Carrots grow well in pots providing they are sown thinly and watered well. Any multi-purpose or seed-sowing compost will do or you can use growing-bag compost if this is cheaper.
GROWING IN POTS
The depth of the container depends on the type of carrot being grown, but roots are best harvested as baby carrots rather than trying to produce full-sized roots, unless you are growing in very big containers.
To sow simply scatter the seeds over the surface of the compost thinly, allowing half an inch or so between each. The idea is to thin these gradually, using the thinnings at baby carrots and allowing the rest to grow on. Water regularly and do not allow the foliage to wilt to avoid growth checks and split roots. Place the pots in a sunny place on the patio or similar but during hot weather shade the base of the pots from the full glare of the sun.
BEST FOR CONTAINERS
‘SUGARSNAX’: Long, thin deep orange roots that are great for deeper containers. Great as fingerling carrots.
‘RONDO’: Round orange roots similar to ‘Paris Market’. Fast-growing, it can be ready in as little as 42 days according to suppliers Suttons.
‘NAIROBI’: A quick-growing early/maincrop carrot with uniform roots.
BEST FOR RESISTING CARROT FLY
‘RESISTAFLY’: A Nantes type providing heavy crops. (Widely available)
‘FLYAWAY ‘: Good for shallower soils as it is sightly shorter than ‘Resistafly F’.
BEST COLOURED CARROTS
‘PURPLE HAZE’: Deep purple roots with contrasting orange cores.
‘RAINBOW’: Sweet roots in a range of colours from pale yellow to near red.
‘YELLOWSTONE’: Good flavour from long, tapered yellow roots.
‘SAMURAI’: Deep orange to red roots. High in antioxidants.
‘ARTEMIS’: Can be sown early or as a maincrop. Good flavour.
‘MARION’: A tender Nantes type with a deep orange colour.
CARROT FLY .There are two generations each year. The tiny flies are attracted to the crop by the smell of the leaves or may overwinter in the soil from previous crops to emerge as adults in May/June. They lay their eggs on the soil near the crown of the plants and the eggs hatch after a week. The larvae feed on the thin feeding roots eventually pupating in the soil and a second generation emerges in August/September and can act at a source of infection neat season.
Control them with barriers of fleece or crop protection material, try resistant varieties or grow your carrots in pots or under cover in an unheated polytunnel.
You can also use a biological control called Nemasys Grow Your Own and this will also control other soil pests such as cabbage fly.
APHIDS (GREENFLY). These pests spread viruses as they feed on the tender growth, often near the crown. Spray with a suitable insecticide as necessary.
SLUGS. Subterranean keeled slugs are the biggest problem. Some control can be gained with traps and barriers, but a biological control similar to the above called Nemaslug is useful since it is watered into the soil to reach the pests in situ.
SPLIT/FORKED ROOTS. Split roots often occur if the rows become dry and are then watered heavily or if rain occurs. Keep watering as even as possible and mulch around rows on free-drained soil. Forking often occurs on very stony ground or that which has been recently manured. Remove large stones or grow in raised beds or pots. Avoid sowing in recently manured soil.