If you have particularly acid soil, you may find it a challenge to grow food directly in the soil in your polytunnel. If you have a pH around 5, you have very acidic soil, and if it is between 5 and 7, it is on the acidic side. If you discover that your soil is within this range, you could consider trying to make the soil more neutral by adding plenty of organic matter, or growing in raised beds or containers. However, you could also embrace the natural conditions where you live and growing some acid loving plants.
While many vegetables will not grow very well in extremely acidic soil conditions, there are a number of berries that will grow very well in acid soils and which will be the perfect foundation for an edible polytunnel garden in acid conditions. Creating a fruit garden in a polytunnel or fruit cage could be the perfect solution for your space.
Acid loving berry plants that will like/ tolerate an acid soil include:
Bilberries (also called blaeberries in Scotland) are found in the wild in many locations across the UK. But you could also consider cultivating some of these berries in a polytunnel or fruit cage in acid soil. Bilberries can be very fussy about the pH, so keep that to a constant of pH 5.5 for best results.
Blueberries are a similar berry, often confused with bilberries. But these are not native to the UK but to the US and other locations around the world. Blueberries also prefer an soil with a pH of 5.5.
Lingonberries are native to the boreal forests and more northerly regions, and yet can be successfully grown in the UK. Optimal pH for lingonberries is around 5. They prefer a well-draining soil that is rich in organic matter.
Cranberries are another excellent choice for very acidic soils, and are one of the well-known acid loving plants. Optimal conditions require a soil pH of between 5 and 5.5. It is important to note, however, that that also require high humidity and cooler positions, and a soil that retains water very well and is boggy.
Blackberries prefer a neutral to slightly acid soil, but can thrive in soils with a pH as low as 5.5. While blackberries can easily get out of control in a garden and create bramble thickets, growing some (of a thornless variety) in an orderly and trained way in a polytunnel or fruit cage could be a good idea, as this will keep the fruits safe from birds and other pests.
Raspberries can also cope with a soil down to a pH of around 5.5. These delicious fruits can also make a good addition to a polytunnel garden. Growing some under cover in a polytunnel and some outside with extend the season, and as with all the above, will also mean that fewer fruits are eaten by birds and other wildlife in your garden.
In addition to growing the above fruits, you could also consider growing:
Potatoes prefer a somewhat acidic soil, between a pH of 5 and 6, but can cope with a pH down to 4.5. These are one of the most acid loving vegetables to grow if your soil is ericaceous. Try to choose varieties that are best suited to the particular soil type in your area.
Though growing sweet potatoes is more of a challenge due to the short growing season here, these are also fairly tolerant of acid soil,and you could consider growing these in a polytunnel in the UK.
If you would like to grow herbs, parsley is one of the most acid-loving plants to consider. Parsley can grow in soils with a pH of between 5 and 7, and so could be a good choice if other herbs are out of the question and you are at the lower end of that range.
For a more exotic crop, those with acid soil could also consider growing peanuts in a polytunnel. While it can be a challenge, growing peanuts in the UK is not necessarily out of the question, and could be an intriguing option for those looking for more unusual acid-loving plants to try. Peanuts can cope with a soil pH down to 5.
These are a few acid loving or acid tolerant edible plants that you could consider growing in your polytunnel if you have acidic soil where you live.
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.