Forcing Winter Vegetables

Forced winter vegetables like this Belgian Endive in my garden may be the next hot food trend home gardeners and chefs haven’t  rediscovered yet.

Think about it – there was a time, and really not that very long ago  – like a hundred and fifty years or so ago, when there weren’t any supermarkets. There was no refrigeration aside from ice and no air travel so summer vegetables were just that – summer vegetables. Everything else was preserved, pickled, fermented or was considered storage vegetables, kept in a cold frost-free root cellar.

OK. We know that, right? But it’s not the truth.

Instagram is a good place to see where trends might be taking off. This Sea Kale (Crambe maritima) long valued by foodies in the UK seems to be becoming more popular, at least with chefs. Anyone looking for a luxury crop to try in North America still has plenty of opportunities to specialize if only they look to the past.

The fact is there were plenty of fresh veggies grown in the winter, especially if one lived near a large city like London or Paris in Europe, or in the Northeast in the US, for Boston was a leader in forced vegetables. Vegetables that were either sown in fall and raised under glass that was heated once the fuel furnace came onto the scene, or even more common, forced in hotbeds – cold frames specially designed to hold fresh, hot stable manure in a layer, and then covered over on cold nights with straw-filled quilts to hold the heat in.

My own roots of Belgian endive which are potted up in October and sprout in winter once brought into a warm, dark closet bring us the highest quality endives at the lowest cost.

Some crops like forced rhubarb were dug in the autumn and forced into growth in complete darkness in caves or root cellars producing a very tender and pale pink product which is still valued today in the UK for its quality which is said to be far better than that of conventional rhubarb.

Homegrown Belgian endive like these from 2 years ago are very easy. I dare say that it is the easiest vegetable to grow given the fact that it demands poor soil and drought in summer and little more than moisture and darkness in winter.

As we enter the Holiday season, I often think of forced winter vegetables because they still feel special in a world where most everything travels by air over great distances to get to our markets. We live in a time where we have the great luxury (albeit at a great environmental cost( of having fresh strawberries every day of the year. Few younger people even think about this, but fresh produce year round is a relatively new idea.

Or is it?

In 1900 many old books and magazines show rhubarb being forced in North America in cold frames and hotbeds as early as January. Remember, there was little fresh produce or fruit then aside from canned or home preserves. A Holiday meal with fresh forced rhubarb was a luxury item.

My mind was blown recently when I discovered that the asparagus I just saw at our local Wegmans for Thanksgiving (what? Asparagus at Thanksgiving?) was actually not an unusual thing in 1880. Really. Especially in the Boston area, where I live. Suburban Boston towns like Belmont grew what is known as ‘forced asparagus’ in hotbed and greenhouse throughout much of the 19th century along with tomatoes, cucumbers, and melons which were made available to posh Boston and New York markets via train. Delivery beyond 200 miles in the cold winter wasn’t practical, and this all ended by the end of the 19th century when transcontinental trains brought produce from the Westcoast, and when refrigeration by ice became more sophisticated.

A quicl search on Instagram shows that some UK farmers are revisiting the almost lost art of forcing rhubarb, which has a long tradition in Yorkshire where fresh winter forced rhubarb is preferred by chefs over sumer rhubarb. 

But even after 1888 when fuel-fired furnaces brought more practical heat to greenhouses and ranges could be built with steel and glass, the idea of forcing winter veggies continued to grow in the Boston area. Fuel meant that furnaces could create steam, and steam pipes could be set into pits, tunnels and in rows directly in the fields where asparagus was growing, to force it even earlier – often for Thanksgiving.

In the very early 20th century lettuce like any of the Great Lakes varieties were bred for growing in pots and sold in markets this way, before refrigeration – not unlike hydroponic lettuce sold today.

A book from 1917 by Ralph L Watts called ‘Vegetable Forcing’ presents all sorts of cropping methods, both old using stable manure to heat cold frames and hotbeds in which one can grow lettuce (Boston Lettuce actually came from Boston, and was an early forcing lettuce). I found it interesting that all early lettuce sent to market was grown in small pots, the root balls wrapped in waxed paper with a ribbon. Not unlike fancy hydroponic lettuce sold in markets today. Of course, before refrigeration – (and a time when those automatic misting devices at the market came along – with recorded thunder and tree frogs chirping!).

Lily of the Valley pips in this storage house is kept dark, then gradually grow quicker as warm temperatures are introduced.  I predict that the four-season market for Convallaria may experience a come back at least for flower farmers looking to extend their crops into the dark months.

The idea of forced winter veggies may be the next trend, after foodies have revisited Kombucha, heirloom tomatoes, the magic of fermentation, bread making, SCOBY, Kimchi and I guess – artisanal everything for that matter. The great local food movement is helping us understand and appreciate exactly where our food comes from and why ‘seasonal’ is generally considered better. Forced winter veggies fit right in. Who’s going to jump on this next? Surely there is a market for locally forced endive and winter, white Asparagus or pale pink rhubarb, sweet Sea Kale or forced celery.

In 1900, cucumbers and tomatoes were grown in winter greenhouses once steam furnaces became more practical, but before trains could bring produce from the south or west coast.

Even flowers can be forced, and I don’t mean branches. Lily of the Valley and French or Parma violets were once the most common Holiday flowers as along the Hudson River in New York farms with ranges of cold frames grew thousands of plants for the nearby cities. Maybe there are other crops too which have interesting stories. In Japan, I’ve seen winter-blooming peonies grown this way, with large flower in full bloom out in the garden even though it was snowing outside.

In Ralph Watts’ book from 1917, bees are shows being brought into a greenhouse in winter to pollinate cucumbers in Boston, or kept just behind a glasshouse with the advice to open a few panes of glass.

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