Frances Michaels from Green Harvest Organic Gardening Supplies has these tips for sewing seeds.
Raising plants from seeds can be satisfying and fun. There are hundreds of varieties to choose from, far more than are available as seedlings. If you are growing vegetables this also gives you the chance to go organic from seed to plate, giving you complete control over what you are eating. There are new taste sensations just waiting to be discovered. Don’t be afraid to try seed raising, a bit of time and effort spent getting it right will reward you with a good germination rate.
A seed is a miracle of life. It is a tiny plant embryo combined with enough stored energy to bring it to life. The main requirements are moisture, air and warmth. The moisture softens the seed coat and allows the seed to swell. Air or oxygen can then enter and the seed begins respiration (to breathe), a process that releases the stored food energy of the seed and makes it available to the plant embryo. No fertiliser or light is necessary at this early stage for most seeds. The plant embryo has limited food available, it has enough to break through the soil surface, open its leaves and begin photosynthesis. It then immediately needs light and is vulnerable to drying out as it has started to grow. Fungal diseases may attack it, particularly if the soil mix is too wet or heavy. Air is vitally necessary in the root zone for successful germination and it occupies the spaces between soil particles. If the growing medium is too wet all the air spaces are occupied by water instead; if it is too heavy there is little or no air space available.
WHEN TO SOW
Always begin by reading the seed packet for directions.
A. GROWING SEASON
Timing is very important. Annual seed must germinate, grow and produce before the onset of changed weather conditions. Check the plant has sufficient growing time ahead. Warm season plants such as eggplants, capsicum and rosellas need 4-5 months frost free in order to produce. Cool season plants will 'bolt' (i.e. go to seed) in spring due to higher temperatures if sown too late. Information on what to plant now can be found in the seasonal Green Notes or the Sow When Poster. Local sources of information are very useful such as garden clubs or gardening columns.
B. SOIL TEMPERATURE
The soil or seed raising mix temperature needs to be at the correct temperature for the type of seed being sown. If the soil is too cold or too hot the seed may not germinate. Many vegetables, including beans, zucchini, melon, cucumber, tomatoes and capsicum, need a soil temperature of at least 20°C to germinate. Tropical and subtropical plants such as pigeon pea, rosella and winged bean need an even higher temperature to germinate successfully, over 25°C. Seeds such as carrot and lettuce will fail to germinate at high temperatures, over 25°C.
In cooler areas you may need to start seed earlier indoors as otherwise the growing season may simply not be long enough to produce successfully. It is disappointing to have a plant grow, flower and begin to fruit and then be cut down by the first frost of winter. To start seed earlier you will need to use either a bottom heat propagator or a hothouse. If this is not available you can try a warm windowsill, the top of a hot water heater or a Mini Propagator. Don't worry about the lack of light if your source of bottom heat is indoors. Seeds don't need light to germinate; in fact many germinate better in dark conditions (lettuce is the exception). Just keep a close eye on them and move them to a well-lit area as soon as they are germinated. Remember: air temperature is always warmer than soil temperature.
WHERE TO SOW
Deciding whether to sow seed directly into the garden, seedbed or into a container is a choice you need to make.
Article by Frances Michaels
Green Harvest Organic Gardening Supplies