Carrots (Dacus carota var. sativa) are in the same plant family as dill and parsley (Apiaceae). They are relatively easy to grow preferring full sun, but coping with some shade, and like day temperatures between 15 and 20°C, particularly when young. Temperatures below 10°C can cause a more slender root, but they do tolerate greater variation in temperature as they mature.

Growing Conditions and Nutrient Requirements

Most varieties require sandy, light, deep soil that is well-drained but don’t plant on manured soil as this makes the carrots fork; save your manured soil for ‘hungry’ crops such as leafy greens and plant carrots after they have used up the excess nutrients.  

Dig over a bed that was manured for a previous crop. Or if you are starting a new patch dig over an area to about a spade depth and create a bed and raise the soil about 15cm or so, for good drainage, removing any lumps and stones. If you have heavy clay soil you try growing some in large pots or in a raised timber, or similar, bed.

Check the soil pH, if it is around 6.3 – 7.5 it is ideal, but do add some dolomite lime if the pH is lower than this. Although carrots don’t need too much nitrogen, they do like good levels of phosphorus and potassium; if you use a bed that was fertilised for a previous crop then this will be ideal.

 

Sowing Seeds

Although the vast majority of carrot varieties are sown during spring and summer, if you choose varieties carefully you can also sow a crop in autumn.
Rake out the bed to provide a nice surface for sowing your seeds.
Soak bed well before planting and keep moist until germination.

You can use a handle of a rake or a bamboo stake to create a shallow depression in the soil in which to sow your seed. Don’t make it too deep.

The seeds are small and fine; mix seed with a handful of sand to enable thinner sowing and less seed wastage (this also saves on thinning out carrots, which can attract carrot fly).

Sow the seed evenly along the depression and cover with fine soil. I like to use a soil sifter. I find it gives even coverage and you are less likely to ‘bury’ your seeds too deeply. Soil sifters are cheap and readily available through most hardware stores or garden centres. Press down the soil with your hands or use a flat object like a long wooden plank.
Make sure you keep the soil damp; carrot seeds resent drying out and your crop may fail if there is not enough moisture. It can take about 14 – 21 days for your seeds to germinate, once the seedlings have a set of leaves, thin them out to about 2.5cm spacing.

Caring for your Carrots

Apart from weeding and watering carrots need little other care, you don’t need to add dry or liquid fertiliser. Just keep the soil damp to ensure juicy sweet crops (dry soils produce woody bitter carrots).
Problems
Whilst pest and disease problems are relatively few, aphids, leaf hoppers and carrot fly can occur. Several fungal diseases can arise from time to time particularly in excessively wet conditions. If your garden has plenty of air-movement this should not be too much of a problem. Aphids can be washed off with a hose as you see them. Carrot fly is a bit trickier; water the soil straight after thinning and after harvesting carrots (the smell of crushed foliage attracts the flies) which then lay their eggs in the soil and feed on the fine roots later entering the carrots by boring into the them. Infected carrots are inedible. Carrot flies are low flying insects so to deter them, you could erect a low shelter around the carrot beds (insect proof netting or polyurethane, is ideal to a height of around 60cm).  Or try some carrots fly resistant varieties.

Harvesting

Carrots can be lifted at any stage of growth. In a home garden, thinning to allow some carrots to grow bigger will yield smaller, edible, carrots. To produce larger carrots harvest every alternate carrot when small, allowing the rest to grow on – you just keep doing this until you have harvested all of them. Most carrots store well in the soil (as long as it is well-drained) so harvest them as you need them and if the soil gets too wet later in the season, remove the rest of the carrots and cut off the foliage, making sure that you don’t damage the roots. Store the carrots in boxes in between layers of sand making sure that they do not touch and store in a cool, dry, dark place.

Varieties:

  • Short-rooted varieties are more successful in heavy or medium soils they also do well from autumn sowing.
  • Deep-rooted varieties require a deep, loose, and preferably sandy soil.

There are autumn sowing varieties suited to many regions however in cold areas – like those experienced in the UK - you may not be able to plant carrots in autumn. In moderate climates such as Australia and parts of New Zealand, choose suitable varieties.

A rough guide:

  •     Cool climate sowing times: to end of the first month of autumn.
  •     Mild climate sowing times: to the end of the 2nd month of autumn.
  •     Tropical climate sowing times: throughout autumn.

Here are some variety suggestions (not all may be available in your region but there will be alternatives):

  •  Any of the ‘Nantes’ varieties: shorter cylindrical varieties with good flavour.
  •  ‘Sugarsnax’ 25cm sweet carrot ideal for mid-autumn planting.
  •  All baby carrot varieties will do well in autumn – try ‘Little Finger’ and ‘Suko’
  •  ‘All Seasons’ as the name suggests does well in most areas throughout the year but may not germinate in very cold soils. Early autumn is ideal.