Preparing for summer in a polytunnel means thinking about everything that will happen during the summer months and trying to get ready, as much as we can, to mitigate the risks and take advantage of the opportunities those summer months will bring.
Now that meteorological summer is technically here, let’s take a look at what we should be doing to for preparing for summer in a polytunnel, so that you can check whether you have everything in place, and how you can learn about what to grow in a polytunnel in the summer.
Sowing for Summer Harvests (and for the Seasons Beyond)
With the right attitude and some hard work, you should be reaping the rewards of your efforts in a polytunnel by the time the summer rolls around.
While you can still continue to successional sow many crops right up to midsummer, and some crops can be sown later in summer too, you should have been preparing for summer harvests much earlier in the year.
There are also, however, some quick growing crops that might be sown in early summer to harvest in just a month or so.
But remember, successful polytunnel growing is not just about sowing and planting. There are other things that you should do to make sure that your efforts meet with success.
Table of Contents
Getting a Polytunnel Ready for Summer Heat
One of the important aspects to preparing for summer in a polytunnel lies in making sure that you, your polytunnel and your plants are ready for the higher temperatures that summer can bring.
If you are constructing a new polytunnel for this summer, then it is important to think about how you can keep a polytunnel cool in the summer.
Positioning and orientation are both important, as are ventilation, and layout, and thermal mass…
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One important factor to take into account is the orientation of the doors. By positioning a polytunnel to take advantage of prevailing summer breezes, you can make sure that there is good airflow through the structure. This will help you to keep cool in a polytunnel through the summer months.
You should also spend some time thinking about how adequate ventilation will be maintained. Are the doors alone enough to provide ventilation through the summer, or should you consider side ventilation too? Asking questions like this is important to prevent problems down the line.
Layout and Order
It is essential to be able to regulate the temperature within a polytunnel – especially over the summer. But in the summer, growers will often find that the space becomes crowded as plant growth explodes.
To keep cool, avoiding stress and hassle, it is important to have a well-worked-out scheme, with good access. This will stop you from getting flustered, raising the heat still further. And it will ensure that you can easily alter ventilation as required.
Another very important thing to consider at the design stage is thermal mass. To keep cool in a polytunnel, incorporate materials with high thermal mass.
These materials, like stone, brick, ceramic and clay, water and soil, are good at catching and retaining the sun’s heat during the day. They then release that heat at night, when temperatures fall.
So they can keep the temperatures more constant over time. They help things keep cool in summer, and reduce issues with cold in the winter months.
Before the summer months, it is a good idea in a new or existing polytunnel to consider also ways in which you can sustainably cool the space during particularly warm spells.
You can, for example:
- Place a tray of water with a rag within it in a breeze. As the water evaporates from the material, it will cool the air of the surrounding area.
- Dry some laundry in the space. This is a good way to kill two birds with one stone. Your clothes should dry more quickly than they would outside, and as the water evaporates from the material, this should cool the space to a degree.
- Increase humidity by spraying paths and hard surfaces.
- Cool your polytunnel with a fan (ideally one powered with renewable energy).
Plants can be negatively impacted not only by air temperatures that rise too high but also by high soil temperatures. So you should also make sure that you take steps to keep the soil cool by:
- Creating shade through covers, other features and planting.
- Keeping living roots in the soil through as much of the year as possible.
- Using mulches of organic matter between your plants.
Setting Up Sustainable Water Systems for Summer
Another very important part of preparing for summer in a polytunnel is making sure that you have sustainable water systems in place. Freshwater is a precious resource and we all need to make sure that we are using it wisely and conserving it wherever and however we can.
Of course, plants inside a polytunnel will not be directly watered by rain when it falls. We will be entirely responsible for providing the water that the plants that we grow under cover need. But we should still be using rainwater to water polytunnel plants wherever possible.
We should all make sure that we catch and store rainwater from the roofs of our homes, sheds, garages etc. and also from the polytunnels themselves.
Setting up a sustainable irrigation system allows us to direct that rainwater we have collected to where it is required. Have you learnt about Watermate, the ultimate watering system for your polytunnel? Learn more now.
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Putting Water Conservation Measures in Place
Putting sustainable water systems in place to catch and store rainfall and to distribute that water through our polytunnel gardens is just part of the puzzle.
To be water wise we also need to think about the methods we can choose the strategies we can employ to conserve water, and reduce the amount of water that we need to use.
Before summer arrives, therefore, we should also prepare to put water conservation measures in place.
For example, we should water plants deeply but less frequently to encourage them to form deeper roots. Watering shallowly and less often can make plants less resilient during water shortage in the summer.
Another thing that we can do is select more drought-tolerant or low-water species when choosing our plants for summer growing.
And we can group plants in such a way that the combination reduces water use (through groundcover and shading which reduce moisture loss from the soil or growing medium).
Thinking in more ambitious terms, polytunnel growers can also consider adopting very different approaches for growing food.
For example, they can grow in water rather than in soil, and create an aquaponics system. These closed-loop systems, growing fish as well as leafy crops, can generate high yields while reducing overall water use.
Even when growing in a more traditional medium, water can be conserved by making raised beds in the right way – making wicking beds, or hugelkultur beds, for example, are both ideas that can help to reduce water use.
Preparing for Summer Holidays
As the weather warms up in the spring, you will find that the water needs of most plants will increase significantly. This can make things more difficult for gardeners who may want to plan to have some time away.
A little thought up front before summer arrives can make it easier for you to leave your garden for a short time while you take your summer holidays, without worrying about your plants while you are away.
Water is of course a key concern when preparing to go away for a week or so in summer.
Of course the easiest way to water plants in your polytunnel is to install an automated water irrigation system that can operate in your absence.
But there are also low-tech options to consider such as clay pots, glass or plastic bottles, watering globes, or wicking systems with strips of fabric between buckets and your plant pots.
Another thing to think about is weeds – as you definitely don’t want things to get out of hand while you are away. Chop and drop those weeds and get the hoeing done before you go, to make sure you don’t have a mammoth task when you get back.
You should also, of course, make sure that you have harvested all that you can before you go away, or you might miss out and it may be too late by the time you return.
Being organised about things like this can help make sure that summer in a polytunnel goes smoothly and that you get as much as possible from your polytunnel garden.
When should I start planting summer crops in my polytunnel?
The timing for planting summer crops depends on your location and the specific crops you intend to grow. Generally, you can start planting after the risk of frost has passed and the soil has warmed up. Consult local planting calendars or gardening resources for specific recommendations.
What are some recommended summer crops for polytunnel cultivation?
Tomatoes, peppers, cucumbers, aubergines, basil, beans, courgettes, melons, and various types of salad greens are popular summer crops for polytunnels. Choose crops that thrive in warm and sunny conditions.
How can I ensure proper watering in my polytunnel during the summer?
Monitor soil moisture regularly and water when necessary to keep the soil evenly moist. Avoid overwatering, which can lead to waterlogging and root rot. Consider installing an irrigation system or using drip irrigation to provide consistent and targeted watering.
Are there any specific pest control measures I should take in the summer?
Regularly inspect your plants for pests such as aphids, whiteflies, and mites. Implement preventive measures such as using sticky traps, introducing beneficial insects like ladybugs, and practicing good hygiene to minimize pest infestations. Organic pest control methods like neem oil or insecticidal soaps can be used if necessary.
How can I maximise space utilization for preparing for summer in a polytunnel?
Utilise vertical space by training climbing plants, such as tomatoes or cucumbers, on trellises or strings.
Use containers or raised beds to make efficient use of the available area.
Consider succession planting, where you sow or transplant new crops as soon as the previous ones are harvested.
Should I provide shade in my polytunnel during hot summer days?
In regions with intense sunlight and high temperatures, providing shade can be beneficial. Install shade cloth or use temporary shading methods like applying a layer of horticultural fleece or using shade netting to protect sensitive crops from excessive heat and sunburn.
How can I maintain proper ventilation for preparing for summer in a polytunnel?
Open doors, windows, or vents to promote air circulation. Install automatic vent openers or use fans to improve airflow. Consider installing roll-up or retractable side vents for additional ventilation options.
Treehugger (2023). How I Prepare for Summer in My Garden. Treehugger. [Online]. Available at: https://www.treehugger.com/how-i-prepare-for-summer-in-my-garden-7510430 [accessed 22/06/23]
Harvst (2023). Polytunnel Watering System. Harvst. [Online]. Available at: https://www.harvst.co.uk/polytunnel-watering-system/ [accessed 22/06/23]
Elizabeth Waddington is a writer and green living consultant living in Scotland. Permaculture and sustainability are at the heart of everything she does, from designing gardens and farms around the world, to inspiring and facilitating positive change for small companies and individuals.
She also works on her own property, where she grows fruit and vegetables, keeps chickens and is working on the eco-renovation of an old stone barn.
To get in touch, visit https://ewspconsultancy.com.