Seed is a small embryonic plant enclosed in a covering, usually with some stored food. Seed germination is the process by which the seed embryo develops into a seedling. In order for a seed to germinate successfully three fundamental conditions must exist: (1) The embryo must be alive, (2) Any dormancy requirements that prevent germination must be overcome, and (3) The proper environmental conditions must exist for germination.
Different seeds have various needs in order to germinate. Some need light (press seed on top of the soil) while some need darkness (bury the seed in the soil generally 2 to 4 times the depth of the seed size) for optimum germination. While most seeds germinate easily, there are a number of varieties that are more difficult to germinate. These seeds will often have poor or even no germination unless a strict regimen is followed. So what can you do to get good germination? For the vast majority of the seeds we are selling if you ensure only the following three environmental conditions are made available optimally you will have your best chance to succeed with the seeds:
(1) Moisture, (2) Temperature, and (3) Sowing depth
Seeds need to be constantly moist in order to germinate. Do not let the growing mixture dry out or equally as important get too wet. Moisten the growing mix thoroughly before sowing. Stir the mixture with your hands to distribute the moisture. After the seeds are sown, place a cover or plastic wrap over your container to slow evaporation. Check every day for signs of germination and remove the cover as soon as you see a sprout so that the air can circulate around the emerging seedlings. Water with a fine spray. Over watering can rot the seeds and invite pests and diseases.
Germination is triggered within a temperature range that varies from one variety to another. Plants from winter areas, temperate regions, the arctic, high mountains and high deserts often germinate best at lower temperatures whereas plants from the sub-continent and warmer areas germinate best at relatively higher temperatures. Although warm temperatures will often speed up germination of seeds, but will lower vigour and survival. The seedlings will often be leggy if grown too warm. Please note that all temperatures mentioned are soil temperatures and not the ambient air temperature. Seed germination is all about soil temperature, so even if you suddenly find your area experiencing cooler or warmer temperatures, your soil may take a while to catch up to the temperature changes. If you don't have a soil thermometer (and most of us don't), remember that your soil temperature will usually lag behind your day/night average by as much as a two weeks or more. One thing to remember, also, is that the more shallow the sowing depth, the more quickly the soil temperatures will adjust.
Temperatures used in the website are, unless specified: Cold (1 - 5 °C), Cool (10 - 18 °C), Cool-warm (20 - 25 °C), Warm (26 - 31 °C) and Hot (32 - 38 °C). When no temperature is mentioned, Cool-warm (23°C average) is implied.
How deep a seed is sowed in the soil is a critical factor determining the germination success. Sowing too deep is one of the most common gardening mistakes. The embryo spends up all the reserved food before it can emerge out of the soil surface. As a general rule, cover seed with 2 - 4 times their thickness of soil, unless they require light to germinate. For seeds that need light, they must be sown at the soil surface or very gently patted down. Care must be taken to ensure that predators like insects do not eat the surface sown seeds. Sowing depth should also be adjusted with the seasons - sow shallowly in cold and wet, more deeply in hot and dry. Barely cover small seed, and sprinkle fine seed on the surface and water by misting. Lightly tamp soil to insure good contact with the seed, unless heavy. Plant flat seed edgewise and winged seed with wing uppermost or broken off.
In addition there are two other factors that can determine success with seeds.
Planting Medium: Seeds need water and oxygen to germinate, so are best started in a light, loose soil that will not compact, get soggy, or crust over. Free flow of water and air are a must. Many seeds do well sown direct to ordinary garden soil, but even good soil may be poor in pots and containers. These need a lighter, looser soil. It is best not to use the soil from your garden. Not only is it too heavy and provides poor drainage, you run the risk of bringing in weeds and garden soil will host some disease organisms detrimental to your seedlings. It is best to use a ‘soil-less mix’, if available. Otherwise, addition of some garden soil and compost will often ensure adequate beneficial micro-organisms. A good soil mix can be made at home from 1/3 garden loam, 1/3 peat or compost, and 1/3 coarse sand. Crushed charcoal also helps.
Light: Lack of light is probably the number one reason people get discouraged as seedlings grown in weak light will stretch, will have weak stems and often a pale colour. Seedlings need 12 - 16 hours of light from the moment they germinate. They also need at least 6 - 8 hours of darkness to process their food and grow. You will know if your seedlings need more light if they are pale and weak. If natural light is not available in abundance bring the seedlings in the room light. Mix the types of bulbs used since the cool white provides light in the blue/green range and encourages leaf growth, while a grow light or warm light provides light in the red range, which encourages flowering. This way you have a full spectrum of light.
So when can I expect the seedlings to emerge?
Average time from sowing seeds to the emergence of first seedlings is given for each product. Some seeds are quick to germinate in as little as under 24 hours whereas there are few that may take as long as a year or two! A seed that takes 2 - 3 weeks will usually come up fairly evenly; one that takes 4 - 12 weeks will tend to emerge irregularly. Time varies with temperature, so expect considerable variation. Don't give up too soon – many who have given up and sown another seed in the pot end up with two types of plants in the same pot!
Seedlings have started to emerge. What's next?
What about seeds that are difficult to germinate?
Over millions of years, wild plants have evolved germination strategies which ensure their survival, but which may not be convenient for the home gardener who wants a quick and even stand of plants from a packet of seed. Many seeds sprout irregularly, so that if the first flush of seedlings is killed by adverse weather, insect predation, etc., more will come along to take their place. Nature also prevents germination of all the seeds at the same time thus reducing competition for food, light and water. In adaptation to various environments, some seeds need periods of cold, warmth, darkness or light, fire, etc. Some have seedcoats of varying hardness or impermeability, and others contain chemical germination inhibitors which must be leached from the seed before it can sprout. Some species disperse themselves over wide areas by being eaten by animals, the seed sprouting far from the mother plant, the seedcoat softened by digestive juices. Many seeds have internal clocks, and give much higher germination at certain times of the year, regardless of the treatment given. Thus Nature has built in "Seed dormancy" for every seed. It is the reluctance of seed to germinate in a specified period of time under normally suitable conditions. All seeds wait for the correct time and conditions before sprouting, and the gardener must mimic those conditions to ensure successful germination.
Many seeds need special treatment to break seed dormancy and induce germination. Dormancy is highly variable. Sometimes a seed collected in the warm lowlands will germinate readily, but the same species collected at a high elevation will need cold. Dormancy even varies between individual plants at the same site, and varies with weather before harvest and conditions of storage after harvest. Some of the common techniques applied to break seed dormancy are:
We offer many seeds which are easy, and sprout quickly and evenly. But with some you must be prepared to experiment, be patient, and use your initiative and intuition. Remember that with some rare species, you are venturing into a relative unknown territory.
What are the common mistakes made during sowing of seeds?