Eating rhubarb flowers

There’s an unusual perennial vegetable lurking unsuspected in many gardens at this time of year: rhubarb flowers. You should remove the flower stems from rhubarb to stop it wasting its energy on seed production in any case, so instead of chucking it on the compost, you could use it, as they do in the far east, as an exotic seasonal ingredient.

rhubarb flower stems

The secret to preparing rhubarb flowers is to know that the tiny individual flowers that make up the head do not contain any oxalic acid, the substance that makes rhubarb so sour, but the flower stem does. The stem is a branching structure that goes right inside the head so you’ll never get it all out, but if you just cut off the most accessible bits you’ll have got rid of most of it. Also be sure to remove the stem leaves, which are presumably as poisonous as the basal ones, and the papery bract which surrounds the flower head.

rhubarb flowers

The result is still sour, but interestingly rather than overpoweringly so. It goes best in dishes where there is a sour element and you can often leave out vinegar or lemon juice from a recipe in compensation. I find it delicious boiled for four or five minutes with broccoli sprouts, then drained and served with oil and salt over the top, leaving out the shake of lemon juice that I would usually add. It also goes very well in a stir fry.

Since a flower head will contain some stem and therefore some oxalic acid no matter how carefully you prepare it, it would be a bad idea to consume excessive amounts of them. This is also true of the rhubarb stems that are more normally eaten.

More on rhubarb in Rhubarb and elderflower jam, and a surprise.


Real spring onions

Last year was the warmest March on record: this year it has so far been the coldest. Spring ain’t what it used to be. None the less, it’s reliably time to harvest the ‘spring onions’.

I don’t mean the things you buy in the shops as spring onions (or scallions) since I don’t grow them. Let’s face it, onions are a pain to grow from seed. You need lots of added soil fertility and fanatical weeding of things that look regrettably similar to grass seedlings. Then, just as they are starting to look after themselves, you dig them up and eat them. By this time it’s usually August, which isn’t spring, not even here in Aberdeen.

tree onion

tree onion

Fortunately there are two perennial vegetable species which produce excellent spring onions even when it’s still snowing and with very little fuss for the rest of the year: tree onion (Allium cepa proliferum) and welsh onion (Allium fistulosum).

Tree onion is the same species as the ordinary onion. A lot of allium species can produce either flowers or tiny bulbs called bulbils (or both) in their flower heads and tree onion is a kind of onion that goes for all bulbils. These often sprout when they’re still on the plant, giving it a tree-like appearance. The stem then usually falls over, giving the plant another of its many names – walking onion – as the bulbils put down roots and the plant ‘walks’ around the garden. It also reproduces by bulb division underground, like a shallot or a daffodil.

tree onion divided

tree onion divided

This gives two ways to exploit tree onions for spring onions. First you can dig up the parent plant when it resprouts in the spring, divide out some of the bulbs and replant the rest. The other way is to gather the bulbils when they are produced later in the year and plant them out into a bed where they will grow on into very well shaped spring onions. It’s kind of like having a free supply of onion sets for spring onions and yet another name for this plant is ‘topset onion’ (You can also let them grow on into bulb onions, but they tend not to be very big.). You can plant some in the autumn for spring growth as they are extremely hardy but they will also keep well if you store them in a cool, dry place, so you can make successional sowings later on in the year too.

Welsh onion is a different species from regular onion but it’s very similar to tree onion. Instead of bulbils it produces a rather fleshy flower head which can also be used as a flavouring or left to produce seed (picking the flowers stops the plants producing seed and diverts their energy back into making bulbs). Like tree onions they divide underground and can be lifted and divided as spring onions in March and April.

welsh onion divided

welsh onion divided

Both species can also be harvested by picking leaves in the summer. I find that welsh onion makes bigger and more regular-sized spring onions by division and tree onion is better for leaves, partly because you can use the bulbils to produce a really dense patch. So the best use is probably welsh onions for division in the spring and tree onion for leaves and sets for growing on. If you allow welsh onions to flower you will be very popular with the bees.

Real spring onions can be used in all the same ways that you would use the seed-grown ones. My favourite is spring onion sambar: you fry a large handful of whole spring onions until they are soft, then add tamarind, coconut and spices to make a sauce and simmer for a few minutes. It’s a great way to forget the sleet driving at the window.

Daubenton’s kale – growing and cooking

Daubenton’s kale (Brassica oleracea var ramosa) is a perennial vegetable that seems to have everything going for it: tasty, hardy, productive and easy to grow.

I also grow nine-star perennial broccoli (Brassica oleracea botrytis aparagoides – actually a sprouting cauliflower) which is often touted as a perennial, but really it’s just a biennial that manages to hang on for a few more years if you zealously remove all the flowers. Daubenton’s, on the other hand, is the real deal, a perennial kale that usually lives for 5 or 6 years.

It seems that a lot more kales used to be perennial, but Victorian seed companies selected for biennialism in order to be able to sell the same variety year on year. A few old varieties have hung on by being passed from gardener to gardener, leading to a plethora of names such as Ragged Jack, tree collards, Woburn kale, Taunton Deane and many others which may or may not be the same as each other. Worse, some biennial varieties share a name with perennial ones having been bred from them. My all-time-favourite biennial kale is Pentland Brig; there’s a rumour of a perennial version out there which I dearly hope is true. In Germany there’s an ehwiger kohl (‘everlasting kale’ or, as Google Translate charmingly puts it, ‘eternal carbon’).

The bargain that Daubenton’s makes for its long life is that it is lived in complete celibacy. It is hardly ever known to flower [but see The Joy of Promiscuity], which means that it doesn’t exhaust itself, but adds a problem for the gardener: no flowers means no seeds, perhaps giving one reason why it is so rare. Fortunately, it is extremely easy to propagate from stem cuttings, particularly if you break off branches near the base. You’ll find some knobbles which are incipient roots. At most times of year you can plant cuttings or put them in water and the roots will start to grow. In autumn, Daubenton’s undergoes a brief hiatus when it slows its growth and sheds a lot (but by no means all) of its leaves. I’ve noticed that at this point its capacity to grow from cuttings is much reduced, so if you have failed to get them to root at this time of year, don’t give up. Another method is to layer branches by bending them down and burying a section. Over time the buried section will develop roots and make a new plant.

I got my first Daubentons in 2009 from Pépinière Eric Deloulay in France. He’ll deliver to the UK but there doesn’t seem to be an English version of the website, so you’ll have to scrape your secondary-school French back together or Google Translate it and run the risk of buying some eternal carbon by mistake. I got two versions, one green one with a red tinge to the leaves and another, variegated, one with larger leaves. The Agroforestry Research Trust now sell the non-variegated variety and Pennard Plants have both kinds. Cotswold Garden Flowers sell the variegated form (plants simply disappear from their list if they are sold out, so if it’s not there, that’s what happened). I’m often asked about suppliers in the US and Australia. I haven’t managed to track any down, but if you’re a supplier, or know of one, anywhere outside Europe, let me know and I would be happy to put up a link. If you are in the States, you might like to look at the ‘Kosmic Kale’ supplied by the Territorial Seed Company. This claims to be a new variety but it certainly walks and quacks like variegated Daubenton’s.

My original plants have now all died out but they have given rise to several generations of successors. A mature plant typically makes a dome about one metre high and wide and lasts for about 5 years. Winter hardiness seems to reduce with age and I usually lose some older plants over winter, but taking cuttings or allowing plants to self-layer seems to reset the clock. The worst cold my plants have had to face was -15°C one year, which they did with aplomb.

I have planted cuttings in various positions in sun and part shade (under an apple tree) and they have thrived in all of them. This ability to tolerate shade makes them ideal for my forest garden set up. They are also said to be very tolerant of soil conditions.

I use Daubenton’s pretty much wherever I would use an annual kale, in soups, stews and stir-fries.  In summer I mostly use it as a pot-herb, usually in a 50-50 mixture with sea beet. The kale takes longer to become tender than the beet, so you have to make sure it is cooked enough. In winter the leaves become sweeter and tenderer, enough that I start to use them in salads too. They are also ideal for kale chips (i.e. crisps).

Incidentally, Daubenton’s kale was named after the great French naturalist Jean-Louis-Marie Daubenton, a man who has had to suffer the posthumous indignity of English speakers constantly sticking an apostrophe into his name in order to make it look more French, so you’ll often find the plant referred to as D’Aubenton’s kale or even chou D’Aubenton. It’s also sometimes seen as ‘Dorbenton’, which seems to be an English phonetic spelling.

Eating hostas

One of my favourite seasonal treats from the forest garden is the hostas. No, no spelling mistake: hostas are really edible. In fact, they are a near perfect forest garden crop. Woodland is the natural habitat of many hosta species, so they like moist soil with plenty of organic matter and tolerate a considerable amount of shade. A friend tells me that they have a positive allelopathic relationship (i.e. they secrete chemicals that help each other) with apples, and since the research on it is published in Russian I’ll have to take her word for it. Hostas are no novelty nibble: they have the potential to be a major productive vegetable.

hosta clump

The best part of the hosta is the ‘hoston’, the rolled up leaf as it emerges in the spring, although many varieties are still pretty good even once they have unfurled. The best way of cooking them depends on the size of the hostons. Small ones are delicious if you fry them for a few minutes, then add a little light soy sauce and sesame oil. The slight bitterness of the hostons complements the saltiness of the soy sauce very well. Similarly, they go very well in stir fries. The chunkier hostons are better boiled briefly and used as a vegetable. In the picture below, the hostons on the right are bound for frying, those on the left are for boiling.


Hostons are best cropped by gripping them firmly near the base and snapping ones off the edge of the clump. If you can snap them off right at the base they will hold together as a whole instead of falling apart into individual leaves. The short leaf scales around the base are bitterer than the larger leaves so they are worth removing. It is much easier to harvest the hostons if the crown of the plant is a little above ground level when it is planted. It is possible to harvest the whole first flush of leaves of an established plant without killing it: ornamental hosta growers will sometimes ‘mow’ their plants to get a second flush of fresh, attractive leaves.

Later on, the open leaves can be used as a general pot herb or substituted for spinach in recipes like ‘hostakopita’. The flowers and flower buds are also edible: the Montreal Botanical Garden lists all species as edible and Hosta fortunei as the tastiest.

It seems to be an open question whether every single species of hosta is edible and therefore whether it is a good idea to try any unidentified hosta that you may happen across. The species I have eaten regularly myself are H. sieboldiana, montana and longipes. Martin Crawford lists H. crispula, longipes, montana, plantaginea, sieboldii, sieboldiana, undulata and ventricosa. Plants for a Future add H. clausa, clavata, longissima, nigrescens, rectifolia and tardiva and list no known hazards for the genus as a whole. This covers all the common ornamental species except H minor, which probably isn’t worth it anyway, and H fortunei, which must be edible since the most popular variety of it, ‘Sagae’ originally arose in hostas being grown for food in Sagae City in Japan. On the basis of that I’m happy to try any hosta myself, but if you’re going to do that, remember to try only a small piece first and test for a skin reaction by rubbing a piece on your skin before putting anything in your mouth.

Picture by ‘dcarch’ on the Seed Savers’ Forum

For more on eating hostas, there is a discussion and some astonishingly beautiful pictures of hosta dishes on the Seed Savers’ Forum. There was also a very useful article in Permaculture Magazine No. 58. It isn’t online unfortunately, but you can buy the back issue if you are really keen. A fellow wordpress blogger has also been writing about eating hostas here.

In Japan, hostas are prized as sansai or ‘mountain vegetables’, a class of plants that are usually gathered wild from the mountain and are considered to be particularly strong in vitality. There’s a great blog post about sansai at

Stop that plant!

ground elder

One thing you have to consider with planting a forest garden is how the plants you put in are going to spread, either by seed or by roots and runners. No matter how much you like a plant, you are unlikely to want it across your entire site. Strategies that stop your own plants from becoming weeds will also help stop out-and-out weeds like creeping buttercup which can otherwise spread through a perennial setup very quickly.

A lot of forest garden species just quietly sit where you put them, getting a little bigger every year and patiently waiting for you to divide them. These are the swots of the class. At the other end there are plants so unruly that it’s a bad idea to even put them in. Nettle is one of these. No matter how many uses this plant has and how good for wildlife it is, it’s just not getting in my garden again. It spreads by aggressive, persistent runners and seeds itself all over the place. Then, when you try to weed, it attacks you. This is one plant I will stick to foraging [2017 update: this turned out not to be true 🙂 ].

In between, there are plants that will try to spread, but that can be contained with a bit of care. There are various strategies for this. Vigorous spreaders like mint and dittander are best planted in a pot sunk into the soil, or you will quickly have far more of them than you are ever likely to need. It’s also a good idea to divide your plot up into beds using weed barriers. I have a good network of woodchip paths which are there as much as easily hoe-able barriers as for access. Sometimes a row of a particularly vigorous but non-spreading plant, like Russian comfrey, can make an effective barrier. Plants that die down early can leave a hoe-able strip behind them: I have a row of wild garlic that I use this way.

Once you have beds, you can match plants by their spreadability. Put all the well-behaved ones together, then corral the adventurous ones in a well-barriered ‘thug bed’ and let them sort it out between themselves. It’s useful to observe in nature which plants manage to come to an equilibrium with each other: this spring I saw a mixed swathe of nettles, ground elder, wild garlic and lesser celandine – all useful edible plants with marked imperialist tendencies – in the shade of a beech tree.

With this in mind, I have finally allowed Margaret Lear of Plants With Purpose to persuade me to try ground elder (Aegopodium podagraria) in my garden. I like ground elder, at least since I discovered that the way to eat it is to pick the only-just-emerged leaves and fry them in olive oil, but I’ve never wanted it in my garden. Margaret’s variety is variegated, so it should be a little less vigorous – and also easier to hunt down if I ever take against it. [You can find out how I got on with ground elder here.]

Welsh onion

welsh onion

welsh onion

It’s practically impossible to get a photo of welsh onion flowers without a bee getting in on the act. It’s one of the big pluses of forest gardening that a plant gets to go through all stages of its life cycle, with little lost compared to annual gardening except periods of bare earth and weeding. These stages are generally the ones that support more wildlife and the forest garden is full of bees, beetles and birds.

Welsh onion (Allium fistulosum) is nothing to do with Wales: the name comes from wellisc meaning ‘foreign’ in Old English. It is also known as Japanese bunching onion, which is equally a misnomer as it’s thought to come from China or Siberia. Whatever it says on its passport though, it grows well in Britain and is a very useful allium.

There are two ways of harvesting it. It grows as a clump which slowly gets bigger, so you can lift and divide it, replanting half and using the other half as spring onions or scallions. This is how it’s mostly used in Asian and Jamaican cuisine. Alternatively, you can just pull green leaves off it almost all year round, except when it is flowering or in a hard winter when it dies down. Some people like the leaves chopped into salads but I find the flavour quite strong and only use it for cooking.

Welsh onions put a good deal of energy into producing quite chunky flowers, but this isn’t wasted as you can use the flower heads too. Pick them while they are still young and green and nip out the centre. You will have a shower of tiny flowers that you can use anywhere you would use chopped onion. (But leave a few for the bees.)

Yellow day lily

Yellow day lily

Yellow day lily

The yellow day lilies (Hemerocallis lilioasphodelus) are in full bloom at the moment. The day lilies (Hemerocallis) are a very useful group. Some have edible tubers but the flowers are the stars. They go well (and pretty spectacularly) in salads, but I like the taste best in stir fries or soups. The Chinese use them to thicken soups and stews: you can see big bags of ‘lily flowers’ in Chinese supermarkets (but beware, some true lilies are poisonous – the perils of common names). They keep this property when dried, which they do pretty well themselves on the plant. Once dry they keep forever.

They yellow day lilies are always the first into flower with me: if you grow a range of species and varieties you can have fresh flowers for two or three months.