Seasonal Eating: What the Evidence Says About Taste, Nutrition, and Carbon
Seasonal produce often tastes better and costs less than imported equivalents. Growing evidence suggests it may also be more nutritious. Here's what the research actually shows.
The argument for seasonal eating is sometimes presented as pure romanticism - farmers markets, slower living, connection to the land. But there's a practical evidence base worth taking seriously. Seasonal produce typically costs less, because it doesn't require energy-intensive greenhouse cultivation or long-haul refrigerated transport. And there's growing research suggesting that phytonutrient content varies significantly with growing conditions and ripeness at harvest.
What Happens to Nutrients Over Time and Distance
Fresh produce begins losing certain nutrients - particularly water-soluble vitamins like vitamin C and folate - from the moment of harvest. Refrigeration slows but doesn't stop this process. A tomato imported from Spain and sitting in a distribution warehouse for four days before supermarket delivery and another two days before purchase has had roughly a week for nutrient degradation. A locally grown tomato harvested ripe and sold the following day has not. The difference in vitamin C content can be 15–30%, depending on variety and storage conditions.
Research comparing phytochemical content of conventionally grown produce found that compounds including quercetin, chlorogenic acid, and tocopherols varied significantly by season and growing conditions, with summer-grown outdoor vegetables showing substantially higher concentrations than their out-of-season glasshouse equivalents. [Hallmann & Rembiałkowska, Journal of the Science of Food and Agriculture, 2012]
The Cost Advantage
Seasonal vegetables in Ireland are typically priced significantly below their imported equivalents. In autumn and winter, Irish leeks, parsnips, celeriac, beetroot, and kale are among the cheapest vegetables available. In spring, asparagus and new potatoes drop to low prices. In summer, courgettes, tomatoes, and salad leaves follow. Buying according to what is genuinely in season is one of the most consistent ways to reduce food spending while increasing vegetable variety.
Ireland's Seasonal Calendar
The Irish growing season is shorter than continental Europe but broader than many people realise. Spring: asparagus, spinach, spring onions, new potatoes, rhubarb. Summer: courgettes, tomatoes, French beans, peas, salad leaves, cucumber, beetroot. Autumn and winter: leeks, parsnips, celeriac, kale, cabbage, Brussels sprouts, carrots, swede, and stored potatoes and onions. The brassica family - cabbage, kale, Brussels sprouts - is specifically well-suited to Irish growing conditions and available at excellent value from October through March.