- ly 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.