water, through weed suppressing fabric that does help retain moisture.
  • Courgettes - another bumper crop grown through weed suppressing fabric but the success was only because I watered them a lot.  Without water, the plants showed rapid signs of wilting.


  • Beans - I simply could not get enough water to the plants and had very poor crops of Runner and French beans.  I am luckily getting a few more from a late sowing I managed to keep alive with a lot of watering.
  • Maincrop Brassicas - cabbages, broccoli, Brussel sprouts. These were practically all a total failure. It was too hot for them and then all succumbed to a plague-like infestation of flea beetles. Leaves that were left damaged after the beetles feasted on them just burnt off in temperatures that registered 37°C in the shade ... and they were in full sun where it was even hotter. I had to pull all the plants up in the hope that I could stop the beetles moving to the younger and even more vulnerable late kale.  I am hopeful I will get at least some greens from these although they are still much smaller than I would expect at this time of year.

Fruit Garden and Orchard

Summer berries

  • The biggest problem with the summer fruit was not a poor harvest (I would say it was better than some years) but that all the fruit ripened very quickly and at the same time. I lost some fruit that became over-ripe in the heat before I was able to pick it.

Autumn berries

  • With the heatwave over I am now having the best crop ever of autumn raspberries and blackberries. I do not know if this is linked to the earlier high temperatures.

Tree fruit

  • Our apple crop was smaller, both in numbers of apples and their individual size but the pears on the tree against the house are looking good.  One damson tree had almost no fruit and the other was laden.  Overall the trees have not done well and are losing leaves earlier than expected.


If hot summers like this become normal I will need to reassess how I garden. Ideas that might help include:
  • Collect even more water in wet periods to reduce using metered water. This would become even more important were hosepipe bans to be put in place and save money (I am dreading my next water bill).
  • Keep adding manure to the soil to increase its water retaining properties.
  • Use more mulches to retain moisture - I usually use grass clippings but had less grass this year as well! Other options include cardboard, mulched leaves, woodchip, seaweed and straw.
  • Grow some tomatoes outside (and hope we don't get a wet summer when blight will kill them!)
  • Try and sow earlier or later in the season although our recent colder springs have made early sowings harder.

Overall I will have harvested enough to mean I won't need to buy too many vegetables.  I will have to buy winter brassicas but thankfully other plants I have not mentioned here have been good enough to feed a family of 4.  But what about farmers growing on a much greater scale for the public? How has the heatwave affected them? My farmer neighbour said his wheat crops were well below average and with so little grass he has been giving his cattle additional feed.  I suspect vegetable farmers will have seen lower crop yields and will only have achieved these with extra watering and chemical applications against pests.  It may be that the next heatwave won't be for many years but overall climate is changing and is not predictable. This makes it hard for farmers to plan for successful harvests and can result in lower harvests and so higher prices in the shops.  Also, if local farmers cannot supply enough then we must rely on imported foods which is good for neither our pockets nor the environment.

Do you grow fruit and vegetables and if so how did your garden fare this summer?


  1. Good overview. It is interesting to me that many of the same pressures you felt were the same as we saw here in Ontario, Canada. I had the same bumper crop of certain fruits like raspberries but all coming ready in a very short time requiring daily picking of two or more hours.

    Thankfully we have had a good hay crop this year and most of the grain crops got in at the right time and the corn looks like it will be a above average yield.

    My permaculture style gardens with their deep cool covered roots with lots of compost out produced any plants done in a more normal style garden plantings.

  2. I am in South West England. I don't grow vegetables but I lost quite a few plants this year. We had heavy snow in March and then a hot dry summer. The winners were the Michealmas daisies which are in full flower now and my pots of geraniums.
    Big losers were gladioli and Irises.

  3. Somw of my mum's tomatoes didn't make it in the heat we had, hope the heatwave does continue so we can enjoy it but need to re-look at our garden

  4. It's sad to think how to reevaluate your gardening based on climate change! But it's good to see that you are making it work and growing such beautiful crops. Hopefully next year will be similar and not more shocking with the changes that occur from our actions on earth.

    Addie // Old World New

    1. Thank you Addie - it is easier for me, as a gardener, to make changes to adapt to any changes in climate - much harder for commercial producers, though.

  5. Gardening when the weather is so hot is a pain. I am happy we have some rain now.

  6. We don't grow much but noticed our strawberries did well but the tomatoes just didn't thrive and I have no idea why

  7. This was really interesting to read. The weather changes how we grow things so much doesn't it. I wonder if we will have another heat wave like this or whether we will go back to wet summers next year

  8. I started my garden off really well with lots of tomato plants, lots of strawberry plants, a raspberry bush and a blackberry bush. The only thing I actually got anything off was the blackberry bush, and even then it was only a couple of berries. This year was a complete fail for me. Last year I did much better and grew potatoes, carrots, beetroot, kale, spinach, lettuce, tomatoes and berries but no such luck this year!


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