Seed Starting Guide
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?
- Transplanting: If you did your planting in individual large containers, transplanting is not necessary. Seedlings in seed beds need to be transplanted when the first 4 true leaves appear. To transplant, hold the seedling by its leaves, not the delicate stem. Place into a pre-moistened container, slightly deeper than they were earlier. Firm soil around the seedlings, water immediately. Few plants do not like to be transplanted because of their root system. This is mentioned in the sowing and growing information of every seed variety we are selling.
- Hardening Off: Hardening off is basically getting the small seedling ready to face the harsh outdoors. At least a week before you plan to set the plants into the ground they need to gradually get used to the sun, wind and various outdoor temperatures. You can place your plants in a shaded, sheltered part of your garden for a few hours each day, gradually moving them into more sun.
- Thinning: The new seedlings need additional space to grow as soon as their first "true" leaves appear. It may seem heartless, but the weakest and spindliest seedlings need to be cut off at soil level so that the strongest ones can get stronger. If your seeding is rather dense, do not pull out unwanted seedlings as their roots may be tangled up and damage the root of the seedling remaining.
- Fertilizing: After transplanting, fertilize once a week. Over-fertilization can result in leggy seedlings. If the seedlings are starting to look leggy, pinch back the growing tips to promote more branching. This can be repeated every week or so to promote compact, bushy plants.
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:
- Scarification: Seeds with a hard seed coat need to be scarified to achieve good germination. This is done in 2 different ways. Smaller seed can be soaked in water 24 hours before sowing to soften the seed coat to allow for germination. Larger seeds need their coating gently abraded without harming the interior parts. While in natural conditions this coat would eventually be broken down, the impatient gardener can speed the process by using a knife or file to make a shallow cut. This allows moisture to enter and the seed to germinate.
- Leaching / Soaking: Provides two benefits – soften hard seed coat and also leach out any chemical inhibitors in the seed that prevent germination. Soaking for 2 to 6 hours in lukewarm water or overnight in water at room temperature is generally good enough. Soaking longer (more than 12 to 24 hours), especially in stagnant water, can result in oxygen starvation and seed death. Water should be changed daily for longer soaking.
- Pre-chilling / Stratification: Many seeds need a cold moist period before they will sprout. The essentials are moisture, air, cold and time.
- Soak seed overnight until swollen or soft (up to four days for large hard nuts). Nick if needed.
- Mix seed with about 3 times its volume of damp peat moss or vermiculite and place in a plastic bag. Small amounts may be conveniently layered between damp paper towels. Remember, air is essential; avoid sogginess. There must always be sufficient air inside the polythene bag and the medium should not be allowed to become dry. The polythene bag should be kept in cool temperature (15 to 18 °C) for 3 days and then kept in refrigerator for a designated length of time. Label the bag with the name of the seed and date to be removed from cold.
- Store in the refrigerator (1 - 5°C) for the time specified in the planting and growing guide.
- Remove the seed and sow. Seed is best kept cold (10°C or so) for a week after sowing, and gradually brought up to warm temperatures. Warming too quickly can be fatal for some seeds. Light is beneficial after stratification so pre-chilled seeds should have only a very light covering when sowed. Sow the seeds very close to the soil surface and cover the container with a sheet of glass or firm plastic layer in order to prevent them from common predators like birds. Despite stratification some seeds can stubbornly refuse to germinate until a year or more has passed!
- Plastic Bag Method: Best for very slow to germinate seeds, very tiny dust-like seeds that can't be allowed to dry out, and very slow-growing seedlings. Small clean pots are filled with damp, sterile, soilless mix. A light dusting with powdered charcoal discourages fungi and algae. Seeds are sown and the whole pot is sealed in a plastic bag and placed out of direct sunlight. This creates a mini greenhouse and the soil will not dry out and the seeds are protected from predators like birds, mice, etc. Pots can be left for years with no care other than regular checking for seedlings. As soon as seedlings appear, begin hardening off. Bagged pots may be kept under fluorescent lights without overheating. Don't forget to label!
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?
- Planting Too Deep: Seeds are very sensitive about how deep they like to be planted. Some seeds need complete darkness to germinate and some like some light. This information is in the planting and growing guide. To be on the safer side - don't plant your seeds in too deep. For seeds that need light to germinate, ensure that they are in contact with your seed starting medium, but not covered.
- Not Enough Light: Seedlings need a lot of light. No matter what anyone tells you, chances are that you don’t have enough natural light in your house to grow robust seedlings. You can also use artificial light or simply use household fluorescent lights and put in one warm white bulb and one cool white. Keep the lights as close to the seedlings as possible without touching (2 to 3 in.).
- Too Much or Too Little Water: Give your seedlings too much or too little water - either way they are dead. This is perhaps the most challenging part of growing plants from seeds. Because seedlings are so delicate, there is very little room for error when it comes to watering.
- Biggest Mistake: The biggest mistake in starting seeds would be to give up, even if you’ve made a few, or even a few hundred seed starting mistakes.