RHS Level 2 Certificate

Week 21 – Outdoor food production. Vegetables – root vegetables and miscellaneous

Learning Outcomes

1. Root vegetables. For named varieties of each of radish, carrots (early and main crop), potatoes (early and main crop), onions (spring, main crop and overwintering), leeks and beetroot, state:

1.1 state the place in seasonal rotation and successional cropping

1.2 state cultivation, propagation and care requirements 1.3 state 1 pests and 1 diseases of each, their symptoms and

their control 1.4 state harvesting period and technique and storage 1.5 Describe how quality and yield may be determined by the

following: base and top dressings, thinning, weed control, crop support, irrigation and pest and disease control

Root vegetables – general points

Root vegetables are discussed together but have particular and differing requirements.

Generally, apart from carrots, manure is applied when digging the plot the previous autumn.

Use a stale seed bed and apply a balanced fertilizer when preparing this.

Lime requirements vary depending on the crop. Watering is important and should be consistent –

lack of water leads to split roots.

Carrots (Daucus carota) Varieties

Round rooted – good for heavy or stony soil. E.g. ‘Parmex’ , ‘Paris Market’

Early – ‘Amsterdam Forcing’ Main Crop: ‘Chantenay’ Late Main Crop: ‘Autumn King’ Resistant to Carrot Root Fly: ‘Resistafly F1’

Carrots - cultivation

Dig the soil in Autumn but do not manure or add compost.

Prepare a stale seed bed, adding balanced fertilizer but do not lime.

Sow where they are to grow, carrots resent transplantation.

Sow in 1cm deep drills about 15cm apart, very thinly to avoid the need to thin.

Carrots – after care

Water regularly after germination. Irregular watering causes split roots.

Thin if necessary to 4-6cm apart. On a damp overcast day and remove all thinnings.

Keep weeds under control until well established. Use a mulch between the rows.

Control pests and diseases.

Carrots – pests and diseases

Carrot root fly – low flying insect lays eggs in the soil and crowns of plants. Control – barriers of fine mesh, nematode control available. Good crop hygiene at harvest.

Aphids – spread viruses so control by using fatty acid spray as soon as they are seen

Violet root rot – no control, apart from long rotation and crop hygiene, improve drainage.

Dwarf Motley virus – discoloured leaves and poor yield. Spread by aphids so control is to control aphids.

Potatoes (Solanum tuberosum) Varieties

Early: ‘Pentland Javelin’ Good disease resistance and some resistance to eel worm

Salad: ‘Pink Fir Apple’ Good flavour and unusual appearance, smaller yields than traditional varieties

Main Crop: ‘Cara’. Good blight resistance.

Potatoes – cultivation

Chit the seed potatoes before planting. Plant only certified virus free seed potatoes.

Do not lime – encourages scab. Early varieties – plant in March, main crop in April (provide

frost protection on cold nights) Water regularly at the base of the plants. Earth up when haulms are about 30cm tall to half their

height. Main Crop varieties benefit from high nitrogen and potash

liquid feed when the canopy begins to touch. No need to feed Early varieties

Potatoes - harvest

Harvest Early potatoes once they have flowered. They should be chicken egg sized. Earlies do not store well. Treat Salad varieties as for Earlies.

Main Crop – harvest once the haulms are dieing back (but do not leave too long because of late blight). Lift and allow to dry before storing in a cool, dark, dry place.

Potatoes – pests

Slugs – soil dwelling Keeled Slugs so pellets of limited use. Good cultivation and use nematode control.

Wire Worm – avoid planting on newly converted grassland. Use traps and cultivate soil well to expose the pest. Adjust planting times.

Potatoes - diseases

Blight – brown patches on leaves, dark spots on tubers which then rot. Grow resistant varieties, spray if necessary with copper fungicide. Avoid splashing the leaves of the plants when watering.

Mosaic virus – yellow mottled leaves, weak plants and poor yield. Control the aphid that spread the virus.

Alliums – general points

Need open sunny site – fine leaves Neutral to slightly alkaline soil Very vulnerable to weed competition – there

is even a special hand hoe called an onion hoe!

Need careful watering though the exact requirements differ for onions and leeks

Onions

Grow from seed or from ‘sets’ (specially grown and treated baby onions).

Need consolidated soil Pests and diseases – onion root fly, stem

and bulb eelworm, onion white rot Harvest – stop watering once leaves begin to

die back and shoulders are above ground, need to be lifted and allowed to dry before storage.

Leeks

Transplant into deep holes and do not backfill

Do not consolidate groundLiquid feed for mid-season varieties

mid to late summerHarvest as needed – mid and late

season varieties stand well into winter.

Learning outcomes

1. Root vegetables. For named varieties of each of radish, carrots (early and main crop), potatoes (early and main crop), onions (spring, main crop and overwintering), leeks and beetroot, state:

1.1 state the place in seasonal rotation and successional cropping

1.2 state cultivation, propagation and care requirements1.3 state 1 pests and 1 diseases of each, their symptoms

and their control1.4 state harvesting period and technique and storage1.5 Describe how quality and yield may be determined by

the following: base and top dressings, thinning, weed control, crop support, irrigation and pest and disease control