Why You Should Ditch Peat

Jeremy Bartlett's LET IT GROW blog Posted on by
Large Heath butterfly

The Large Heath butterfly – a species that has seriously declined following destruction of peat bogs. (The plant in the background is Bilberry, Vaccinium myrtillus.)

This morning we walked to our local garden centre. It was good to stretch our legs, but the experience was rather disappointing. Like many such places, it has become more gift shop and cafe than a place to buy plants. The only Hollyhocks on sale were double-flowered and therefore useless to pollinators and the trays of mixed blowsy-flowered Primulas made me feel a little bilious. We came away empty handed (note 1).

Saddest of all were the huge piles of bags of compost by the entrance, most of which contained peat.

In the United Kingdom, the industrial scale extraction of peat has destroyed or damaged more than 95% of lowland bogs. In Ireland, the Irish Peatland Conservation Council (IPCC) estimate that 90% of its raised bogs have been lost (note 2). As the IPCC say: “Peat may be dirt cheap, but it costs the earth.”

Peat is composed of waterlogged, partially-decomposed plant material (including sphagnum moss and other acid-loving plants), which builds up in wetland habitats such as fens, bogs and moorland. The process is slow: about 1 millimetre of peat forms in a year, and deposits in the British Isles have gradually built up over 10,000 years. In contrast, average annual extraction from a peat bog removes 20cm (8 inches) of peat in a year, which represents 200 years of peat formation (note 3). It’s actually worse than that because bogs are drained before extraction takes place, to allow machinery to work on the site. This kills off large tracts of peat and its unique plant and animal community. Industrial scale peat extraction is no more sustainable than clear-felling rainforest to create palm oil plantations.

Peat bogs are wonderful places, full of interesting plants, including beauties such as Bog Asphodel and Grass of Parnassus, which I have previously written about. Insect life abounds there too, such as the Black Darter dragonfly and, pictured above, the Large Heath butterfly. More recently, we have realised that peat bogs are great carbon sinks, capturing carbon dioxide from the atmosphere. It has been estimated 5% of the carbon currently locked up in the UK’s peatlands is equivalent to the UK’s annual greenhouse gas emissions (note 4). Peat bogs also store vast amounts of water and slow its release into rivers, preventing catastrophic flooding (note 5).

Some three billion litres of peat are used every year in our gardens. We have known that harvesting peat is damaging and unsustainable for many years, but the majority of commercial composts still contain a large proportion of peat. Unless a bag of multi-purpose compost says it is peat free, it will contain peat. Some bags say that the peat doesn’t come from a SSSI (Site of Scientific Interest), but this is either because the extraction site is so degraded that it has no designation or if it comes from outside the United Kingdom, where the term SSSI isn’t used (note 6).

In December 2010 the British Government announced a plan to phase out the horticultural use of peat by gardeners by 2020. But as I write, peat extraction for gardening in the UK is still rising.

The following quote from Monty Don, which dates from March 2002, is still sadly true:

“Go to any garden centre and try and buy a non-peat based compost. It is certainly easier now than it was even five years ago, when you had more chance of scoring a bag of heroin over the counter at the local supermarket, but you still have to fight past the pallets of peat and peat-based composts to get to it.”

Alternatives to Peat

I stopped using peat in the 1980s.

For containers of shrubs and hardy perennials I use my home-made compost, which starts off as kitchen and garden waste. However, my own compost doesn’t rot at a high enough temperature to kill all weed seeds, so I use a commercial compost for the top inch or so of the pot, to stop light from triggering  germination of unwanted seedlings. (Peter Hill also suggests this in his February 2010 Guardian  article “Tips for a Peat Free Garden“.)

For raising seedlings and small plants, whether vegetables or wild flowers, I buy bags of peat-free compost.

The quality of composts can be variable, and I have learnt that some ones are better than others. Price can be an indicator, as you generally get what you pay for. I have had the occasional failure: about twenty years ago one (not cheap) brand of peat-free compost, whose formula has now changed, only gave me a crop of Common Inkcap fungi, rather than the potatoes I had hoped for.

If you’re switching to a peat-free compost, bear in mind that the compost may behave differently to a peat-based one. This is not necessarily a bad thing, but it’s best to check that plants really need watering. The surface of a coir or wood-chip based compost can dry out on the surface while the depths remain moist. Don’t rely on visual clues – poke a finger into the compost to check.

There is a lot of useful advice on peat-free composts online. One of the best articles I’ve found comes from the Telegraph just a couple days ago. There are also recommendations on the RHS and  Earth-Friendly Gardener websites. It includes some recommended brands. I’ve had success  New Horizon compost (a blend of coir, wood fibre and bark) and Fertile Fibre. The former is available in many garden centres, as well as DIY stores such as Homebase and Wickes. Buying online with home delivery makes sense if you don’t have a car, or a garden centre near where you live.

Peat is often used to lower soil pH, making it more suitable for growing lime-hating plants such as Blueberries and Rhododendrons. But peat-free ericaceous composts are available, including Ericaceous Wool Compost and Vital Earth Ericaceous Compost. I’ve had success growing Blueberries in a tub in a wool-based compost. On a larger scale, it is probably better to stop fighting nature and grow plants suited to your garden soil.

Notes

Note 1:  To be fair, they did have a smaller number of nice plants too, including some Cowslips and a couple of varieties of Lungwort.

Note 2: This loss has resulted from a combination of commercial peat extraction, turf cutting and forestry. See http://www.ipcc.ie/help-ipcc/be-a-peat-free-gardener/.

Note 3: Plantlife gives a higher figure: “Commercial extraction can remove over 500 years worth of ‘growth’ in a single year“.

Note 4: IUCN UK Peatland Programme (2011), Commission of Inquiry on Peatlands: Summary of Findings, October 2011. Quoted by Plantlife: https://www.plantlife.org.uk/uk/our-work/campaigning-change/why-we-need-to-keep-peat-in-the-ground-and-out-of-our-gardens.

Note 5: One inspiring story, reported in the Independent newspaper in January 2016, comes from Pickering in Yorkshire, which was flooded four times between 1999 and 2007. Rather than building an ugly and expensive flood wall in the town, local people, local councils, the Environment Agency, the Forestry Commission and DEFRA (the Department of the Environment, Food and Rural Affairs) worked together to slow water flow from surrounding moorland. The scheme worked well, the peat soaked up excess rainfall and the scheme cost only a tenth of building a flood wall.

Note 6: Even in Northern Ireland and the Isle of Man, the alternative term Area of Special Scientific Interest (ASSI) is used. Currently 32% of our peat comes from the UK, 60% from Ireland and 8% from Europe. (Plantlife: https://www.plantlife.org.uk/uk/our-work/campaigning-change/why-we-need-to-keep-peat-in-the-ground-and-out-of-our-gardens.)

Lungwort, Pulmonaria officinalis

Jeremy Bartlett's LET IT GROW blog Posted on by
Lungwort, Pulmonaria officinalis

Lungwort, Pulmonaria officinalis. Growing at the base of an east-facing wall in a garden in Kelling, North Norfolk, early April 2018.

Spring has arrived all of a sudden, with record-breaking February temperatures in parts of Britain. While it has been lovely out in the sunshine, the unseasonal weather is distinctly unsettling, with our knowledge that the Earth is expected to experience more record-breaking temperatures this year (note 1).

One result of the extra warmth has been the early appearance of hibernating bumblebees, butterflies (Peacock, Small Tortoiseshell, Comma and Brimstone) and the emergence of some solitary bees. One of these has been Anthophora plumipes, the Hairy-footed Flower Bee, which feeds on spring flowers such as Primroses, ‘Bowles’ Mauve’ Wallflowers and Lungwort.

Lungwort, Pulmonaria officinalis, normally starts to flower in March and continues through to May.  It’s a slow-growing perennial plant and has characteristic white spots on its leaves. Like Oysterplant, it is a member of the family Boraginaceae. Unlike Oysterplant, you won’t find it on a beach but in a garden or naturalised in woods, scrub or on waste ground. Lungwort has purple flowers, which start off pink, like several other members of its family.

In the British Isles the plant is an introduction, but it occurs widely in the wild in continental Europe. The plant prefers fairly open shade, a reasonably moist but not waterlogged soil and not too much summer heat. It is hardy to UK hardiness zone H4 (-10ºC to -5ºC). Lungwort flowers lack scent, but bees still are able to find them, possibly (with the ability to see ultraviolet light) as “incandescent beacons, shining like lamps in the semi-shade” (note 2).

The article “Biological Flora of the British Isles: Pulmonaria officinalis” is well worth a read (note 3). It snappily describes the plant as a “distylous, perennial rosette hemicryptophyte“. Distylous means that the flowers come with long and short styles and stamens, rather like pin- and thrum-eyed Primroses. A hemicryptophyte is a plant whose perennating buds are at ground level, the aerial shoots dying down at the onset of unfavourable conditions (such as in the heat of summer).

Like the name Lungwort the scientific name, Pulmonaria, refers to the lungs (Latin Pulmoa) . This is because the plant’s spotty leaves were thought to resemble diseased, ulcerated lungs. The Doctrine of Signatures, used in folk medicine, drew upon the belief that if a natural object looked like a part of the body it could cure diseases that arose there (note 4). Other examples include Liverworts, Spleenwort, Eyebright and Toothwort. The specific name ‘officinalis‘ refers to Lungwort’s use in herbal medicine.

Lungwort leaves have a high mucilage content and have been used externally for the treatment of burns and eczema. Internally, the plant has been used to treat sore throats, as well as chest conditions such as coughs (sometimes in conjunction with Coltsfoot). Lungwort’s phytochemistry has only been investigated very recently (note 5).

Lungwort leaves are edible raw or cooked but the plants growing in my dry garden soil need all the leaves they can grow, just to survive, so I haven’t tried them. Besides, the plant doesn’t exactly have rave reviews on the Plants For A Future website. “A fairly bland flavour… an acceptable addition to mixed salads, though their mucilaginous and slightly hairy texture make them less acceptable when eaten on their own“. Cooked, the young leaves “make a palatable cooked vegetable, though we have found the texture to be somewhat slimy.”

I am not alone in recommending Pulmonaria officinalis and other Pulmonaria species as garden flowers: Lungwort was Plant of the Week in The Guardian in March 2017 and featured in The Telegraph in 2002. The RHS also offers advice on growing the plant. Different Pulmonaria flower colours and leaf shapes are available, as are plants with unspotted leaves. My own favourite remains Pulmonaria officinalis and I have fond memories of it growing in gardens in north-east Scotland.

Two other Lungworts grow wild in the British Isles, but are not common and I haven’t seen them (but see Update – May 2019, below). Both are native, unlike Pulmonaria officinalis.

Narrow-leaved Lungwort, Pulmonaria longifolia, grows in light shade in Hampshire, around the Solent and on the Isle of Wight, and in Dorset, near Poole Harbour. It has narrower, oval, bluish-green lightly spotted leaves and smaller, but “piercingly blue” flowers (note 2).

Unspotted or Suffolk Lungwort, Pulmonaria obscura, grows only twenty miles from home, but is confined to three privately-owned Suffolk woods, which are inaccessible by public transport and only seldom open to public visits. Its name comes from the lack of spots on its leaves, but as I haven’t seen it, I think that “Unspotted” is rather appropriate. The lovely NatureGate website has photographs of this lovely plant, which also grows in southern Finland.

Lungwort is also known by other English names, including Mary-spilt-the-Milk (note 6), Lady’s Milk-drops (from the spots on the leaves), Spotted Dog, Soldiers and Sailors, Jerusalem Sage, Bethlehem Sage and Jerusalem Cowslip. I wonder whether the “Jerusalem” and “Bethlehem” names come from the plant’s Easter flowering time, but I have so far been unable to find out.

Notes

Note 1: The article “Media reaction: The UK’s record-breaking winter heat in 2019” on the Carbon Brief website is well worth a read, and includes Met Office diagrams showing how great the maximum daily temperature anomalies have been.

Note 2: I recommend Peter Marren’s very enjoyable book “Chasing The Ghost – My Search For All the Wild Flowers of Britain” (Square Peg, London, 2018). It has some very vivid descriptions of Lungwort flowers, including Pulmonaria longifolia and P. obscura. He managed to see P. obscura in Suffolk, and found that is “not only attractive and grows in a lovely, wild location, but is also reasonably distinctive and not ‘obscure’ at all”.

Note 3: See Sofie Meeus, Rein Brys, Olivier Honnay and Hans Jacquemyn (1992) – “Biological Flora of the British Isles: Pulmonaria officinalis“.  Reprinted in the Journal of Ecology (2013), 101, 1353–1368.

Note 4: The Swiss physician Paracelsus was an important advocate of the Doctrine of Signatures and thought that “Nature marks each growth… according to its curative benefit“.

Note 5: See Krzyzanowska-Kowalczyk J, Pecio L, Moldoch J, Ludwiczuk A, Kowalczyk M. Novel (2018) –  “Phenolic Constituents of Pulmonaria officinalis L.”  Molecules. 2018;23(9):2277. Thanks to the United States National Center for Biotechnology Information for putting the article online.

Note 6: Richard Mabey (1996): “Flora Britannica“, Sinclair-Stevenson, London. Page 306.

Update – May 2019

I have now managed to see both Unspotted or Suffolk Lungwort, Pulmonaria obscura, and Narrow-leaved Lungwort, Pulmonaria longifolia. In early May I helped with a count of plants in two of the woods where Suffolk Lungwort grows, then in mid May I went to see Narrow-leaved Lungwort while staying on the Isle of Wight. Here are pictures, for comparison with our better known spotty friend:

Narrow-leaved Lungwort, Pulmonaria longifolia

Narrow-leaved Lungwort, Pulmonaria longifolia.

Unspotted or Suffolk Lungwort, Pulmonaria obscura

Unspotted or Suffolk Lungwort, Pulmonaria obscura

Oysterplant, Mertensia maritima

Jeremy Bartlett's LET IT GROW blog Posted on by
Oysterplant, Mertensia maritima

Oysterplant (Mertensia maritima) and Sea Sandwort (Honckenya peploides) growing on Orkney.

A few weeks ago a lady from Northern Ireland contacted me and told me about some of the plants she’d seen for the first time in her local area in 2018, one of which was Oysterplant. It’s a favourite of mine, but a plant I rarely see.

Oysterplant, Mertensia maritima, is a beautiful perennial that grows on sand, gravel and shingle beaches. It grows close to the ground with a spreading habit, with blue-grey leaves and, from June to August, clusters of reddish flowers that turn blue as they age, in a similar way to Forget-me-nots and several other members of its family, the Boraginaceae. (I have previously written about some of these: Green Alkanet, Viper’s Bugloss, Navelwort and Abraham-Isaac-Jacob.) There are some lovely pictures of it on the West Highland Flora and UK Wild Flowers websites.

Mertensia maritima has a large taproot that reaches down through sand or shingle to find water, as well as anchoring the plant in its exposed habitat. In winter the leaves die back to ground level. The plant spreads by seed (nutlets) and these can be transported by wind and sea and have been known to travel at least 450 km (280 miles). Germination is unaffected by up to 18 days of immersion in sea water and the seeds are capable of staying dormant for several years, until the right conditions trigger germination (note 1). Flowers appear to be mostly self-pollinated in Northern Ireland but in some places (such as on Svalbard) they are visited by insects.

Sometimes the plant occurs as a casual for just a few years before being washed away by storms but colonies can persist for hundreds of years when conditions are right. (Plants growing in pure sand are usually short-lived.)

Mertensia maritima is very much a plant of northern areas. In the British Isles it can now be found in Scotland (especially Orkney and Shetland) and Northern Ireland. In Northern Ireland it is on a list of Priority Species;  the plant also features in a 1992 article in the Irish Naturalists’ Journal. There are pre-2000 records from Northern England, North Wales and the Isle of Man, but the plant is contracting its range in the south and expanding its range further north. Further afield, the plant grows in Svalbard, Franz Joseph Land, Iceland, Greenland, North-east Asia and North America, including Canada and, in the United States, New England (note 2). Its southern limit more or less corresponds with the mean January isotherm of 4.5 °C and the mean July isotherm of 19 °C.

With its northern distribution, Mertensia maritima may well be adversely affected by climate change (note 3). The Online Atlas of the British Flora gives storms, recreational pressures, shingle removal and grazing as reasons for losses. Like the Sea Pea (Lathyrus japonicus) that I wrote about in August 2017, visitor pressure may be very significant.

Here are some examples of the threats to Oysterplant:

I’ve only seen Oysterplant twice and in both cases the location of the plants made my memories stronger.

I first saw the plant in 1997 on a a three week cycling trip in Iceland. While we were camping in Reykjavik we walked down to the harbour to look at the Sun Voyager. The sculpture was lovely and so was the Oysterplant growing on the shoreline nearby.

The second sighting was on another cycling trip, this time in 2006, on Orkney. We were camping in Kirkwall and decided to visit South Ronaldsay for the day. Cycling south to the Tomb of the Eagles at the far end of the island we crossed the Churchill Barriers (note 4).  Oysterplant was growing in a sandy area next to one of the Barriers.

The leaves of Mertensia maritima are edible, both raw and cooked, as are the flowers and root, but the plant is so uncommon that I don’t recommend picking it from the wild. The name “Oysterplant” comes from the taste of its leaves.

Several plants are described as “tasting like oysters”, including Salsify, which I have written about, and its close relative Scorzonera, but I’m not too convinced about the similarity.

The Plants for a Future website has a similar opinion of Oysterplant. “No-one has yet noticed a resemblance to oysters though not many of the tasters have ever eaten oysters! The flavour is fairly bland, the leaf is thick and has a very mucilaginous texture – it is probably this texture that reminds people of oysters.” I’ve eaten and enjoyed oysters a few times. It is the texture, combined with a fresh sea water saltiness, that defines the experience for me, rather than any strong taste.

But in “Flora Britannica”, Richard Mabey quotes a man in Scotland who has Oysterplant growing on his local beach. “I was once poisoned by an oyster and I can’t abide them. The taste of the leaf made me retch, so true is it to its name” (note 5).

The Edible Wild Food website says that “leaves can be added to salads, and they go quite well with eggs”. The Edible Garden Nursery website suggests that the leaves can be used “in fish dishes or salads.”

Oysterplant is often difficult to cultivate and is very susceptible to slug damage. Plants don’t like root disturbance and are most likely to succeed in well-drained sandy or gravelly soils in a sunny position. I haven’t tried growing it and I suspect it would be too hot for it here in Norfolk. However, if you like a challenge, why not give it a try? If you live in the UK, plants are available (to pre-order) from The Edible Garden Nursery. The Dave’s Garden website lists people in America and Europe who may be able to supply the plant. Oysterplant can also be grown from seed.

Other English names for Oysterplant include Seaside Bluebells, Sea Lungwort and Gray Oysterleaf.

Mertensia is named after the German botanist Franz Carl Mertens (1764 – 1831). The genus also includes American species such as Mertensia ciliata  (Fringed Bluebells) and and Mertensia virginica (Virginia Bluebells).

Notes

Note 1: The germination rate of seeds is increased improved by exposure to temperatures of 2°C or below. The British Wild Plants site is understandably gloomy about the plant’s return to Wales: “… the … seeds … must have a prolonged period in the cold sea water below 5C and then some time on cold pebbly beach in order to scrape the hard outer coat of the nutlets and allow germination to begin. The winter seas around Wales are far too warm now and it will probably never return.”

Note 2: The Flora of Svalbard describes three subspecies of Mertensia maritima. These are ssp. maritima, ssp. tenella and ssp. asiatica. Mertensia martima in the British Isles and New England is ssp. maritima, while ssp. tenella occurs in Svalbard. (I have been to Svalbard but annoyingly, I can’t remember seeing Oysterplant – I think I would have remembered if I had.)  Ssp. asiatica is found by the Pacific Ocean.

Note 3: Mertensia maritima is specfically mentioned in the MCCIP report “Impacts of climate change on coastal habitats” – L. Jones, A. Garbutt, J. Hansom and S. Angus (2013), MCCIP Science Review 2013: pp167-179. Climate change may lead to more storm surges, increases in temperatures and changes to rainfall (see page 172 of the report).

Note 4: The Churchill Barriers were built in the Second World War to protect Scapa Flow from enemy submarines and ships. They are now used as causeways to provide a road link from South Ronaldsay to Orkney’s Mainland, via Lamb Holm, Glimps Holm and Burray.

Note 5:  Richard Mabey (1996): “Flora Britannica“, Sinclair-Stevenson, London. Page 310.