Choosing the right plant for the right place involves developing a good understanding of your garden. When we understand the soil, sunlight, shade, water and other factors in our environment and what they mean for our growing efforts, we are better able to work with nature to achieve our growing goals. Choosing from a variety of domestic polytunnels can help us to control our environments. These structures can make it easier to garden, whatever the conditions. Yet soil pH can often be more of a challenge to amend or control. Alkaline soil can be a challenge for gardeners. But if you choose the right plants, it can also afford plenty of exciting opportunities.
In this article, we will take a look at some of the top plants that thrive in alkaline soil. But before we begin to look at some planting suggestions, and explore the solutions for alkaline soil in a little more depth, let’s take a brief look at how to determine whether the soil is alkaline where you live:
Determining the pH of Garden Soil
If your pH is between 7.1 and 8.0 then you are dealing with an alkaline soil. You can buy pH tester kits which will allow you to test the soil in your polytunnel or other growing areas. If you are not sure whether you have alkaline soil, but do not wish to purchase a pH tester kit, you can also take some of your soil and place it in vinegar. If it froths up, it is high in lime and alkaline in nature. If in doubt, you can also find more information about the soil where you live on the UK Soil Observatory website: http://www.ukso.org/static-maps/countryside-survey-topsoil.html.
Do you Need to Amend Alkaline Soil?
Alkaline soil can cause some problems. Phosphorus, iron and manganese become less available when the pH is alkaline, especially if it is more extremely so. However, some plants, including some vegetables, may thrive in slightly alkaline conditions. For example, club root disease in cabbage family plants is reduced. There are also some other conditions which can be reduced or eliminated in more alkaline soil.
You can also consider growing certain plants in containers or raised beds if the conditions are not suitable for growing plants you wish to grow directly in the ground. Adding neutral mulches and organic material can generally help to improve the structure of alkaline soils and improve nutrient and water retention.
Sometimes, extremely alkaline soil can be amended with the addition of large amounts of acidifying organic material. For example, this can be achieved with a heavy mulch of pine needles. However, generally speaking, it is best to simply choose plants that are well-suited to the conditions. Mildly alkaline soil can actually be an advantage, and so amending this soil is not usually the best option. Rather, think about the other challenges posed by your soil type (such as poor nutrient retention or water retention) and think about how these, rather than pH, can be overcome.
Choosing Plants for Alkaline Soil
Alkaline soil is often chalky, and so choosing plants for alkaline soil often involves choosing plants suited to a chalky soil environment. Challenges can often include an extremely free-draining soil structure and often relatively low fertility. Fortunately, however, there are still plenty of plants that will thrive in a chalky, alkaline soil environment.
When choosing plants for alkaline soil, it is important to take not only pH but also other environmental factors into account. You should consider soil type, soil moisture and fertility, and other environmental factors such as sun and wind into account. That said, the plants listed below should give you a good place to start when choosing the right plants for the right places in your alkaline soil garden:
Top Ten Trees for Alkaline Soil
If you are planning a new garden or growing area from scratch, the tallest, tree layer is often a good place to start. Placing trees can help you to provide shade which will help retain water, and can provide a valuable source of biomass for your garden. What is more, trees will improve soil stability, can be a windbreak, and can also provide habitat and food for a wide range of local, beneficial wildlife. Some trees that might be suitable for your alkaline soil include:
- Field maple
- Holm oak
- Strawberry tree
- Sorbus alnifolia
- Montezuma pine
- Cotoneaster frigida
Top Ten Shrubs for Alkaline Soil Top
Shrubs are suitable for all gardens, large and small. They can also help to provide shade and biomass, and also provide cover and habitat for a range of beneficial garden creatures. There are plenty of shrubs that are perfectly well suited to alkaline soils and which will thrive in such conditions. These include, but are not limited to:
- Santolina chamaecyparissus
- Viburnum opulus
- Deuzia ‘Pride of Rochester’
Top Ten Edible Plants for Alkaline Conditions
Those with mildly alkaline pH will often find it easy to grow a wide range of vegetables. Cruciferous vegetables like cabbage and broccoli in particular can thrive in a slightly alkaline environment. Legumes can also often thrive in an alkaline soil environment. Those with free-draining soil will also often find it easy to grow a wide range of Mediterranean herbs. Top edible plants for these particular soil pH conditions include:
- Broccoli/ Brussels sprouts
- Kale/ collard greens
- Pole beans
Top Ten Flowers for Alkaline Soil
Of course, creating a successful and sustainable garden is not only about edible plants for humans, but also about providing a food source for pollinators and attracting beneficial wildlife throughout the year. Some good flowering plants for alkaline conditions include:
- Lily of the Valley
- Viper’s Bugloss
- Trifolium (clovers)
- Wild marjoram
- California Poppies
The examples given above are just a small sample of the many plants that can be successfully grown in alkaline conditions. The key to success is to embrace the natural conditions in your garden and to choose plants that will thrive there. Choosing the right plants for the right places will help make sure that your garden can survive an thrive for years to come. By working with nature rather than fighting against it, you can make the most of your garden.
Do you garden in an alkaline soil environment? Which plants have you found to work well where you live? What challenges have you faced in your garden, and what successes have you had? Do you have some tips or suggestions to share? Please feel free to share these 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.