One of the most important things in successful, sustainable gardening is learning how to choose the right plants for the right places. While gardeners can amend and improve the soil in their gardens over time, selecting plants well suited to the conditions in the growing area is the best recipe for success. Polytunnel growers who take the soil conditions where they live into account and select plants carefully will be far more likely to meet with success. They will be able to work with nature rather than endlessly fighting against it. Acidic soil is one of the factors which can determine which plants will be best to grow where you live.
Small polytunnels and large polytunnels can all help you control the environment and grow your own food efficiently and effectively. But if you do not understand your soil, and pay attention to its pH, you are far more likely to encounter problems along the way. In this article, we will look at some of the top plants that thrive in acidic soil conditions, to help you plan the best possible, sustainable planting scheme for your garden.
Determining the pH of Garden Soil
Before we begin to look at which plants you might like to choose, we need to establish an idea of the pH in your particular growing areas.
If your soil has a pH of between 4.5 and 7, it is acidic. A pH of 7 is neutral. A somewhat acidic soil is one just below this figure, while if you have a pH around 5, you have very acidic soil. The further soil is from neutral, generally speaking, the more challenging it will be for the gardener.
You can determine the pH level in your garden soil with the aid of a pH tester kit. However, simply looking around and observing the plants already growing in the area can give you a good clue as to the pH levels in the soil in a given area. You can also find out more information on the pH of the topsoil in your area by looking at information from the UK Soil Observatory. http://www.ukso.org/static-maps/countryside-survey-topsoil.html
Do you Need to Amend Acidic Soil?
Whether or not you need to amend your acidic soil will depend on how extreme the acidity is in your soil. If your pH test shows soil that is pH 3.0 to 5.0, this is very acidic soil. Unfortunately, this means that most plant nutrients will become more soluble and be easily washed away. Most phosphates will be locked up and become unavailable to plants. Below a pH of 4.7, bacteria cannot rot organic matter and fewer nutrients become available to plants. This is problematic for gardeners and if your soil is this acidic, you will either have to grow in containers with a more balanced growing medium or add lime to raise the soil pH above 5.0.
An acid soil above 5.0 and below 7.0 is not as problematic. Indeed, a slightly acidic soil can be ideal for gardeners. Generally speaking, if your soil is somewhat acidic, it is best to choose plants suited to the conditions, rather than making any effort to amend the soil.
A somewhat acidic soil can be perfect for acid-loving (ericaceous) plants and can be amended with lime to grow other plants which prefer a more neutral balance. The number you are generally aiming for is pH 6.5, which is said to be the best pH for gardens and allows a wide range of plants to grow. The availability of major nutrients and the bacterial and earthworm activity are at their best at this pH.
Choosing Plants for Acidic Soil
It is important to remember that pH, while it can be an important environmental factor, is only one of a series of criteria that you should consider when choosing plants for your garden. The plants listed below are generally good for acidic soil conditions. However, it is important to also consider factors like sunlight and shade, soil moisture levels, soil type, and fertility levels – all of which will also play a role in determining which of the following plants might be right for you.
Top Ten Trees For Acidic Soil
One of the best places to begin when planning planting for your acidic soil garden is with the upper layer, or tree canopy. Planting trees can help you provide a structure for your garden, and give you a good place to begin when improving the sustainability of your garden and the quality of its soil. Trees help to stabilise soil and provide a bountiful source of biomass for your garden. While many trees will not really thrive in acid conditions, these trees below will do well with an acidic pH.
- Pin oak
- Japanese Acers
- Rowan (Mountain Ash)
- Douglas Fir
If you are planning to include edible top fruits in your garden, apple trees are one of the best options. Apple trees can be found which are suitable for many different situations and these trees will thrive at a moderately acidic pH of around 5-6.5.
Top Ten Shrubs for Acidic Soil
It is, arguably, in the shrub layer that ericaceous gardens really come into their own. Acid gardens will bloom into life with a range of stunning acid-loving flowering shrubs with big, bold and beautiful displays. Shrubs can find a place in all acidic condition gardens – large or small. Here are some shrubs that can do well in an acid soil:
- Pieris japonica
- Heather (Calluna vulgaris)
Edible plants For Acidic Soils
Acidic soil gardens can be truly beautiful, with a range of interesting foliage and beautiful blooms. But gardeners should not only think about the visual appearance of their gardens but also about how they can use their outside space to provide food for themselves and their families. A polytunnel can make it easier to grow your own food year round, as can fruit cages to protect top fruits and soft fruits elsewhere in your garden.
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 garden in acid conditions. Acid loving berry plants, and edible plants that will tolerate an acid soil include:
- Bilberries/ Blaeberries
Amongst vegetable crops, potatoes are one of those that is most tolerant of acid soils. The potato prefers a pH of around 4.5-6.
Top Ten Flowers for Acidic Soil
Of course, in addition to growing food, most of us do also want out gardens to be beautiful. Flowers can bring life and colour into our gardens. Fortunately, there are plenty of ericaceous flowers that will work well in acidic soil conditions. Not only will introducing flowering plants enhance the visual appeal of your garden, it can also help you to attract beneficial wildlife to the space, and aid pollinators and other helpful creatures living nearby.
There are plenty of pretty flowers for acid soil gardens. Here are just some examples:
- Lilyturf (Liriope muscari)
- Japanese anemones
- Japanese iris
- Trillium erectum
- Summer Heather (Calluna vulgaris)
- Lithodora diffusa
A number of ferns can also be grown in acid soil and will add a different kind of visual interest to a garden. Ferns can be especially useful in areas of shady, damp acidic soil. Challenging areas of your garden can be an opportunity to try something a little bit different.
Of course, many more plants can also be grown in acid soils, especially when those soils have been amended with organic additives to make them more pH neutral. Embrace your acid soil to create a beautiful and abundant growing space. You can always add some raised beds to grow some vegetables and other crops that will not thrive in your natural soil.
Do you have acidic soil in your garden? What successes or challenges have you met with? Share your comments, tips or suggestions for acidic soil gardening in the comments below.
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.