Seasonal eating gets defended on four grounds: it is more nutritious, it tastes better, it costs less, and it is better for the planet.
Two of those are strong. One is weaker than usually stated. And one is mostly wrong in a way that matters, because it directs effort at the wrong thing.
Flavour: the strongest claim, and the least argued
Produce grown in its own season and picked closer to ripeness tastes better. This is not controversial and does not need a study — a tomato in August and a tomato in February are recognisably different objects.
The mechanism is straightforward. Produce destined to travel is bred and picked for durability rather than flavour, and harvested under-ripe so it survives the journey. Sugar development, aroma compounds and texture all suffer.
If you want one reason to eat seasonally, this is it. It is also the one most likely to make the habit stick, because it is immediately obvious rather than theoretical.
Cost: reliable and underrated
Supply peaks when a crop is in season, and prices fall. Sometimes dramatically.
This is the claim with no caveats attached, and it is probably the most persuasive one for most households — visible at the till rather than in an argument about micronutrient retention.
Nutrition: real but small
Here the case is weaker than it is usually presented.
Some nutrients do degrade with time and light. Vitamin C and folate are the usual examples, and produce picked ripe and eaten within days retains more of them than the same item picked early and stored for weeks.
But the differences are percentages rather than multiples, and they apply mainly to the least stable nutrients. Minerals and fibre barely move. Nobody develops a deficiency from eating out-of-season broccoli.
And frozen complicates the picture in a useful way. Vegetables headed for freezing are picked ripe and frozen within hours, which arrests degradation almost immediately. Fresh produce shipped out of season is often picked under-ripe and spends days or weeks getting to you. On the fragile nutrients, frozen frequently measures higher than travelled fresh.
Frozen is also cheaper, does not spoil, and removes the main practical barrier to eating vegetables at all — which is that fresh ones need using before they rot.
The honest hierarchy: eating vegetables matters enormously, and which form they arrive in matters very little.
Environment: the one that is mostly wrong
This is where the seasonal argument most often misdirects effort.
The intuition is that food travelling a long way carries a large footprint. The best available accounting puts transport at a small share of most foods’ total impact — commonly under 10%, and shipping is a small fraction of that. Production method dominates.
The consequence is genuinely counterintuitive: a tomato grown locally in a heated greenhouse can carry a higher burden than one grown outdoors in a suitable climate and shipped to you. Heating a greenhouse through a northern winter is energy-intensive in a way that a container ship, amortised across an enormous cargo, is not.
Air-freighted produce is a real exception, and it is a small share of what most people buy.
None of this means local food is bad. It means that if your goal is environmental, the leverage is in what you eat rather than how far it came, and in not throwing food away — household waste is one of the largest and most tractable levers available.
What it actually does well
The case nobody makes, and the best one: seasonal eating produces variety across the year.
If you shop what is in season, you eat differently in April than in October, and the range of plants passing through your kitchen over twelve months is much wider than someone buying the same reliable items every week. Dietary diversity is one of the more robustly supported patterns in nutrition, and this achieves it without anyone having to think about it.
That is a better argument than the micronutrient one, and it survives all the caveats above.
Practically
Buy in season when you can, mostly for flavour and price. Buy frozen without guilt, particularly out of season. Do not skip a vegetable because it is the wrong month. And if the environment is the goal, look at what is on the plate rather than at how far it travelled — and at what is going in the bin.
