Roast chestnuts are a winter treat in central Europe which has spread to Finland in recent years. Attempts to grow the tree itself have probably gone on for centuries, but with poor results so far. It seems that no provenance will offer the hardiness required to grow the trees to seed-producing maturity.
But in recent years the specimen at Helsinki Botanic Garden has wintered without protection, and even flowered. A couple of seedlings received at Mustila from Ukraine have also showed signs of developing tree form. However, the climate will have to warm quite considerably before there can be any talk of chestnut production.
The leaves are long, narrow and toothed. The nut cases are prickly like those of the horse chestnuts, but the two species aren’t related. In warmer climates the sweet chestnut tree can grow into an ancient giant, like the oaks.
The chestnuts sold in Finnish supermarkets may also be the Chinese species C. mollissima, which is more resistant to disease and also hardier. Other Asian species and the American chestnut (C. dentata) could well be hardier in Finland than the Spanish sweet chestnut.