From Seeds They Start

Perhaps it is commonly believed that “plants grow from seed”, but actually growing from seed is only one means of plant propagation. A wide range of plants may be well established from seeds, yet many plants would demand other means of propagation. What would make us grow plants from seeds? That is the question that I will try to answer in my first post here.

The importance of planting from seed goes back to the following:

1. Preserving plant varieties and preventing their extinction by preserving their seeds and producing new generations by propagating from seeds.
2. Producing suitable root stocks in case of trees to be used for grafting by the desired varieties .
3. To avoid viral disease infection which is usually transmitted by vegetative propagation rather than seeds.
4. Plants which develop from seed have a stronger and more ramified root system than those produced by other means. Moreover, when planted in the right time, the emerging plants would be more tolerant to harsh environmental conditions especially droughts.
5. It is inevitable for propagating annual and biennial plants.
6. Good for producing more favorable varieties of new hybrids which result from cross pollination.

Growing from seed is not simply an act of sowing seeds into the earthy soil and watering regularly until the green shoots emerge. It is not merely an act of “dipping seeds into the soil”. That is why one may be in trouble when the sown seeds fail to germinate.

Before sowing, there is an essential step that many seeds require: breaking seed dormancy. This can be done by one of the following:

1. Stratification
It firstly requires soaking the seeds in water for 24 hours, then the seeds are spread over a layer of peat moss or sand in plastic or wooden trays . Then the tray must be kept in a refrigerator at a 5-10 degrees Celsius for a period ranging from few weeks to few months depending on the type of seeds.

2. Chemical Treatment
It is done by using sulfuric acid: H2SO4 or chemicals like: thio-urea, Potassium Nitrate. Also Gibberllin (GA) – a plant hormone – may be used to stimulate the germination.

3. Soaking in water
Soaking seeds in water would help the seeds get rid of some inhibitory substances. The water must be renewed frequently as the inhibitory substances may dissolve in the water.

4. Scratching
Some seeds, especially the hard and big sized ones, may benefit from some scratching.

Seeds can be sown directly in the field, or in seeding trays inside nurseries until it is later transplanted to the field. Sowing seeds greatly depends on the size of seeds; that’s why it is good to consider the following while sowing the seeds according to their respective sizes:

1. Small seeds: It is not advisable to cover the small seeds when sowing; they are simply scattered on the top of the seeding tray or soil surface. The soil inside seeding trays needs to be leveled, and after broadcasting the seeds it is good to press the surface by an even wooden block which will help keeping the small seeds attached to the soil surface. It is essential from there on that the tray be watered delicately by gentle spraying so that the seeds won’t be disrupted or dislocated.

2. Medium-sized seeds: These can be either planted individually in individual seeding pots, or cells, or together in a seeding tray. In their case they should be inserted into the soil at a depth which is equivalent to the seed’s length. So a half centimeter seed must be sown at a half centimeter depth.

3. Big-sized seeds: These are better sown individually, in pots, plastic bags or sown directly in the field at the required spacing. They also would be sown at a depth which is equivalent to their seed size.

Factors affecting Seed Germination

The germination time may vary depending on seed type and size; however, expect around 2 weeks for small seeds and between 3-5 weeks for larger ones. What if the seeds did not germinate after the expected time? Don’t panic, this does not necessarily mean that the seeds are dead. It would have different interpretations depending on the factors affecting the germination. A short answer is that there must be some factors that have inhibited the germination. Let’s look at them:

1. Water: It is essential that water penetrates the seed membrane and reaches the embryo so that the embryo would start feeding on the nutrients around it which would be activated by water. Hence, failure of water to penetrate seed coat may result in failure in germination.

2. Temperature: All seeds may require a certain range of temperatures where they would germinate. In general most annual seeds would favor a range of : 23-27 degrees.

3.Oxygen: The embryo needs air specifically oxygen to maintain respiration and eventually promote germination. Therefore, the seeding soil mix must be rich in sand and peat moss which would allow a lot of air space. It is essential that the soil be well aerated so that to avoid rotting as well.

4. Light: This also depends on the type of seeds you are growing. While a wide range of seeds may require some light, others would prefer darker conditions to germinate like lettuce seeds.

5. Growth Regulators: Some hormones, like Giberellin, are found to enhance germination, especially by breaking the seed dormancy as mentioned earlier.

6. Healthy soil: the soil must be clean -sterilized – and disease free.

Lesson learned from seed germination:

Think of a person who failed to accomplish something. This failure may not necessarily be due to factors inside him; more probably it may be because of some inhibitory factors around him. So it is like seeds who fail to germinate. It may not be because of the seeds; it does not mean that the seeds are not viable. They are viable- they have life in them- but you have to consider the medium around them.