If you’re planning to plant flowers, fruit and vegetables in your garden this spring, knowing the basics about soil types holds the key to turning your gardening ambitions into reality. Follow our essential guide to getting to grips with what lies beneath your feet…
We’ve all bought a gorgeous plant on the spur of the moment, only to see it wither and die within months of planting in the garden. When plants come a-cropper, gardeners stand perplexed: Was it overwatered? Should it have been fed? Perhaps it caught a disease? In many cases, the reason can be found underground.
The saying “the answer lies in the soil” may be the oldest cliché in gardening, but it still rings true today. Keen gardeners may also be familiar with a phrase coined by the late, great plantswoman and author Beth Chatto: “Right plant, right place”. It’s a short and simple piece of advice – if the conditions in your garden are right – and that starts with the soil – then a plant is likely to make your garden it’s forever home.
With the spring gardening season underway, it’s a great time to test your soil and work out what you can and can’t grow, before planting-out time begins after the last frosts in late May (or early June, if you live in Scotland or the far north). Insider knowledge of your soil will also help you to deal with drought and waterlogging and dictate how you can improve your soil quality to grow even better flowers, fruit and veg.
Test your soil pH
The number one priority is to know your soil pH – whether the soil is alkaline, neutral or acidic. pH test kits can be bought online or at garden centres for less than a tenner. Take a soil sample from your garden, add the supplied liquids as instructed and compare the colour of the final result to the chart supplied, to determine the pH. Your soil is acidic if the test confirms a pH of 4 to 6.6, while pH7 indicates neutral soil. A reading of pH7.6 to 10 lets you know that your soil is alkaline.
That’s all well and good if you work in a laboratory, but what does it mean for home gardeners? Strongly acidic soil is perfect for heathers, magnolias, rhododendrons, blueberries, azaleas and camellias, while moderately acidic soil is just the ticket for roses, tomatoes, strawberries and popular fruit such as apples and pears.
If the test shows that your soil is alkaline, there are a host of popular garden plants that’ll love to make your garden their home, such as wallflowers, lilac, honeysuckle, lavender and delphiniums, as well as popular vegetables such as Brussels sprouts and cabbage. Alkaline soil can reduce the occurrence of clubroot, a disease of brassicas, which is a bonus for kitchen gardeners.
Of course, that’s just a snapshot of the vast range of plants that can be grown, but going to the garden centre armed with the knowledge of your soil pH helps you to choose the perfect plants for your plot. What if your soil is neutral? Most flowers, veg and trees will be at home, although you’ll have to lower the pH of the soil if you want to grow acid-loving plants – applying sulphur is one of the most common ways of acidifying soils, while digging-in old pine needles and leafmould can help, too.
Know your soil type
Determining your soil pH is the first step, but dig deeper (excuse the pun) and you’ll find out even more about the pros and cons of your soil. If it is soggy and sticky, and you can roll it into a sausage in your hand, it’s clay soil. Lots of gardeners fear clay because it can quickly become waterlogged in winter, takes longer to warm up in spring and can bake hard as a rock in summer. On the plus side, clay soils are often fertile and can be rich in minerals.
Sandy soil is the opposite to clay. It’s free-draining, unlikely to flood and warms up quickly in spring. On the downside, nutrients are easily washed from sandy soil, so adding lots of well-rotted organic matter, combined with regular feeding during the growing season, is essential to keep plants nourished.
Chalky soil often tends to be alkaline, with lots of stones which helps with drainage, while loamy soil is often regarded as a gardener’s dream; neither prone to waterlogging or too free-draining, while containing good levels of nutrients. Peaty soils are moisture-retentive and easily dug and, while too acidic for many plants, are ideal for azaleas, rhododendrons and camellias. Silty soil can be rolled into a ball but doesn’t keep its shape like clay soil – and it’s better at holding on to nutrients than sandy soil while retaining moisture, too.
What compost is best?
If your soil conditions or pH aren’t right for cultivating the type of plants that you’re keen to grow, then almost anything can set up home in a container. Choosing the right compost to fill pots is an area where gardeners can make mistakes, so we’re here to guide you through the minefield of products on offer.
If you plan to grow plants from seed, it’s always worth investing in a quality seed and cuttings compost. Such composts are usually a very fine grade (no lumps) with excellent drainage – perfect for coaxing seeds into life and helping cuttings to take root.
Multi-purpose composts are fine for filling containers that’ll be home to plants for no longer than six months, such as summer bedding. Tub and basket compost, which is similar to multi-purpose but contains wetting agents to retain more moisture, can help to prevent plants from drying out in hot weather.
John Innes composts, which are made to precise, traditional formulas, can cause confusion – which do you choose, John Innes number one, two or three? It’s easily explained. John Innes No 1 is for establishing seedlings and very young plants while John Innes No2 is suited to potting-on young flowers and vegetables. If you’re looking to grow shrubs, trees and climbers in containers, where they are likely to remain for years, choose John Innes No.3. It contains the highest level of nutrients of the John Innes trio, and is also ideal for fast-growing, hungry crops such as tomatoes.
And finally, if you’re a fan of acid-loving plants such as camellias, azaleas and rhododendrons, but have unsuitable alkaline soil, grow them in big pots filled with a John Innes ericaceous compost, which is perfectly blended for shrubs that love to get their roots down into acidic conditions.
What type of soil do you have in your garden? And what likes to grow in it? Let us know in the comments.
I’ve added this in as clay loam is a suggested term, however, I’m not too sure whether clay loam soils and clay soils are the same things?
Marc Rosenberg bio
Marc Rosenberg is a freelance garden writer and editor. A former journalist with Amateur Gardening and Horticulture Week magazines, he holds seven Garden Media Guild Awards. Marc has written for publications including The Garden magazine, BBC Gardeners’ World and RHS online.