Category Archives: Plant breeding

Growing and eating skirret

Never mind the Lost Crops of the Incas, skirret (Sium sisarum) seems to be the Lost Crop of the Europeans. Based on my experience, it’s high time it was rediscovered.

Originally from China, skirret was clearly well established in Europe by Roman times. It was a favourite of the Emperor Tiberius, a man who, don’t forget, could have pretty much anything he wanted for his table. He liked it so much that he demanded it as tribute from the Germans. It remained widespread and popular into Tudor times and then… where is it now?

Two crops of European empires may have displaced skirret. The first was the potato. Skirret is a starchy root, a useful staple, but nothing like as productive as the potato (what is?). The second was sugar cane. One of the most striking characteristics of skirret is its sweetness: even the name comes from a Germanic origin meaning ‘sugar root’. Before ubiquitous sweeteners, this would have made it extremely attractive, even to greedy Roman emperors. Whatever the reasons, skirret faded away from gardens, tables and popular consciousness. I’d say that it has several characteristics that make it worth revisiting.

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First up, skirret is delicious. It has a floury texture, a little like a potato, due to the high starch levels. Its taste is unique, but vaguely carroty, not surprisingly as it comes from the multi-talented carrot family (Apiaceae). It needs very little cooking. My favourite way of cooking it is to parboil for a few minutes, then fry in butter or vegetable fat. This gives a certain crispiness to the skin, encasing the gooey sweetness of the flesh.  Being from Central Scotland, I have of course tried deep-frying it and can report that it makes a passable chip, but it scores higher on taste than texture when cooked this way.

Secondly, skirret is quite easy to grow once you know how. Unlike most of its vegetable relatives it is not a biennial with a single taproot but a perennial that produces a whole shaggy bunch of roots. A dormant skirret plant can therefore be lifted, divided and replanted like any clump-forming perennial. Grown from seed, skirret produces a single ‘crown’: several shoot buds around the base of a stem, with a cluster of roots attached. Grown on, this crown will divide to form a clump made from several crowns. The clumps are easy to tease apart into individual crowns again. A cluster of roots will consist of several that are worth picking and a good number that aren’t, so my harvesting method is to dig up the clump, snip off the roots that are worth having, separate into crowns and replant. This leaves the plant with the maximum amount of resources for a good start the next year.

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A skirret clump

Thirdly, skirret ought to be an easy crop to improve. The combination of annual seed production and clonal propagation by the division of clumps means that new varieties are easy to produce and then maintain. The plants that I have grown from seed show considerable variation in root number, thickness, length and quality. I’d like to see skirret selected to produce fewer, fatter roots with smoother skin (cleaning skirret is something of a faff as the wrinkled skin tends to hold the dirt and require a good scrubbing).

One drawback to skirret is that the roots can have a woody core which cannot be softened by any amount of cooking and which is not particularly practical to remove. Guides suggest that this is a problem of young plants that goes away on older ones, or that it is caused by a lack of water while growing or that it is under genetic control and varies from one plant to another.

I have kept careful records of the qualities of my plants from year to year for the best part of a decade and I don’t think that the thing about older plants is true. Similarly, if there is a magic recipe for growing them without a woody core I am yet to find it. On the other hand there does seem to be a degree of consistency about how prone to woodiness an individual clone is, although this is accompanied by some year-to-year variation. I assume that genetic and environmental factors are interacting in unpredictable ways.

A second yield from skirret is the immature flower stems, which have a very nice carroty taste when boiled or steamed. They are fairly substantial and produced in reasonable volume, but they are fast growing and soon harden off, so if you want more than a brief harvest you will have to freeze some.

Starting skirret from crowns may be easy, but to get a crown in the first place you either have to shell out a fair bit of money or you have to start from seed. Skirret is not the easiest to grow from seed as like many of its relatives it needs a period of winter cold (stratification) to encourage it to germinate. If it is anything like most Apiaceae the seed will lose viability quite quickly, so it is a good idea to source current-year seed in autumn and start stratifying straight away.

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A single clump separated into crowns. The labels are to keep track of individual strains for plant breeding purposes.

For cultivation, skirret seems to like moist, free-draining soil in full sun. It’s said not to like hot weather but this isn’t a problem that I experience much. I’d advise growing it in rich, well-fertilised soil as a poorly fed skirret will produce thin roots that aren’t worth harvesting. Mature crowns need to be spaced at 30cm or more. Giving it a mulch is a good idea to help keep moisture in and suppress early weed growth. I have mine planted in a bed with compost dug in and a mulch of leaves over the top. It will grow up through the mulch and require little to no weeding as its strong growth suppresses weeds later in the season. Skirret can be left in the ground until needed: towards the end of the season, you might want to mark where the plants are as there can be little sign once the leaves die down!

The Joy of Promiscuity

This might sound like a rather abrupt change of subject for this blog, but no no, I’m still talking about vegetables, and any high jinks herein are purely plant-based. It does, however, begin with a seedy tale of contacts made on the internet…

A bit over a year ago, I offered some turnip-rooted chervil seed to members of a Facebook group I’m on. A few people replied and little packets duly went out. One recipient kindly sent me some kale seeds in exchange, along with a note explaining that they were from an OP grex. A quick Google later, I knew what an OP grex was. Essentially, a grex is a particular cross between two previously-named gene pools (which may be species or may be crosses themselves), plus any further offspring that arise from members of the grex crossing with each other or with the original parent populations. OP simply stands for open-pollinated.

Usually, seed-saving is quite a conservative affair. The aim is to propagate a named variety, keeping it as ‘clean’ as possible by avoiding pollination by any other variety. Seed-saving manuals give the isolation distance required for each species: up to a mile in the case of the brassicas. This keeps the variety stable, of uniform and predictable qualities. This is particularly important when one ancestral species has differentiated into a number of quite different forms: cauliflower and Brussels sprout will cross quite happily, but their offspring is unlikely to be very useful. The kale seeds I received represent a different philosophy.

The grex originated in a rare flowering of Daubenton’s perennial kale, pollinated by a number of adjacent brassicas. Since then enthusiasts have been breeding in as much diversity as they can. The idea is that individual growers can then select for whatever characteristics they like, according to local conditions and personal preference. If the long-lived characteristics of Daubenton’s are also selected for, this could eventually yield a galaxy of perennial kales, from super-cool Tuscan types to my personal hope, a perennial Pentland Brig.

kale panorama

Here you can see the diversity in a single row of OP kale, showing variation in leaf size, form, texture, coloration and yield. In the next generation, I’ll be selecting from this variety on five criteria: leaf size, yield, tenderness, funkiness and lifespan. Perennial kale is a great candidate for this approach. Uniformity isn’t particularly critical in kales: there are some of these plants that I won’t be breeding from, but none that are a waste of space.

Furthermore, a plant with a particularly good combination of qualities can then be propagated vegetatively by cuttings so that it is preserved. A number of other crops also have these characteristics: mostly ones which propagate by seed but also by bulbs or tubers. Most importantly, there is the potato. We usually buy ‘seed’ potatoes in bags of tubers from a single clone, but they also grow perfectly well from the seeds contained in the little tomato-like fruits that you may see on the vines. If you get a good one, it can then be propagated indefinitely from the tubers in the normal way. One variety I’m growing from is Magic Dragons, a very blight-resistant line that I was sent by Tom Wagner. The Kenosha Potato Project is an amazing network of true potato seed enthusiasts.

The alliums are another group with lots of potential. The problem with many asexually-propagated vegetables is that they slowly lose the capacity to produce seed at all, meaning that opportunities for future breeding are lost. Sometimes they can be coaxed back into seeding, as in the work that Kelly Winterton has done on potato onions (which are probably the same thing as shallots).

But why would you want to do this? Aren’t there proper plant breeders out there, honing the perfect varieties for us? Well yes, there are, but they can never hope to produce the range of locally-adapted varieties that an army of amateur enthusiasts can. Also, the nature of their trade means that they have to actively breed diversity out of their seed lines so that they are uniform and stable. Where this is a virtue, I’m quite happy to rely on the big guns to do the work, but where it isn’t, I’d rather have a joyous riot of diversity in my garden.

Big plant breeders are currently trying to claim rights far beyond a just reward for the work that they actually do, patenting not just individual mutations but whole broad characteristics of crop plants. This stifles seed sharing and the genetic heterogeneity that is essential for future resilience. The Open Source Seed Initiative is one response to this. Getting maximum diversity into seed lines is another, as explained in the excellent article Linux for Lettuce. Above all, it is simply so much more fun. The anticipation, interest and potential in my OP kale are simply so much higher than in any ‘clean’ variety I have ever grown. I’m now taking this approach to all the legumes and leaf crops that I grow too. I’ll leave you with a few more of those kales…

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EU threat to local seeds

I don’t usually use this blog to promote campaigns and petitions, but I think that this one is important enough to make an exception. On the 6th of May, European Union commissioners will be considering a new law which would make the sale or even the free distribution of unregistered varieties of seeds illegal. There would be a process for registering ‘old’ varieties cheaply, but this would still mean that the whole field of breeding locally-adapted varieties and unusual crops by amateur and small-scale local breeders would be outlawed. Forest gardening would be effectively nipped in the bud.

The Commission is divided on this, with the directorate of consumer affairs proposing the law and the directorates of agriculture and the environment against it, so national commissioners will decide the vote and there is a real chance to swing it. There is more detail on the Real Seeds Catalogue’s website.
Please write to your national commissioner, who is Baroness Ashton in the UK.  Her email address is catherine.ashton@ec.europa.eu. I’ve included the text of the email that I sent below. For other countries, the list of commissioners is at http://ec.europa.eu/commission_2010-2014/index_en.htm. Commissioners’ emails all take the form of firstname.lastname@ec.europa.eu

If you don’t have time to write, there are two petitions that you can sign on the Real Seeds page, but a clear, brief and polite personal email counts for a lot more than a petition signature. It needn’t take long: in fact short, clear and to-the-point is much better.

Dear Baroness Ashton
I am writing to ask you to vote against the new law on the sale and distribution of seeds proposed by DG SANCO when it comes up  for your consideration on the 6th of May.
As I understand it, the law will ban the sale or distribution of  unregistered varieties of seeds within the EU, with provisions for the cheaper registration of traditional varieties which are currently commonly traded. This will mean that plant breeding will become the sole preserve of companies rich enough to afford such registration. It will outlaw the huge amount of activity that currently goes on breeding locally-adapted varieties of a wide range of plants by amateurs and small-scale local producers. This activity has considerable economic and biodiversity significance, but perhaps even greater cultural significance.
In my case, I am involved in selecting seed of local wild species for use in forest gardening, an increasingly popular method of growing food in which shade-tolerant food crops are grown under fruit trees and bushes. Many of these species are only available in their wild form and would benefit from selection to improve their characteristics. An example would be sweet cicely, which produces an aniseed-flavoured root related to parsnip and which I am selecting for larger and straighter roots. I currently mostly give away seed but hope to sell some in the future. Both of these options would be outlawed by the proposed law.
It is difficult to see how this law would benefit anyone except for the seed companies which will gain an effective monopoly. It is surely significant that it is being proposed by the directorate for consumer affairs while being opposed by the directorates for agriculture and the environment.
Kind regards
Alan Carter

UPDATE.  In a very welcome development, on the 30th of January 2014 the EU’s Environment Committee voted unanimously to reject the seed law in its entirety, sending it back to the European Commission to be redrawn from scratch. This does mean that it will be back in some form or other, so the campaign is not over, but for now it is a major victory.

Off foraging, back soon

Work (and blogging) in the forest garden has had to take a back seat for a while as I’ve been overwhelmed by the amount of fruit and fungi to be picked out and about. There’s a close relationship between foraging and forest gardening in any case: a lot of the plants I grow in my allotment are ones that I could forage from the wild, given an infinite time and travel budget. Off the top of my head, the native wild plants growing in my forest garden include hogweed, sweet cicely, wild garlic, dittander, garlic mustard, sea beet, Scots lovage, buck’s horn plantain, common and musk mallows, Babington’s leek, Good King Henry, pignut, wild strawberry, various sorrels and wood violet. Oh yes, and raspberries, currants and small-leaved lime. A meal containing all of these would involve a week-long expedition taking in woods, heaths and coast – or five minutes in my allotment.

With every wild plant I have to weigh up whether or not it is worth giving it a place in the forest garden. Pluses are given for plants that I like and that are particularly productive. Minuses are for being too ‘spready’ or too big or for attacking me when I’m minding my own business, as with nettle. There is also the question of whether I have ready access to the plant on my foraging rounds. All these considerations are fairly individual, so the decision will be different for each person. I’m very much given to changing my mind: the latest one that I’m reconsidering is nettle, after talking to Fi Martynoga of the Scottish Wild Harvests Association, who was serving up out-of-season nettle brose at Wooplaw Community Woodland‘s 25th-anniversary bash. Fi has a patch of nettles is her garden that she cuts down several times a year to keep a steady supply of fresh new growth.

One species I’m still definitely leaving for wild foraging is the bramble (Rubus fruticosus agg.), a thorny, rumbustious plant that loves to romp around an area, pining dreadfully if it is restricted. I once saw some speeded-up footage of bramble growth on a David Attenborough programme. The briars thrashed around like groping hands; then, finding a purchase with their thorns, they surged forward. Take a look on YouTube and you’ll see why I don’t want them in my garden! We’ve just had the first flush of blackberries in Aberdeen. They are always the nicest so we’ve frozen what we didn’t eat and will make jam with a later batch.

cherry plum

Another fruit I have been picking, literally by the bucketload, is Prunus cerasifera, the cherry plum or myrobalan/mirabelle. I’ve raved about cherry plum before but well, I’m going to do it again. It is a mystery to me how neglected mirabelles are, seeing as how they produce curtains of tasty, juicy fruit and never suffer any disease problems that I have seen. True, any given cherry plum tree can produce fruits that are small, tasteless, sparse, unreliable, perishable or quick to fall from the tree, but equally I have found trees that carry fruit that is large, tasty and lasting, ones which crop reliably and ones which don’t drop their fruit at the first breath of wind. I’m sure it can’t be beyond the efforts of plant breeders to combine all these characteristics in one tree. Indeed there are some named varieties of P. cerasifera, available in the UK from Orange Pippin Trees. Has anyone out there had any experience with any of them?

There is an impromptu breeding experiment going on on a bank near my house, where there are perhaps a hundred cherry plum trees, probably planted with their blossom in mind more than their fruit. Their qualities vary wildly but some are very good indeed. I discovered one this year that has incredibly sweet fruits, even when still partly green. It is yielding so heavily that I picked a bucketful in less than half an hour. Right next to it is a purple variety that has proven itself to be an excellent keeper. I have been growing on seeds from the best varieties that I have picked for a few years now, so if anyone has a field that they aren’t using and would like to do a cherry plum trial orchard, I’m waiting to hear from you.

To add to the plum orgy clearly going on in these parts, cherry plums have evidently been crossing with my Japanese plum tree, Prunus salicina. I’ve been growing on seeds from it and some of them obviously have a variety of cerasifera called Atropurpurea as their pollen parent. Atropurpurea has been bred for deep purple bark and fruit and pink flowers and is unmistakeable. It is a rubbish fruiter unfortunately, but it suggests that other cherry plums will have crossed with the Japanese one too. Since the domestic plum arose as a cross between P. cerasifera and P. spinosa, the native sloe, who knows what will result?

Japanese plums ripening on a window sill

Growing pignuts

Pignut is a forager’s favourite, but not easy to grow. However, it has a number of pluses that make some perseverance and experimentation seem worthwhile.

So what are pignuts? Well, to science they are known as Conopodium majus, yet another member of the sprawling Carrot Family or Apiaceae. To generations of small boys and girls, they are known as the free treat you get if you painstakingly dig down where you see the distinctive leaves. Just recently they seem to have become a fashionable ingredient, starring in some seriously foodie recipes by chefs like Hugh Fearnley-Whittingstall.

pignuts

Pignuts have a lot of promise as a forest garden crop: they are extremely shade tolerant; they produce a starchy tuber, which is a bit of a gap in the forest garden repertoire; and they have a very pleasant taste and texture, a bit like a cross between a chestnut and a hazelnut. Unfortunately they also have several drawbacks, which I guess are what have so far prevented them from being domesticated like so many of their cousins.

The first is their life cycle. This isn’t a crop you sow in spring and harvest in autumn. In their first year of growth, they resolutely refuse to produce more than a single pair of leaves (technically the seed leaves or cotyledons, the ones which were always there, curled up inside the seed) even if growth conditions are perfect. At the end of the season they produce a tiny little overwintering structure called a corm, so small that you wonder what the fuss was about. The next year the plant throws up true leaves in about March but it may still take a few years for the corm to grow to a size worth bothering with.

roots and stems emerging from pignut corm

roots and stems emerging from pignut corm

The second problem is that pignuts like to bury their corms deep and then grow delicate, thread-like shoots up to the surface, making the harvesting of them quite an art. I think this is what makes them appeal to foragers, who are after all in it for the challenge as much as for the food.

Then there is the yield. The genius of pignut is that it can eke out a living, slowly increasing in a hostile tangle of other plants or in unpromising conditions. The drawback is that given a clear field and perfect conditions, it sticks determinedly to its slow and steady strategy.

pignut corms

So the good news is that if you get pignuts established in your garden, they will never need any attention again and you can occasionally dig up a pleasant treat. However, I can’t help thinking that a bit of selective breeding might produce something far more useful than this, getting round the difficulties but keeping the strengths. I’m currently growing a container full of pignuts, selecting for the size and shallowness of the corms. Since they take a couple of years to come to seed I haven’t had a lot of generations yet and can’t report any results so far, but watch this space.

The other possibility is that they could be cultivated in a way that gets round the limitations. Potatoes suffer a lot of the same problems, for instance, so we don’t usually bother growing them from seed (although you can: it’s quite easy and good fun) but instead just save a few tubers and replant them instead. It isn’t clear that the same is possible with pignut though. Instead of producing many tubers from one every year, it makes one corm, larger every year. I’ve experimented with cutting them into pieces, as you can do with potatoes, but they don’t seem to survive the process, and while potatoes hve many ‘eyes’ or growing points, pignuts have only one or a few.

A more promising line of experimentation seems to be to grow pignuts in a way better suited to their first-year growth habits. Instead of sowing out seed and having to weed the resolutely tiny plants, I sow them thickly in a tub of compost in autumn, then more or less forget about them for the next 18 months. In this time, they produce a mass of what I think of as ‘seed corms’ which can be sieved out of the compost and then sown almost as you would sow seed. An added advantage to this is that the corms stay where you sow them without getting any deeper, making them much easier to harvest.

Even grown like this, I don’t think pignut has the makings of a major crop just yet, but with enough selective breeding, who knows?

Cherry plums

Cherry plum (Prunus cerasifera) is described by Andrew Lear (a.k.a. Appletreeman) as ‘Scotland’s most undervalued fruit’ and I completely agree. It is just a little too big to have in my allotment, but I would definitely have one in a larger forest garden. Fortunately, in Aberdeen I don’t have to grow it myself as they are all over the place in my neighbourhood. It’s one of the first plums to flower, so it’s often planted as an ornamental, and it makes a good hedge (although don’t expect any fruit from it growing it this way), and abandoned hedges sometimes grow into dense rows of fruiting trees. Whatever the reason, there are long lines of cherry plums in my local park and behind the nearby botanic gardens.

cherry plum

Cherry plum fruit is very variable. With some you can clearly see the reason for the common name as they are no larger than cherries, others are more plum-sized. The colour ranges from yellow to a speckled red through to a dark, plummy purple. Taste and texture vary too, but in general they are nice, but not strongly flavoured for plums. They are generally poor keepers and have a habit of falling off the tree the second they are ripe (although again, this varies). This means that they are not the best eaters, although they are juicy and somewhat moreish when munched directly off the tree.

Where they really come into their own is when they are cooked. This seems to enrich the flavour and they make lovely jam. I usually make dozens of jars every year and it is easily my favourite jam. They often fruit very heavily, so it doesn’t take long to gather bucketloads. I’m sure you don’t need me to tell you how to make jam, so I’ll just pass on a couple of tips. Ripe cherry plums are soft and fleshy, so it’s easy to get the stones out of them before you cook up the jam. Either use a cherry-pitter or just use a sharp knife cutting down on top of the stone and forcing it out. This saves all that mucking about skimming stones off the top of the boiling jam. The other tip is not to add water to the recipe. Just put the sugar (I use about half the weight of the fruit) on top of the fruit (cut in half) in a bowl and leave it overnight: the sugar draws the water out of the plums and in the morning they will be floating in their own juice.
The cherry plums in our park have become very popular and these days I have to fight for a share. Here’s a recipe for cherry plum chutney from the park’s Facebook page.
Ingredients:

  • 900g plums
  • 2 medium onions – roughly chopped
  • 700g mixed sultana and raisins
  • 600ml spiced malt vinegar (or malt vinegar with a pinch of allspice)
  • 500g brown sugar
  • 15g ground ginger
  • ½ tsp cayenne pepper
  • 45g salt

Chuck everything in a big pan. Let it simmer for 40 mins until thick and jammy. Remove the plum stones as they rise to the top of the mixture. Spoon into hot jars and seal with lids. Makes approx. 5x 450g jars of delicious tasty chutney!

There seems to be a lot of confusion between cherry plums and another kind of plum called the mirabelle. This isn’t helped by the similarity of the alternative name for the cherry plum – myrobalan plum – to mirabelle. It is hard to be sure whether the similarity reflects the two words coming from a common source, representing long-standing confusion, or whether they just happen to be similar-sounding names from different sources (etymologies are given for myrobalan from Ancient Greek μυροβάλανος (murobálanos), meaning something like ‘juicy date’, and for mirabelle from Latin ‘mirabilis’). The two kinds do indeed look very similar, but the true mirabelle, Prunus domestica ssp. syriaca, is a much more southerly plant, flourishing mostly in the south of England on this island. Unfortunately the confusion spreads into the nursery trade, so it can be difficult to be sure whether what you are being offered is a cherry plum or a mirabelle. There are a few named varieties of cherry plum, such as ‘Gypsy’, ‘Countess’ and ‘Golden Sphere’. ‘Countess’ is a freestone variety, meaning that the seed is not stuck to the flesh of the fruit but separates easily.

Cherry plums grow easily from seed and I have been planting seedlings around the housing estate where I live to provide for the next generation of foragers. If you grow seed from a tree that you like, you have a good chance of getting a good tree, although unfortunately there is also a good chance of getting a cross with an ornamental variety such as ‘Atropurpurea’, which rarely make good fruit. They also seem to cross readily with my Japanese plum (P. salicina) tree, which has the same chromosome number (2n=16). Alternatively, if you have found a tree with good qualities, you can produce an exact clone by grafting cuttings. Cherry plum seedlings are widely available as hedging plants and could be used as rootstock, or you can use a standard plum rootstock like St Julien. Plums can also be cloned by detaching suckers (shoots thrown up from the roots), but in my experience cherry plums are less keen to produce these than other plums.

Finally, it used to be thought that domestic plums (P. domestica) were a cross between cherry plums and the blackthorn or sloe (P. spinosa), but apparently there is now evidence that P. cerasifera is the sole ancestor of all our domestic plums.

Japanese plums

Japanese plums

I harvested my favourite fruit today – Japanese plum (Prunus salicina) They look like the sort of plum you would get in the shops, with one subtle difference – they have flavour! Not just any old flavour, but the richest, most complex flavour I have ever come across in a plum, plus a juicy, melt-in-the-mouth texture. In fact, they are the same species as the hard, tasteless supermarket ones, but growing your own allows you to harvest them ripe and experience them as they really should be.

Nor are the virtues of Japanese plums limited to eating raw. They are surprisingly good cooked in savoury dishes: they are great frittered and the plum stir-fry season is one of the keenly awaited annual culinary milestones in my household. They also make an exceptionally good fruit leather, either on their own or in mixes with other fruit. My favourite fruit leather of all is pure Japanese plum with a little bit of ginger added. They can also be into thin strips and dried. The result is very tasty and stores well. On the other hand, Japanese plum jam is only okay – I think that tarter plums such as cherry plums generally make better jams.

Their all round deliciousness isn’t lost on the local wildlife and the big hazard with Japanese plums is that the birds and wasps will get them before you do. Fortunately, they ripen up well on the window sill if you pick them a few days early and that is what I generally do.

I am always surprised that Japanese plums haven’t become more popular in Britain. Perhaps it’s because most fruit guides will tell you that they aren’t very hardy here, but my biggest tree has been growing for over two decades in Aberdeen and fruits well every year. I strongly recommend seeking out the cultivar ‘Methley. which I believe my original tree to be. I have planted some other cultivars since, without nearly such good results. Unfortunately the two nurseries I have bought trees from in the past both seem to have gone bust, but Orange Pippin Trees sometimes have stocks.

Lime greens

small-leaved lime

There’s a new flush of leaves on the lime tree now. That’s lime as in Tilia, the one with the flowers that lime tea is made from, nothing to do with the citrus fruit. The limes are an interesting group – they are the only trees I can think of in the UK that have leaves worth eating more than one or two of for more than a few weeks of the year. After the first big flush of leaves in the spring, they have the very handy habit of producing a regular supply of a smaller number of new leaves. I’m growing them as a hedge to maximise the supply of new, reachable leaves.

All the different lime species have technically edible leaves: the big difference is that some of them are hairy and unpalatable, while others are smooth and slip down a treat. I originally had one of each of the native Scottish species. Tilia platyphyllos or large-leaved lime sounded great in the catalogue, but I found it bristly and almost completely inedible and eventually took it out. The smooth one is Tilia cordifolia or small-leaved lime, which Ken Fern of Plants for a Future describes as ‘the nicest lime I have tasted’.

I tend to agree, but the trouble with small-leaved lime is that, well, the leaves are rather small. The taste of small-leaved lime and the leaf size of large-leaved would be great and it just so happens that that isn’t an impossible dream, as there is a hybrid between the two called Tilia x europaea or common lime. Common lime is very variable, with seemingly practically every combination of its parents’ features out. A few that I have come across over the years have had the ideal combination of taste and smoothness. If a nursery wanted to take on the project, it should be possible to graft cuttings from such superior trees onto rootstock of other limes and propagate them. As its name suggests, common lime is very common, so it’s worth keeping an eye out for and testing out any tree within foraging distance of your home.

Limes are one of the best illustrations of a forest gardening principle that I call ‘The more you pick, the more you get’. If, instead of picking individual leaves, you nip of the whole leading end of the shoot, with one or two leaves attached, the tree is forced to break new buds further down the stem and you get new fresh growth. With continuous picking you can get a continuous supply of leaves from spring to late summer.

My limes came from the Agroforestry Research Trust, probably the most comprehensive supplier of forest garden plants in the UK.

Hard graft

grafted fruit trees

I was chuffed to see today that a couple of the fruit tree grafts I did this spring seem to have taken: both of apple (Malus domestica) ‘Red Devil’. I went on a grafting course with Andrew Lear, a.k.a. Appletreeman, in March, but I was beginning to worry that the skills graft hadn’t taken.

As well as the usual reasons for grafting fruit trees yourself (cheaper trees and the ability to propagate varieties that you like), I am interested in the technique for creating ‘own-root’ fruit trees. Own-root trees are ungrafted trees, that is, ones where the fruiting variety has its own roots rather than a rootstock, so you might wonder what grafting has to do with it. The reason is that fruit trees don’t usually root from cuttings, so you do a ‘nurse graft’, a normal graft with the graft union planted below the ground, using the rootstock as a sort of life support system for the scion until it can finally be coaxed into putting out its own roots.

Own-root techniques are based on the work of Hugh Ermen, formerly of the Brogdale Horticultural Experimental Station. Fruit trees are usually put on a rootstock in order to reduce the size of the tree and encourage fruiting by restricting the amount of nutrients available to it. The downside of the technique is that the resulting trees are less vigorous and more disease prone. Hugh developed techniques for propagation and inducing fruiting which allowed grafting to be dispensed with. His work is now being taken forward by Phil Corbett of Cool Temperate Nursery near Nottingham.

I’m interested in the technique myself because I do a lot of planting of fruit trees in public spaces, some of them quite rough. I think that own-root trees would be tougher and better able to stand up to the treatment they can get in these places. In particular, if they are broken off they come back true, whereas a grafted tree grows back from the rootstock. In the allotment I’m going to have to experiment with own-root techniques simply because my favourite fruit tree, a Japanese plum (Prunus salicina) came from the nursery ungrafted. It’s a vigorous, healthy tree, sure enough, but also going to get too big for its spot eventually. Then I will have to try coppicing it and seeing what the result is. In the meantime I have propagated it by layering branches, another own-root technique, and planted it out round the housing estate where I stay.

Radish, but not as we know it

First radish pods today.

I’ve never been much of a fan of radish (Raphanus sativa). The taste is so-so, you can only use so much of it in a dish due to its hotness and if you take your eye off it for two seconds it becomes hollow, woody and slug-chewed. However, when a friend gave me a few seeds of a variety described as having roots of a ‘uniquely lurid blue’, how could I resist?

The colour, a less-than-lurid brown, was a great disappointment and the plants ended up being left, unharvested, in the ground. As it turned out, that was when the fun started. Being a permanent experimenter, I started trying other parts of the plant. The leaves, fried a few at a time with a little salt, turn into brown crispy things that are so moreish that they rarely make it from the frying pan to the plate before being scoffed.

Radish seed pods are meant to be edible: these ones turned out to be very variable, ranging from woody, hairy, unpleasant tasting things to beautiful , smooth, succulent little vegetables with just enough bite to make them interesting. A few years of pulling up the undesirable ones and letting the others seed have left a strain that is reliably worth picking in quantity and freezing for use in stir fries, stews and pasta sauces. I have read that they are also worth pickling but haven’t tried it yet.

The strain has now found a place in the forest garden as one of the small number of annual species able to sustain itself by self-seeding in a perennial set-up. What has struck me the most about it is how quickly unnatural selection can work in some cases.