Seed Sowing

Pelleted seeds are sown as normal seeds except they are normally sown on the compost surface.

Due to the pellets being very fragile, they are best sown direct from the phial.

Storing seed without losing seedling emergence potential needs carefully controlled humidity and

temperature conditions. Seed will not keep for long periods of time and remain in good condition. If you

have to store seed, place unopened packets in cold conditions.


The propagating area and equipment must be scrupulously clean. At the start of the season, wash down

and sterilise all benches and pathways etc. Make sure that watering systems and associated fittings do not

contain algae or contaminated water.


Whether using seed trays or modules, always use new containers each season. Many of the common

fungi which can affect seedlings can be carried over in compost which sticks to previously used trays etc.


Use fresh clean compost every time. Avoid temptation to reuse compost which has raised one batch of

seedlings. The compost should have an open structure and be relatively free draining. A specialist fine

grade seed compost, eg. Levington's F1 is best where nutrient levels are balanced for germination and

young seedling growth.

It is a good idea to use a pre-sowing fungicide drench on the compost. The main disease problems will be

from Rhizoctonia and Pythium which lead to damping off.


Fill the tray or module to level and tap gently to settle the compost. Water (or fungicide drench) the tray

thoroughly, using clean watering equipment and allow the compost to drain before sowing.


Sow thinly and evenly on the surface of the compost. Seed that is sown too thickly will be difficult to

transplant and root damage is likely. When hand sowing, aim to sow the required amount of seed in two

sweeps of the tray unless you are sufficiently skilled to achieve uniform distribution in one sweep. When

sowing by machine into plug units seed(s) should be placed centrally in the plug cell.


Not all seed requires to be covered, particularly items such as Begonia semperflorens or Lobelia which

have very fine seed. If in doubt, cover to the depth of the seed itself, using compost or a medium grade

Horticultural Vermiculite. This is recommended as it retains moisture during germination and allows

some light to get through once the seed coat has split.

High humidity levels should be maintained in the trays by either covering, eg. with polythene or placing

in a relative humidity of over 90%. If the surface of the compost is allowed to dry, then germination will

be affected. Some species will germinate best in the dark and, therefore, black polythene can be used,

remembering that this will absorb heat in some instances.


Temperature has a great effect on the germination process. Different species have different optimum

temperature ranges at which germination is best. Once outside the optimum temperature range, the

number of seedlings which will emerge from the seed is reduced. An air thermometer placed some

distance above the bench will not give an accurate reading for germination temperature. It is the compost

temperature at seed level which is important.


Check temperature and moisture levels daily. As soon as germination has taken place, remove any

covering and place in the light so that the seedlings do not become leggy.

Keep accurate records of sowing dates and early seedling growth in your own conditions. This will enable you to plan future

sowings and avoid bottlenecks at the transplanting stage.



Any chemicals referred to should be used only in accordance with the manufacturer’s instructions.

The Technical and cultural details are written for gardeners and growers, they are not cut and dried and are for information purposes only. It is not intended as a blue print for growing. A guide for you to use and adjust the data to suit your growing conditions. All information is based on UK conditions and should be used for guidance only. No guarantee is given for the resultant crop, or liability accepted for using the information used on this website in any article, web page or cd rom.