It’s been a while since we’ve had a really testing winter in Aberdeen, so in an odd way I am rather enjoying the difficult one we’re having this year – as an opportunity to find out whether more recently acquired plants really are suited to growing in a forest garden in the north. We haven’t had any really deep freezes, but the continual back-and-forth over freezing point that we’ve experienced can be tougher for many plants than straightforward cold.
To start with those that definitely aren’t going to make it, I think I can firmly rule out milk thistle (Silybum marianum) for my garden. It was looking good after December’s frost and snow, but the extended cold seems to have been too much and all four of my plants are now withered husks. I’m also sad to report my mauka (Mirabilis expansa) as missing in action. This Andean root crop is widely described as growing in ‘cold, windy’ conditions at high altitude so it sounded perfect. My plants put on impressive aerial growth in 2016 but produced only small roots. I planted them in various positions around the garden to test out different conditions, but not one of them showed leaf again in 2017.
Some other plants have been putting on growth but are now looking like they are regretting it. Prime among these is alexanders (Smyrnium olusatrum), a surprisingly hardy plant given its southerly distribution in the wild in Britain. It always starts into growth very early in its second year and never seems to suffer for it. What has been fascinating this year has been the differing trajectories of two different two-year-old plants that flowered and seeded copiously in 2017. One followed this by dropping dead in standard biennial fashion. The other not only clung on to life but sent up a mass of new flowering growth in November and December. This is now being progressively cut back by repeated frosts, but if I had to take a guess I would put my money on it making it through to spring. I’ll be keeping a close eye on this plant to see how far its ambitions for perenniality go.
Another surprisingly hardy plant is globe artichoke (Cynara cardunculus Scolymus Group). When I started growing, received wisdom was that cardoon (Cynara cardunculus Cardoon Group), a variety of artichoke selected for stems rather than flowers, was hardier. That’s all very well, but I’ve never found cardoon worth growing and I’ve never met anyone who actually uses it. Fortunately it seems that globe artichoke is just as hardy after all and mine regularly puts on significant growth in the winter, seemingly unworried by getting cut down by frost every now and again.
Of my newer experiments, I’m glad to see that the Chinese mahogany (Toona sinensis) is looking unaffected by the cold. Not that I’m expecting a mahogany crop any time soon, but the tree’s young leaves have a spicy, oniony flavour that I’m looking forward to experimenting with more. My Ohio spiderwort (Tradescantia ohiensis) has not only been surviving but growing throughout the winter. I’m very keen to try it once spring comes and I’m not worried about weakening it. Creeping dogwood (Cornus canadensis) is not an entirely new experiment. I’ve lost several that I acquired as plants in past winters. This time I grew one from seed. It survived last year’s mild winter and seems to be looking good for this year’s harsher one, so perhaps I’ll get to try its fruit eventually.
The jury is still out on saltbush (Atriplex halimus). I had given up on this species after losing several plants over winter but decided to try again after finding a variety called ‘Cascais’ with larger leaves and shorter internodes – perfect for food production. Winter wet seems to be saltbush’s biggest enemy, so I gave this one a raised position on freely-draining sandy soil and crossed my fingers. So far it has suffered leaf scorch on a number of shoots but there is still a good bit of life in it, so I guess it will depend on what February and March throw at us. One advantage with saltbush is that it roots very easily from cuttings, so I have a backup copy on the kitchen windowsill.
Then we come to the real winter survivors. Land cress is the far easier relative of water cress. It grows throughout the winter and goes perfectly in land cress and potato soup, with the land cress leaves blended into a potato base at the last minute. Leaf celery (Apium graveolens) can be used similarly, and in many other ways besides. I’ll write a separate post about this under-rated vegetable soon. Kale (Brassica oleracea) is another great winter survivor, but I do find that the older perennial kales get the more susceptible they seem to winter cold. This is not only true of Daubenton’s kale but of Pentland Brig, an heirloom variety that has always shown a little bit of a tendency to survive an extra year or two. I’m told that in Florida this variety is genuinely perennial, but some of my three-year-olds are looking a bit touch-and-go this winter.
Salsify (Tragopogon porrofilius) and scorzonera (Scorzonera hispanica), two related root crops that can also be used for leaves and flower shoots, are both lasting well. Salsify is a biennial but it often germinates in autumn and then stands the winter. Perhaps the most unexpected winter survivor is wasabi (Wasabia japonica). Wasabi is possibly a little confused in this climate as it dies down and reappears at odd times, but it never seems too troubled by the cold.
I’m not entirely sure whether winters are getting milder or some plants are simply adapting to my garden. When I first grew leaf beet (Beta vulgaris) it generally died back over winter and only re-emerged come spring. This year many plants have been putting on significant winter growth. I must be on something like my eighth generation of self-seeded plants by now so it wouldn’t surprise me if there had been some selection for the conditions in my garden. I was also absolutely astonished to see a living rocket (Eruca sativa) plant. Rocket usually dies back at the first sign of frost. I’d be utterly delighted if it was getting hardier.
While some plants try to tough out the winter, others sensibly die back and wait it out undergound. While some of these won’t be seen again until May or June, others are more adventurous and quite a number are appearing already. Leading the charge is the onion family, including the chives (Allium schoenoprasum), Siberian chives (A. nutans), prairie onion (A. cernuum), German garlic (A. senescens), welsh onion (A. fistulosum), Sikkim onion (A. sikkimense), wild garlic (A. ursinum) and tree onion (A. x proliferum). They looked like they were regretting their rashness a little last week as blizzards swirled around them, but this is pretty normal behaviour for onions and I don’t think any of them will come to any harm from it. Only the three-cornered leek (A. triquetrum), which grew all through last year’s very mild winter, is looking decidedly unwell – perhaps not surprising for a plant more at home in the Canary Islands.
Then there’s the allium that laughs at winters, the queen of the Scottish vegetable garden, the leek (A. ampeloprasum). I have a range of perennial leeks, including elephant garlic, Babington leek and wild leek ‘Chesil Beach’ (which puts the song ‘Echo Beach’ by Martha and the Muffins into my head each and every time I see it), but perenniality is never far from the surface with leeks and many lines of cultivated, biennial leek occasionally form overwintering bulbs. This seems to me to be a promising route to new perennial varieties. For biennial leeks, I’ve tried many new varieties but nothing seems to beat the traditional ‘Musselburgh’ for winter hardiness and growth.
Other plants already showing a bit of growth include the sour-leaved garden sorrel (Rumex acetosa) and a very handsome bronze lesser celandine (Ficaria verna). There are even some mushrooms! Jelly ear (Auricularia auricula-judae) and oyster mushroom (Pleurotus ostreatus) both seem to be unconcerned by winter cold.
With some other plants there’s nothing I can do but wait a little longer to see if they re-emerge from underground hiding this year. One of those that I’ll be most interested in is myoga or Japanese ginger (Zingiber mioga). This survived last winter but failed to produce any of the flowers which are its only edible part. If it makes it this time I’ve promised it a move to a sunnier position.
Finally, I’ll share with you the ingredients of last night’s curry, sourced almost entirely from the forest garden, to show that there’s never a time when you can’t get some sort of meal from it. Harvested that day: leek, potatoes, yacon, celery, salsify, hopniss (Apios americana), sweet cicely roots and leaves, jelly ears, leaf beet, kale, wasabi and alexanders. From stores: oca, beans, neep and apple.