The Garden in February 2025

I would like to say that February is one of my favourite months in the garden- but, unfortunately, I can’t! Some gardeners would even point out the only good thing about February is that it gets us closer to March but the truth is that, although not a stand out month, February does have some good features if we are prepared to look for them.

For example, in my 2021 blog I was looking at some great ‘February plants’ including the shrubs Hamamelis, Sarcococca and Chaenomeles and the early flowering bulbs and perennials such as Galanthus, Cyclamen coum, Narcissi, Helleborus, Pulmonaria and Primroses. I also included some February jobs such as pruning deciduous hedges and some types of clematis, adding organic matter to the soil surface, feeding the birds and possibly even some seed sowing inside. In 2022 the blog came from the gardens at Aberglasney and in 2023 I was looking at some ‘bee friendly’ plants for this early in the year, winter pruning and preparing nest boxes for the season ahead. Last year I highlighted some other good late winter plants such as Iris unguicularis and Pieris japonica as well as looking at how we can make our gardens more bird friendly and taking a look at peat free composts.

A few very welcome flowers in a brief sunny spell in late January!

For my first topic this month I am going to say a little more about Mahonias which I mentioned briefly last month by referring to an article in the December 2024 issue of the RHS magazine ‘The Garden’. The writer, Ross Bayton, lives in the north west of the USA in Washington state near Seattle and has a real passion for Mahonias which grow well in his cool, damp climate- sounds familiar? In the article he recommends some of his favourites and suggests different ways they can be used in garden settings. Mahonias are members of the Barberry family which also contains the Berberis genus and when you think about the Mahonia’s spikey leaves, yellow flowers and purple-black berries this is not at all surprising. They are native to North America and Asia with their greatest diversity in Mexico and China. Europe has no native species (remember the ice ages and west-east mountains of Europe as mentioned last month?) although Mahonia aquifolium (the Oregon Grape) has escaped from gardens into the wild via birds which relish the berries. Ross writes that Mahonias are sophisticated and smart in looks and that they have much to offer the gardener. They make upright shrubs of various sizes and the most commonly available species and cultivars thrive with little care in a wide range of garden settings. A bit of shade is preferable in most cases and they really prosper in an edge of woodland position. Apart from a light application of a slow-release fertiliser in spring they are not demanding in terms of soil fertility. Smaller Mahonias require no pruning and larger shrubs such as Mahonia x media cultivars respond well to hard pruning from time to time in late spring or early summer to produce a more branched plant and to control the overall size. Insect pests are rarely a problem and the combination of leathery, prickly leaves containing chemical defences deters most animals. Some plants also have flushed red leaves in winter while others produce dazzling red leaf growth in spring and all Mahonias are included on the RHS list ‘Plants for Pollinators’. In fact, you may have noticed in January that Mahonias were mentioned during one of the episodes of the BBC’s ‘Winter Watch’. Evidently, they are a very important food source for queen buff tailed bumblebees which emerge at this time of year in search of a winter snack!

Amongst Ross’ favourites are three cultivars of Mahonia x media. M x media ‘Lionel Fortescue’ is a large plant available in most garden centres with long flower racemes (spikes) up to 6” (15cm). ‘Winter Sun’ is more compact, very floriferous and is strongly scented and ‘Marvel’ is an easy to grow plant with dense clusters of yellow blooms and is unique in its neat, less spiny foliage. Another Mahonia with strongly scented, pale yellow flowers is the species Mahonia japonica. Ross also recommends a fairly recently introduced Mahonia, M. eurybracteata subsp. ganpinensis ‘Soft Caress’- shall we just call it M. ‘Soft Caress’? This has almost spineless, slender leaves, a petite growing habit and yellow flowers in delicate fingers followed by black berries. As for their use in the garden they are used mainly as large statement, evergreen shrubs in mixed beds and borders particularly in shadier spots. Smaller plants such as ‘Soft Caress’ are good choices for growing in containers while suckering species such as cultivars of Mahonia repens make ideal ground cover plants again in shaded positions.

A welcome sight in the depths of winter

My second topic for this month is one which is very close to my heart as a gardener and former teacher of physical geography and that is soil. Although it only covers about 10% of the Earth’s surface, soil supports a huge array of biodiversity both within it and above it. In fact, some estimates suggest that around half of all species on Earth live in soil and that just one teaspoon of soil can contain up to an incredible 40 billion organisms! So, it is definitely not just dirt or mud, it is a fascinating and complex ecosystem in its own right. Above the ground a vast food web which includes us depends on soil, from birds feeding on soil invertebrates to the plants, trees and hedgerows rooted in it, which in turn support a myriad of other species. As for us, about 95% of the food we eat comes the soil and without it we simply couldn’t exist.

So, what actually is soil and what is it made of? Essentially all soils are made up of four components but in a wide variety of mixes or recipes which produce many quite different soil types across the world. These are the products of their environments, their climates, their vegetation cover and especially the rocks below them. For the vast majority of soils their main ingredient is inorganic mineral matter which is produced by the rock below breaking down very slowly over time by a process known as weathering to form lots of particles of various sizes and chemical make-up. The three main size groups from smallest to largest are clay, silt and sand and their relative proportions, referred to as soil texture, are determined by the type of rock from which they are formed. This mixture in turn produces different soil characteristics which we gardeners are well aware of such as good drainage (lots of sand), poor drainage (lots of clay), levels of fertility (sand low, clay high), ease of working (sand easy, clay hard) and speed of warming up (sand quick, clay slow). A soil with a ‘good’ balance of the three sizes has all the advantages without the disadvantages and is known as loam which, of course, is what most farmers and gardeners prefer to work with. The second constituent of soil might be low in terms of percentage weight or volume (usually less than 5%) but it is an absolutely vital part. This is organic matter in all its forms and is the reason why soils are so rich in biodiversity. It is made up of vast numbers of very small microorganisms both alive and dead as well as live, dead and decaying plants and animals. When fully broken down by microbiological activity such organic matter produces a truly magical substance called humus which is black and sticky and full of useful chemicals for plant growth. It also helps to bind the soil particles together and cleverly holds on to water and plant nutrients until they can be absorbed by plants through their roots. The other two components of soil are more variable in their proportions than the first two, one increasing as the other decreases. These are air and water which are held in the pore spaces between the soil particles and are both vital for healthy plant growth. Following heavy rain most, if not all, pores are filled with water which slowly drains away under gravity over the next days and weeks, firstly from the larger spaces, to be replaced by air unless of course the water content is replenished by further rain.

Within the soil these components tend to form in layers known as horizons which in their simplest forms are the topsoil, subsoil and weathered parent material beneath. Most of the organic material is found in the topsoil so this is the most fertile layer and tends to be darker than the rest because of its relatively high organic content. It is this layer that gardeners really need to think about and to work on in order to provide the best possible conditions for plant growth. There is little to be done about soil texture other than adding sand or grit to clay soils to improve their drainage but a great deal can be done to increase the organic content and to gain all the benefits which this can bring. This is the reason for adding organic matter such as well rotted manure, leaf mould, garden compost, spent mushroom compost or soil conditioner from green waste recycling either by digging in or simply applying to the soil surface. Our soils also tend to become compacted over time which closes up the pore spaces leading to poor drainage and lack of air. This is why gardeners spike and aerate lawns and dig and fork over the ground between plants. They can get help with such work by encouraging natures’ digger- the earthworm, simply by providing lots of organic matter which they will quickly incorporate into the soil and in doing so create more spaces within the soil. Gardeners can also increase soil fertility by adding materials which contain the three major plant nutrients- nitrogen phosphorus and potassium, (often referred to as N,P,K) plus important trace elements such as magnesium, iron and sulphur. These can take the form of chemical fertilisers such as Growmore or organic fertilisers such as blood, fish and bone, bonemeal, seaweed extract or manures in both natural or pelleted forms. I much prefer the organic materials which tend to be released more slowly into the soil and are less likely to be leached away into the ground water and streams. So, the basic message, as always, is look after your soil and its life and it will look after your plants and continue to support one of the world’s most important ecosystems.

Well, that is all for this month but I will be back in March with another blog and the first Saturday morning talk of 2025 on March 1st- a perfect way to start St David’s Day! As always, I will take a look at what the Old Railway Line has to offer in terms of spring plants, will be admiring the flowers brought in by my ‘regulars’, attempting to answer any questions from the floor and perhaps even coming up with a few surprises! There will be more details on the ORL website nearer the time under ‘events’.

By then, of course, we will all be full of the joys of spring and dull, damp and cold February will be all but a distant memory! Until then take care of yourselves and enjoy your late winter garden as much as you can.

Keith.