Carrot Growing Masterclass: Perfect Carrots Every Time

Homegrown carrots are the last word in crisp, crunchy satisfaction. There’s an incredible range of fantastic varieties available and many of them are only available to the home grower - I mean, have you ever seen a purple carrot in the grocery store?

These ravishing roots are easy to grow so long as you follow these essential steps to success…

Best Carrot Varieties

Variety is the spice of life, and carrots have it by the taproot full! We’re all used to orange carrots, but did you know there are also yellow, red, white and – my favourite – purple carrots to sow and grow? This rainbow of roots can really pretty up the plate, while adding a touch of novelty to mealtimes.

Roots range from short and stumpy ones which are perfect for growing in containers or shallow soils, to the granddaddy of them all, the Imperator types, which can reach up to around 10in (25cm) long.

Carrots are divided into early and maincrop varieties. My tactic is to make a few sowings of early varieties in spring. These guys offer unmatched sweetness and are great in salads. Then, around midsummer, I’ll sow a maincrop carrot, which will give me chunkier roots to enjoy from autumn onwards.

Search seed company websites and catalogs to see what tickles your fancy, or seek out award winners for reliability and solid performance. These include RHS Award of Garden Merit winners Amsterdam Forcing 3, Eskimo, Flyaway, Maestro, Primo, and Sugarsnax 54.

How to Sow Carrots

Carrots prefer a sunny spot and, for the longest, smoothest roots, a well-drained, loose soil, free of any stones which could cause roots to split. Very rich soil (for example soil which has recently had manure added to it) can also lead to odd-shaped roots or multi-legged carrots. I get my fair share of comedy roots, but they’re all still perfectly good eating and can give you a good laugh too if you’re childish like me!

The earliest sowings can be made up to a month before your last frost date, or a few weeks earlier than under the protection of a greenhouse, tunnel or cloche. Carrots are best sown direct, where they are to grow, as they don’t transplant well. I sometimes see trays of carrot seedlings for sale, but I’d warn against buying them – they are unlikely to thrive and, if you work it out, the per-carrot cost is eyewatering!

Make your rows about a quarter inch (just under a centimetre) deep, with rows positioned about 8in (20cm) apart. The seeds are tiny, so they need to be sown with care, spacing them around a half inch (1cm) apart ideally. If you find the seeds tricky to handle you have a few options. Mix a pinch of seed with some sand, then sow pinches of this seed-sand mix – the seeds should land further apart this way, and it makes it easier to see where you’ve sown.

Alternatively, look for larger, pelleted seeds, or for seed tapes, which have the seeds spaced along the tape at the correct distance – you just need to lay it out in the bottom of the row then cover them over. I prefer to use normal seed because it’s cheaper and, with a little concentration, you can get the seeds reasonably well spaced, and they can always be thinned out later.

Carrots are quite slow to germinate, especially earlier in the season when they can take up to three weeks, so be patient. People often complain of patchy results but here’s perhaps the most important tip of all: you need to keep the seeds consistently moist until the seedlings emerge. That may mean watering every day in warmer weather, but it’s definitely worth it because if a germinating seed dries out it could fail. Steady soil moisture means smoother germination.

Early in the season you might need to cover your sown rows with glass or plastic to keep things a touch warmer until they sprout. If you garden somewhere that endures very hot summers, you’ll probably find it best to sow carrots from autumn through to early spring to grow through the cooler months.

In hotter weather I like to make life a lot easier by covering recently sown rows to keep them cool and shaded, which helps retain moisture. Wooden planks do the trick, or you could cover the area with hessian. Check regularly and remove you’re the cover as soon as the seedlings come through.

For a steady supply of carrots be sure to sow a row or two every three to four weeks, ending with some maincrop carrots for the winter.

Carrots are tricky to transplant, but if for you do need to start them off away from main growing area – perhaps somewhere a bit cooler in the heat of summer – then you can try sowing them into cardboard toilet paper tubes. Fill the tubes with potting mix, sow a few seeds on top then cover and keep everything nice and moist. The young plants can be set out at their final spacings, cardboard tube and all.

Unless you’ve got a very steady hand, you’ll likely have to thin the seedlings once they are up. This is an essential step to ensure enough space for the roots to reach their full potential. I like to thin in stages, initially to an inch (3cm) apart, then again in a few more weeks to leave plants 2-3in (5-7cm) apart. The later thinnings are rather elegant and can be used to pretty up a salad.

How to Prevent Carrot Fly

Thinning releases that delicious scent of carrots into the air, but caution’s needed or we’ll end up attracting the carrot’s nemesis, the carrot fly! Carrot flies approach their peak in summer, but I exercise caution even in spring because the flies can detect the scent of carrots up to half a mile away - which, I have to admit, is really rather impressive! When they home in on the roots, their larvae waste no time in burrowing straight on into them. No-one wants ravaged roots!

Keep your carrots under the carrot flies’ radar by thinning them on a still day, so the scent isn’t carried on the wind, and ideally at dusk when the flies are less active. Avoid bruising the foliage to release less of that carroty aroma, and water along the rows once you’re done to settle everything back down. Some gardeners prefer to snip the seedlings off at ground level to avoid disturbing the soil.

Another, possibly simpler, option is to keep carrots covered throughout their life with a row cover of horticultural fleece or fine insect mesh. Take time to properly secure the cover at the edges so that flies can’t get in at ground level. If you don’t like the look of covers try growing carrots close to allium family crops like onions and garlic, whose leaf shape and oniony smell may help to confuse the flies. Or try one of the several carrot fly resistant varieties such as Flyaway, Ibiza, Maestro, Parano, Resistafly, and Sytan, though bear in mind none of them will be 100% resistant.

While most carrot flies will come in from elsewhere, there’s always the risk of them overwintering where they settle, so I always make the effort to grow my carrots in a new area of ground each season as part of a simple crop rotation strategy. I can never remember what I sowed where from year to year – I can barely remember what I had for breakfast! – so to keep tabs on all this is to use our Garden Planner, which has a clever crop rotation feature that flashes red when you try to place a crop in the same area it grew in previous years.

Caring for Carrots

Be diligent with weeding to minimise competition, and keep seedlings watered in dry weather. Carrots need less watering as they establish – in fact, reducing how often you water can actively encourage the roots to grow down nice and deep in search of water, making them surprisingly tolerant of dry weather. Of course, if it’s been dry for an extended period then do give them a thorough drink, wetting right down into the lower soil, not just the surface.

Carrots normally flower in their second year, but most gardeners never see this because they’re harvested long before that. However very dry or hot weather can cause them to flower early, or ‘bolt’. Bolted carrots have tough, bitter-tasting roots which are no good at all. On the flip side, the flowers are incredibly pretty, and they’re a magnet for beneficial bugs, many of which will go on to control pests elsewhere in the garden, so it’s not all bad! I sometimes leave a few to grow on to flower for this very reason. If the carrot is a standard, open-pollinated variety you could always save some of the seeds for next season, but do be aware they’d need to be isolated from other varieties, including wild carrots, to make sure you produce the same variety.

Growing Carrots in Containers

Carrots are a great choice for containers. Sow them into pots that are deep enough for the roots to grow, or choose a stump-rooted variety. Sow into a multi-purpose potting mix (you can even reuse last year’s potting mix). Container carrots need watering more often than in-ground carrots as they dry out a lot quicker, so keep an eye on moisture levels as the weather warms up.

As well as enabling a super-early start under cover, containers can be raised up to keep them out of the danger zone of low-flying carrot flies. And I reckon with their frothy, ferny foliage, carrots in containers look pretty dapper too!

Harvesting Carrots

Knowing when to harvest carrots can be a bit of a guessing game, but there are some telltale signs. Look for plants with plenty of foliage, because this indicates a bigger root. If in doubt, I like to gently push back the soil to expose the very top of the root to check.

Harvest the biggest carrots first, leaving the remainder to grow on til you’re ready for them. It’s easier to lift carrots from moist soil. Another little tip is to push down on the root before you twist and pull it up from the ground. If you find roots snap when you lift them, just use a fork to loosen the soil first.

Once they’re up, twist off the foliage otherwise it will continue to draw moisture from the roots, causing them to go soft and spongy. I can never understand why ‘posh’ carrots in the shops are sold with their leaves intact, it just doesn’t make sense! That said, don’t waste the carrot tops – you can cook with these too, for example by whizzing up a tasty carrot top pesto to slather onto the roasted roots.

Early or salad varieties of carrot are best enjoyed before they get too big, because they’re sweetest when small. I try to use them as soon as possible after harvesting because the fresher they are, the sweeter they are – another delicious advantage over store-bought carrots.

I wash my carrots but never peel them because the outside of the carrot is where a lot of the vitamins are. Leave roots to dry off before storing them in the fridge, ideally in bags to keep them fresher for longer. Carrots can also be frozen after first blanching sliced rounds of roots in boiling water for a couple of minutes to help preserve flavour, colour and vitamin content.

Maincrop carrots are bigger, chunkier affairs that make them well-suited to lasting through the winter. In my milder temperate climate I can just leave them in the ground for much of the winter, to lift up as needed. They can be covered with leaves or straw to insulate them from the worst of the frosts.

In colder climates however, it’s best to lift your roots up in the autumn before the soil freezes rock hard. Brush or shake off the worst of the soil, cut off the foliage, then store only perfect, undamaged roots in boxes of damp sand or old potting mix. Keep them out of the reach of vermin in a dark, cool place such as a frost-free outbuilding.

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