Crop rotation, perennial veg and legumes

1. RHS Level 2 Certificate
Week 20 – Outdoor food
production. Vegetables –
perennial vegetables and
legumes

2. Learning objectives
 1. Perennial vegetables
 1.1 state the place in seasonal rotation of asparagus
 1.2 state cultivation, propagation and care requirements of asparagus
 1.3 state 1 pest and 1 disease of asparagus, their symptoms and their
control
 1.4 state harvesting period and technique and storage
 2. Legumes
 For named varieties of each of runner and broad beans state:
 2.1 state the place in seasonal rotation and successional cropping
 2.2 state cultivation, propagation and care requirements
 2.3 state 1 pest and 1 disease of legumes, their symptoms and their
control
 2.4 state harvesting period and technique and storage
 2.5 explain nitrogen fixing and its importance in crop production
 2.6 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

3. Crop Rotation review
 Five main traditional rotation groups (salad
crops don’t fit into any of these – can form a
Misc. group with squashes, corn etc)
 Principle is not to use the same soil for the
same group two years running.
 One crop can benefit another – brassicas
follow legumes.
 Intended to keep down build up of pests and
diseases that are group specific.

4. Perennial vegetables - asparagus
 Not in a rotation
 Grown from crowns (roots with growing tip)
 Require good, fertile, well drained soil – a
bed can yield for 20 years so preparation is
essential.
 All- male varieties preferred – higher yield
 Pests – Asparagus beetle, slugs
 Diseases – Rust, Violet root rot.

5. Planting Asparagus
 Trench 20 -25cm deep
and 20cm wide
 Crowns spaced at 40cm
and planted on a
mound of compost or
rotted manure with the
roots spread out
 Ideally fill to about 5cm
above the crown initially
and then fill in stages as
the plant grows

6. Nitrogen Fixing - review
 Bacteria can ‘fix’ nitrogen gas from the air by
transforming it into a water soluble organic
compound
 Rhizobia live in nodules on the roots of legumes.
They provide the plant with nitrogen and the plant
provides the bacteria with somewhere to live. This is
a symbiosis
 The nitrogen is released to the soil when the plants
roots and green growth decays. So leave the roots
in the soil when clearing the legume crop and
compost the plants if they are not diseased.

7. Legumes – general points (1)
 With the exception of Broad Beans they are
half-hardy or tender so are sown late Spring
or earlier under cover.
 They need fertile soil but not additional
nitrogen. pH 6.5-7.0. Good drainage
 Many require support
 They fix nitrogen so are usually followed by
brassicas in the crop rotation

8. Legumes – general points (2)
 Manure or compost dug in the previous autumn.
 Prepare a Stale Seed Bed and incorporate a
balanced fertilizer about two weeks before
sowing (to allow time for the weeds to
germinate), water, wait, hoe off weeds.
 Sow in single drills at the required spacing and
depth or in broad drills as double rows.
 Can all be started early spring in pots or root
trainers under cover
 Watering is crucial at flowering and pod set.

9. Runner Beans - Phaseolus coccineus
 Prepare a bean trench – retains water and
improves the soil.
 Add a balanced fertilizer if the soil is poor –
but too much nitrogen = no beans.
 Put the support up before plantingsowing.
 Water – must be well watered or flower buds
will drop/tough, tiny beans.
 Weeds – particular issue when plants are
young, hand weed or careful hoeing.

10. A bean trench – ready to cover
with soil.

11. Pests and diseases – Runner Beans
 Pea and Bean Weevil – notched leaves and
tunnelled seeds. No chemical control. Start
under cover, hoe to expose pupae in
May/June.
 Bean Anthracnose – brown shrunken
patches on pods, necrosis on leaves, stem
cankers. No chemical control, sow resistant
varieties and do not save seed from infected
plants. Remove and burn diseased plants.

12. Broad Beans
 Hardy – so some can be Autumn sown.
 Support – none needed for dwarf varieties
(e.g. ‘The Sutton’) but Longpod and Windsor
varieties need support.
 No need for a bean trench
 Watering is vital, particularly when
flowerspods are forming and swelling.

13. Pests and diseases – Broad Beans
 Black bean aphid – on Broad Beans, remove
growing tip at four trusses; spray fatty acid
spray. Insect mesh – but must be there
before early May.
 Chocolate Spot – lift and burn affected plants

14. Learning Outcomes
 1. Perennial vegetables
 1.1 state the place in seasonal rotation of asparagus
 1.2 state cultivation, propagation and care requirements of asparagus
 1.3 state 1 pest and 1 disease of asparagus, their symptoms and their
control
 1.4 state harvesting period and technique and storage
 2. Legumes
 For named varieties of each of runner and broad beans state:
 2.1 state the place in seasonal rotation and successional cropping
 2.2 state cultivation, propagation and care requirements
 2.3 state 1 pest and 1 disease of legumes, their symptoms and their
control
 2.4 state harvesting period and technique and storage
 2.5 explain nitrogen fixing and its importance in crop production
 2.6 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