Root vegetables and tubers
In this section contains root veg like carrots, salsify, beets as well as tubers that have not already been covered such as sweet potatoes and celeriac (celery root). Although similar in ways, root vegetables developed differently from all over the world. Carrots were cultivated thousands of years ago in central Europe (Switzerland and Germany area), whereas the radish originates from Asia and was brought to Europe by the Romans. Sweet potatoes come from central America and aren't actually a potato plant.
Young root veg plants are a draw for slugs and snails that will eat the plants at surface level, leaving some tell tale signs of fallen foliage. If you can, try to do an evening walk around with a torch and pick off any pests popping them in a different area. Due to the variety of veg plants here, skip down to a section you may be interested in.
Carrot, parsnip and salsify
These root vegetables are all a 'tap root' plants, meaning they have one main large root with a few small hair like shoots branching off rather than a fibrous root like legumes. Tap root veg require loose soil that is not compacted otherwise they will grow stunted and spiral.
There are two sowing windows for carrots, early varieties that can be sown January - March or that late varieties sown from March - June. Sow direct in soil around 1 - 2 cm deep and 10 - 15 cm (4 - 6 inches) apart. Some articles say to thin carrots, however, carrot root fly will pick up the scent and you may end up with a problem. If carrot fly are already an issue try solid garden shield/boards around 60 cm high as the carrot root flies cannot fly above that height. Alternatively, inter-plant with alliums, which seem to ward off carrot fly. Good varieties to try are purple haze, autumn king for soil or round types for shallow pots.
Sow parsnips from March - May 1-2 cm deep 15 cm apart. As these take longer than carrots you can sow a quick growing catch crop like radish, which can be picked within 4-6 weeks. By the time radish is harvested the parsnips will be coming through. Parsnips should be ready to pull up when the leafy tops die back from September/October and can keep throughout the winter as long as they are not waterlogged.
Salsify is more difficult to grow as it requires warmer temperatures to germinate that carrots and parsnips. Sow 2-3 seeds together (as the germination rates can be inconsistent) from March to May. This should be 2 cm deep, 10 - 15 cm apart. Salsify will be ready to pick from September until winter. Any plants left in may sprout flowers in spring.
Radishes, beets and celeriac
Radish is a quick growing shallow rooted crop with the exception of the mooli variety (sometimes called diakon) that can reach the size of a carrot. Mooli can take longer to mature that regular radishes. Sow year round, making sure that the soil is not frozen or too cold. If frosts and cold waterlogged soil is an issue in winter, growing them under cover throughout may be a good idea. Radishes will take 4-6 weeks to reach a decent size and slightly longer in colder seasons. There are plenty of French varieties that grow well, or for something different try radish watermelon.
Beetroot can be sown March - June around 1 cm (1/3 inch) deep and around 10 cm apart. Like radishes they will predominantly grow under the ground with the very tops of maturing roots poking just over soil level. The beet stalks are delicious and make a great garnish or part of a salad. Beets should be ready to pull from June - October. Chioggia are a popular variety or for something different try a 'rainbow' mix or the green blankoma varieties.
Lastly, celeriac (celery root) is grown for the bulb much like Kohlrabi. Sow from February - March for a summer harvest or September - October for winter. This root tolerates cold temperatures with winter frosts helping to lighten the flavour.
Sweet potatoes and yams
Sweet potatoes require much more warmth than potatoes so unless you are in hardiness zones 11-13, these need to be in pots in either a warm environment or a greenhouse. Sweet potatoes are grown from part of an existing plant called a 'slip' that are available at seed producers or garden centres. When you first get them soak in water to help them out (burying most of the slip) before planting out from May - June. If kept warm they can be harvested September - October.
Yams are a tropical tuber that can be mistaken for sweet potatoes, but can grow much larger. Yams are grown from planting a tuber in April and take up to 10 months to mature. You must live in a warm environment to grow yams, or keep them in a heated building.
Other tubers
Propagating cassava from seed is very challenging and inconsistent. It can be grown from a cutting of an existing plant and when established keeps producing plants. The plant itself grows rather large in sandy or lose soil but likes warmer areas that are not constantly moist. Set plants 1 m (just over 3ft) apart in late spring for a potential harvest in autumn.
Jerusalem artichoke tolerates the cold much better. Plant out tubers/plants from a garden centre from April - May. The plant should start to flower from July until August, looking like a sunflower. The red or white tubers should be ready to dig up in October - November. Alternatively you can plant in autumn for a slightly earlier harvest the following year.
Jicama is a tropical tuber from central America. It likes the heat and full sun so it may be harder to grow in cooler climates. Growing in pots with dry lose soil, which can be moved under cover may be an option but it still depends of your local micro climate. Sow the seed tubers from May and plant like potatoes placing 20-30 cm (8 - 12 inches) apart.
