RHS Level 2 Certificate Year 1

Week 13 – Propagation by seed in practice

Learning objectives – Propagation by Seed

1.1 Describe the process of sowing seeds into a basic seed tray

1.2 Describe the preparation of suitable containers and growing media for sowing the following types of seed: fine, medium and large.

1.3 Describe appropriate methods of sowing seed in containers.

1.5 Describe the pricking out into containers, thinning out of seedlings sown in containers

1.6 Describe how the conditions for successful germination can be achieved in the open including the preparation of a seedbed

1.7 Describe appropriate methods of sowing seed outdoors including broadcast, sowing in drills and station sowing.

1.8 Describe the care of seedlings sown in containers and outdoors to include: provision of the most suitable environmental conditions; watering; the avoidance of pests and diseases; the control of THREE commonly encountered pests and THREE commonly encountered diseases.

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Seed propagation in a protected environment

Control of the environment means that the germination conditions can be optimised

Important factors in this control are the choice of growing medium, water supply, use of a propagator or heat pad, mist bench use and cultural hygiene.

Allows seeds to be started when outside conditions would not allow growth – particularly important for half hardy and tender annuals

Equipment

Containers – seed trays, modular trays, seed pans, Jiffy 7’s, root trainers. Seedlings often have shallow roots – so containers are shallow to avoid waste

Propagator – may be a simple plastic cover for a seed tray or a more sophisticated heated unit. Conserves humidity and temperature.

Heat pad – thermostatically controlled and placed under the seed tray.

Mist bench – commercial use, provides heating and misting.

Seed ‘compost’

Fine textured growing media, free draining but moisture retentive.

Little or no added nutrients – because these might scorch the roots as they emerge.

Heat sterilised – to avoid introducing fungal diseases.

Loam based or organic based – check pH if sowing pH sensitive species.

Multi-purpose can contain too much nutrient and be coarse. OK for large seeds.

Techniques for different sized seed

Very small seed – mix 1:3 with very dry silver sand and tap off your hand or from a fold of paper. The sand shows you where you have sown. Use a seed tray.

Medium seeds – tap off your hand or station sow (sowing individual seeds at controlled spacings) in seed tray or sow into modules (two seeds per module if germination rates variable).

Large seeds – e.g. Vica fabia sow individually into small pots or root trainers.

Sowing seeds into a seed tray

For small or medium sized seed. Aim is to provide a well aerated, free draining

but moisture retentive, even surfaced growing medium without large air pockets or lumps.

Sow thinly to avoid overcrowding (competition) and disease.

Sowing seeds in a modular tray or root trainers

Used for those plants which resent root disturbance or for medium and larger seeds.

No need to prick out so less labour intensive Takes up more space for fewer plants Unlike seed trays they tend not to be re-

useable. Can sow two seeds per station and remove

the weaker seedling to avoid gaps.

Pricking out

Required for seeds that have been grown in a seed tray.

Moves the seedlings from the seed tray into individual modules or pots to grow on.

Requires a degree of care and skill. Must be done at the right stage of growth or

the seedlings will become crowded and ‘leggy’ and there is the risk of fungal disease.

Pricked out into growing media containing some nutrients to sustain growth.

Pests

Aphids – chemical or biological controls (under glass)

Whitefly - chemical or biological controls (under glass)

Two Spotted Mite - chemical or biological controls (under glass), cultural controls especially heat and humidity (like things hot and dry).

Diseases

Damping off – seedling collapse. Control by hygiene and copper fungicide. Do not sow too thickly or over water.

Virus – control sap suckers, sow certified seed, destroy affected plants.

Downy mildew – no chemical controls. Hygiene, control humidity, grow resistant cultivars where available

Seed propagation outdoors

Used for hardy annuals, hardy perennials and many vegetables.

Cultivation – the aim is to produce a fine tilth Use of the Stale Seed Bed technique to reduce

competition from weeds Sow either broadcast or in drills – the latter makes it

easier to see which are weed seedlings. Keep watered and weeded, thin out to final spacing,

provide support and dead head ornamentals as the season progresses to prolong the display

Pests and diseases outdoors

Birds – use mesh barriers on vegetables, cotton between canes on new ornamentals.

Aphids – as for protected, but biological controls not used.

Slugs and snails – cultural controls, biological controls, hygiene, pellets (avoid metaldehyde).

Downy mildew –as for protected. Powdery mildew – requires dry conditions so water

correctly. Myclobutanil (Systhane). Virus – as for protected

Learning outcomes

1.1 Describe the process of sowing seeds into a basic seed tray 1.2 Describe the preparation of suitable containers and growing media for

sowing the following types of seed: fine, medium and large. 1.3 Describe appropriate methods of sowing seed in containers.1.5 Describe the pricking out into containers, thinning out of seedlings

sown in containers1.6 Describe how the conditions for successful germination can be

achieved in the open including the preparation of a seedbed1.7 Describe appropriate methods of sowing seed outdoors including

broadcast, sowing in drills and station sowing.1.8 Describe the care of seedlings sown in containers and outdoors to

include: provision of the most suitable environmental conditions; watering; the avoidance of pests and diseases; the control of THREE commonly encountered pests and THREE commonly encountered diseases.