The plot thickens - more space, new greenhouse

For the first time in my gardening life, I have a proper greenhouse. It's in reasonably good condition: a few panes need replacing and the beds inside need digging over and fresh soil. It's in a sunny position, aligned north-to-south as recommended for summer crops and I'm looking forward to raising aubergines, physalis, and I hope this year's pepinos dulces (Solanum muricatum, or melon pear).

The catch is that the greenhouse comes with 10 poles of abandoned allotment attached. Overrun with couch grass, bramble, bindweed and creeping trefoil, a preliminary recce has revealed that there are the remnants of raised beds underneath all this. It's a bit like I imagine archaeology to be: peeling away layers of cultivation. I think we have dug down to the 1980s so far.

Renovating the greenhouse and clearing the plot will have to be done in tandem. There are brambles and creeping trefoil roots rubbing up against the greenhouse frame and these will need to be taken out or else they will engulf the structure over the course of the summer.

After cutting down a bramble thicket out in the main area of the plot, I have abandoned plan A, which was to strim the plot then dig it over. I reckon it would break the strimmer. Instead, we (that's me and my son, who insists on being paid extra pocket money for this manual labour) have cut down the brambles, pulled up as much grass as will easily come away, and piled them all on to a bonfire, along with any rotting wooden raised-bed edgers we've found along the way.

We are building up a mighty pile of posts, stakes and even an old discarded radiator for the scrap metal merchant and an even taller pile of plastic for the skip. And starting one area at a time, we will cover the plot with woven black plastic. I've reserved one old bed that looks as though it was cultivated more recently than others to dig out and use this year, and I will almost certainly build a keyhole garden (full-sized, this time!) as a quick and efficient raised bed. Those and the greenhouse will do for this year. Everything else can wait.

By autumn, we can lift the plastic and get a much better idea of what we're dealing with, ready to hack out the perennial roots and hopefully start a no-dig system.

Salt-baked sweet potatoes

I'm mulling over whether to grow sweet potatoes again this year. On the plus side, they were less trouble than I'd anticipated, growing happily under a fleece cloche for most of the summer, even when I forgot to water them quite as regularly as they might have liked. On the minus side, the fleece cloche proved not very durable and were I to grow enough sweet potatoes for more than a few portions, they would take up a lot of space. I'm also wary that they grew well because we had a decent summer; in a more normal, cooler growing season, would it all be worth it?

I think I've decided to give it a go again thanks to a startlingly good salt-baked sweet potato I enjoyed the other day. I first encountered baking in salt with Anna Colquhoun and Mia Christiansen and their salt-baked celeriac.

That celeriac was a revelation: baked whole in a salt paste, the flesh was soft enough to be eaten with a spoon, with an intensely sweet celeriac flavour, salt-spiked at the edges near the skin. It's a bit of show-stopper of a dish: brought to the table still in its salt case and cracked open in front of the diners.

I wondered what other root vegetables might also taste good baked this way and after a bit of trial and error, found that sweet potato is exquisite when cooked in salt: the inherent sweetness of the potato is concentrated and the texture, after three hours in a low oven, is pillowy soft and fluffy.

I had good results with beetroot, too, especially the golden beetroot which are a staple of my allotment, but to get really soft and yielding flesh, it really needs to spend up to four hours in the 

oven. Sweet potato gives you a quicker return for your effort.

The trick is to ensure that the salt paste covers the potato completely: no gaps or holes. The paste needs to be made thick enough to hold its shape so that it doesn't all slump to the bottom of the dish as soon as you put it into the oven, but not so hard as to be un-malleable. As the sweet potato cooks, so the paste will harden into a rigid casing.




Recipe
1 large sweet potato, or 2 medium ones

300g cooking salt
280g plain flour
4 egg whites (this is a great way to use up spare egg whites)
Up to 200ml water

Scrub the sweet potato and dry the skin. Place it on a baking tray and pre-heat the oven to 150 degrees C.

Mix the salt and flour in a bowl and add the egg whites in the middle. Begin to beat together, adding the water a little at a time - you may not need it all. Stop when it's like wet Play-Doh - not thin enough to pour and not too thick to spread with a spatula.

Spread the salt mixture over the sweet potato, making sure the whole of the root is covered. Ensure there is salt paste around the base of the potato, so there are no gaps between the potato and the baking tray.

Put into the middle of the oven and bake for 3 hours. The salt paste will harden and turn brown as it bakes. When you remove it after 3 hours, it should be hard to the touch. Cut the top open with a knife, peel back the skin of the sweet potato and spoon out the flesh to eat.

The perils of the big bad bud

I inherited a couple of blackcurrant bushes when I took on my allotment. They were there already, flourishing and providing heavy crops of fruit each year without fuss. This means I never went through the process of researching varieties, which types might give the best fruits, or be the most pest-resistant. I just left them well alone and enjoyed the resulting blackcurrants, fresh from the bush, made into sorbet, and best of all, turned into crème de cassis (above).

This state of blissful ignorance also meant that I didn't spot that my bushes were falling prey to a mite known as 'big bud' (or Cecidophyopsis ribis, to give it its proper name). Or rather, I did spot it, but happily imagined that the swollen buds were just getting ready to burst forth with new leaves, rather than harbouring a wee pest. 

Inside each of the enlarged buds is a colony of big bud mites, microscopic creatures which feed on the sap in the developing leaves. Big bud does what it says on the tin: the winter buds are round and bigger than the unaffected ones, which are tight and oval. To the uninitiated (OK, maybe just me), the affected buds can actually look healthier. 

The big bud mite won't kill off your blackcurrant bushes, but the swollen buds won't open and so will stunt the growth of the plant. Big bud mites are also responsible for spreading reversion virus in blackcurrants which will severely reduce the amount of fruit the bush produces. The mites can also inhabit red and whitecurrants and gooseberries, though without causing the characteristic 'big bud' for which they're named.

Once it has taken hold, big bud can be difficult to eradicate. In summer, they will emerge infest new buds. They can be blown on to your bushes by the wind, but they are only really noticeable in the winter when you can clearly see the enlarged buds. There aren't any chemical sprays available to the domestic gardener which will be effective, and anyway, this seems like an overreaction; it's not as if the plants are in imminent danger of collapse. In the longer term you may have to replant your blackcurrants if/when they develop full-blown reversion virus.

In the meantime, it's not too onerous to check the plants a few times over the winter, removing the big buds by hand, and can be done at the same time as pruning. Just don't drop the big buds and lose them in the undergrowth. One is advised to burn rather than composting as well, to ensure that you don't end up breeding more bug bud mite colonies.

Further reading
RHS pest and disease pages: https://www.rhs.org.uk/Advice/Profile?PID=452
Big bud and reversion  disease in Which? magazine: http://www.which.co.uk/documents/pdf/blackcurrant-reversion-151472.pdf

Winter gardens

Even though it has its brave stands of leeks and the brassica bed is lush and green, the allotment does not look at its best in January.There are not yet any signs of spring on the way and every thing looks grey and downtrodden in the wet.

Time to raise the spirits with a visit to places which come into their own in the winter. My own outside space might be looking sorry for itself, but the winter garden at the Cambridge University Botanic Garden (above) sings with colour at this time of year and the winter walk at Anglesey Abbey (below) is at its most spectacular, And happily they are just a few miles apart and easily visitable in the same day.

Despite the rain, the colours of Anglesey Abbey's Winter Walk are vibrant

Relatively underplanting beneath Cornus sanguinea 'Midwinter Fire' hides the less colouful main stems. The silvery stems of Rubus thibetanus 'Silver Fern' make the beds look as though they have been sprinkled with frosting.

Contrats in form and colour with conifers and grasses at Cambridge University Botanic Garden.

The venerable Pyrus communis 'Pitmaston Duchess' espalier at Anglesey Abbey

The sun came out in the afternoon, bringing some welcome warmth to the woodland paths at Anglesey Abbey

Details
Cambridge University Botanic Garden
1, Brookside, Cambridge CB2 1JE
Open 10.00am-4.00pm January; 10.00am-5.00pm, February and March; 10.00am-6.00pm April to September.
Admission price: Adults: £5.00, concessions: £4.50; children under 16: free

Anglesey Abbey
Anglesey Abbey, gardens, and Lode Mill, Cambridgeshire, CB25 9EJ
Garden open 10.30am-4.30pm January to March; 10.0am-5.30pm April to October
Admission price gardens and mill: Adults: £7.10; children: £3.75

New for 2015: watermelon radish

I do like a good radish, from the fast-growing salad and snacking varieties to the long cylindrical winter radishes. With Amethyst and Cherry Belle, I can throw some seeds in a row between the parsips in March and be eating crisp, juicy bite-sized radishes with ice-white flesh in April. The firmer textured Hilds Blauer Herbst Und Winter or the darker-skinned Violet de Gournay bring a mustard-and-pepper flavour to winter salads and roast vegetables.

I was lucky enough to have dinner at Skye Gyngell's new restaurant Spring a month or so back. While Spring's setting in Somerset House is moons away from the dirt-floor greenhouse at Petersham Nurseries, the food is immediately recognisable as hers - many flavours and ingredients familiar from the Petersham Nurseries menu and from her books. And in a menu full of seasonal vegetables, I was introduced to the watermelon radish. Actually we misread the menu description and thought the dish contained both watermelon and radish, but no, this is a heritage variety of daikon or mooli radish. It's also known as Red Meat, but I can see why the restaurant would much prefer to use the watermelon name.

The watermelon appellation comes from its colouring: when sliced, each disc is a striking fuchsia-pink in the middle with bright green skin. It has a clean, firm texture with a satisfyingly snappy crunch, not too mustardy in flavour. Indeed, according to seed supplier Mr Fothergills, the flavour becomes milder as the plants mature - the direct opposite of most radish varieties.

Hilds Blauer Herbst und Winter - bright purple skin encloses bright white flesh.

This is a radish to be sown direct in early summer and harvested in autumn in the UK, slightly later than Hilds Blauer Herbst und Winter which despite the name I have sown in spring and harvested in summer. I'm currently finding this variety very hard to obtain - Mr Fothergill seems to be out of stock and I'm hoping the watermelon radish will fill the gap.

Suppliers
Watermelon radish aka Red Meat radish, or Pink Beauty
Mr Fothergills
Kings Seeds
Nicky's Nursery

Hilds Blauer Herbst und Winter
Mr Fothergills - out of stock

Violet de Gournay
Suttons

A gallery of pumpkins

When it comes to growing pumpkins, I'm happy to leave the cultivation of giant specimens to others. I've grown a few up to spacehopper size in the past, but it never seems to be the tastier varieties which grow really big. Football sized is about right - the green Berrettinas on the bottom shelf here are just a little but larger than that, and bowling ball sized - the green Futsus in the middle - will do just fine as well. 

I've also never got round to growing them on the compost heap, as others swear by, and which can give you highly productive plants as I noticed on my recent visit to Great Dixter. I start my squash seeds in pots and once they have at least two true leaves, plant them out in a bed with lots of organic matter - including kitchen compost - dug in. Before planting, I cover the bed with sheet plastic, and cut holes in it to plant the seedlings through - this keeps the moisture in and the weeds down. I also give the plants a mesh trellis to scramble up, which has two advantages: it keeps the squash plants more or less to the bed you planted them in, rather than rambling all over the allotment, and it means most of the fruits grow off the ground and are less vulnerable to slugs, snails, and rotting where the thin skin is laid on damp grass or soil.

In most years, the foliage starts to die off towards the end of September, and by mid-October, the fruits are laid bare across the bed - sometimes attached to the main plant by a mere thread. The squash will be ready to pick and bring inside then (squash ready for picking will also sound distinctly hollow when tapped). This year, with such a warm autumn, the plants stayed lush and green right through to the middle of October and I lifted them last week when our first frost threatened (frost will turn the pumpkins to mush).

Once safely indoors, they can be stored somewhere bright and warm - by the kitchen window, in my case - to be 'cured'. In warmer climates with longer growing seasons, pumpkins can be cured out in the field, but it's getting a bit chilly for that here in England now. Curing hardens the skins (which helps them to store for longer) and develops the flavour. You should really store the pumpkins for 10-14 days in the warm and then remove the fruits somewhere cooler, ideally at a steady 12 degrees Celsius or so, for storage, but mine stay happily in the kitchen window throughout the winter months. Those still uneaten after Christmas will store right through into the next spring.

Incidentally, I've never been quite sure which types of squash can call themselves pumpkins. Although we traditionally think of pumpkins as orange Hallowe'en lanterns, I would also call the Berrettina Piacentina and Marina di Chioggia here pumpkins, as well as other green varieties like Crown Prince. I've seen it suggested that one thing that distinguishes a pumpkin as a particular type of squash is that its seeds are edible.

Suppliers

Berrettina Piacentina: Franchi Seeds of Italy

Butternut squash: Organic Gardening Catalogue, Kings Seeds, Nicky's Nursery

Futsu: The Organic Gardening Catalogue

Marina di Chioggia: Franchi Seeds of Italy, Organic Gardening Catalogue, Kings Seeds

Quintale: Franchi Seeds of Italy

Spaghetti squash: Franchi Seeds of Italy, Nicky's Nursery, Victoriana Nursery

Great Dixter: a riot of colour

The wonderfully bold, lush gardens at Great Dixter look beautiful at any time of the year, but perhaps especially so at this time of this year, towards the end of an elongated summer with the air still full of warmth and the plants at full maturity. I was lucky enough to be visit on a gorgeous fine day last week.

A view of the oast house (sadly long out of use) from a corner of the sunken garden.

One of my favourite views, through the blue garden into the wall garden. I defy anyone to resist squeezing through the gap and exploring up the steps.

The impressively espaliered pear tree against the wall of the house in the blue garden (just visible in the top right in the previous picture). The Gunnera manicata in front of it is growing happily in a giant pot.

The seasonally-changing pot display in the wall garden is dominated by deep reds and brilliant yellows at present.

This is how to grow pumpkins on a compost heap - it helps if your heap is around 10 feet high.

A sneaky peek into the sunken garden from the meadow in front of the main entrance to the house. Great Dixter has many of these tantalising glimpses into its many gardens.

There are a couple of disused wells in the grounds, which now form stunning planters.

The main entrance to the house, which dates back to the mid-15th century, flanked by a mass of containers of lush flowers and those reds and yellows again.

Since the death of Christopher Lloyd, the owner of the Great Dixter estate, in 2005, the house and gardens have become a charitable trust, with the gardens  still overseen by Fergus Garrett, who devised the innovative and influential planting schemes alongside Lloyd.

The nursery, which sells many of the varieties grown in the gardens, is open all the year round. The house and gardens will reopen from March 28th 2015.

Further info from www.greatdixter.co.uk/