Starting From Seed

Seeds come in many shapes and sizes. They can be as big as coconuts or as small as orchid seeds that are carried by the wind. Size usually depends on how the seed is dispersed.

Big or small they all have three things in common related to their structure:
1) Hard protective shell outside called the seed coat:
2) Dormant embryo inside;
3) Nutrition (stored food) to keep it viable. Viable means that the seed is capable of germinating when you plant it. If it is not viable the nutrition inside has been used up and the embryo will no longer develop. Much of seed viability depends upon storage conditions. Ideal conditions would be somewhere cool and dry (e.g. a capped jar in the refrigerator).

When a seed is planted in the ground, container, or any growing medium there are four environmental factors that affect germination:
1) Moisture - Germination begins with the absorption of water. It ends when the seedling is self-sustaining. During that period, the growing medium should stay evenly moist (like a wrung-out sponge) and never dry out.
2) Temperature – Seeds like warmth. Generally, 65-75 F is best for most plants. The back of the seed pack will list the desired temperature range.
3) Oxygen – Respiration takes place in all viable seeds. During germination, the respiration rate increases. Soil or growing medium needs to be loose and well aerated.
4) Light – Some seeds require light, some seeds require darkness, and for some seeds it doesn’t matter. The back of the seed pack will list any special lighting requirement.

Ideal characteristics of growing medium include the following:
1) Fine and uniform texture;
2) Well aerated and loose;
3) Free of insects, disease, and weed seeds;
4) Low in total soluble salts;
5) Able to hold moisture yet drain well.

If sowing seeds indoors in containers think about recycling egg and milk cartons, plastic soda and water bottles, or pie pans. Just remember to create holes in the bottom for drainage.

Seed Sowing Tips
1) Depth matters – Problems can arise if too shallow or too deep. In general sow seeds 4 times the smallest dimension (see seed packet).
2) In soil or in a pot?  Sow big seeds like sunflower, nasturtium, corn, peas in soil where they’ll grow.  Sow small seeds like broccoli, oregano, snapdragons in containers.
3) Re-sow seeds, especially of vegetables, every 3-4 weeks for continuously developing new plants.  This will provide sequential food crops to harvest. Plant lettuce in September, October, November and December, and you’ll have lettuce the entire school year.

Seed Diagram (Avocado)

How to Read a Seed Packet

The back of a seed packet lists all the information one needs to directly sow seeds in the ground. Let’s go through it item by item with this Cauliflower variety, Early Snowball and Carrot variety, Scarlet Nantes.

The Latin name isn’t always given but it’s a good idea to note the family name for rotation purposes. Brassica is the genus name, oleracea is the species. (See Making Sense of Botanical Names for more on proper name classification)

1)   Planting Depth - When we make a trench to lay our seeds the distance from the soil line to the bottom of the trench is the planting depth.
2)   Seed Spacing – Refers to distance in trench between seeds. With carrots its 3-4 per inch. Don’t overseed. It makes thinning later more difficult.
3)   Days to Sprout aka Days to Germination refers to the length of time between when a seed is first planted and when it first appears above ground.
4)   Spacing after Transplanting or Plant Spacing refers to the distance between plants once all thinning and transplanting has been done.
5)   Row Spacing refers to the distance between the rows. In school gardens we use mostly raised beds and not large fields in which these seeds are intended. The distance between rows in a raised bed can usually be greatly reduced.
6)   Days Until Harvest aka Days to Maturity is the time it takes to go from seed to table. Some will start from the day the seeds are planted while others use the day the seedling are transplanted to their final position.  Notice cauliflower takes 60 days however it is started indoors for 4-6 weeks. If we plant cauliflower directly in the ground our Days until Harvest will be 88-102 days.
7)   Misc – The following information is sometimes included but not always: light requirements, soil requirements, irrigation suggestions, when and how to harvest, fertilization requirements, and, growing suggestions.

Video - Germinator

A germinator is any device that demonstrates the germination process. The following shows how to make one.

Another germinator can be found here courtesy of RAFT (Resource Area for Teachers, www.raft.net)

Week 5 - Germination

Now that we’ve begun planting our seeds it is time to discuss germination. Germination is the process by which a seed breaks its dormancy, sprouts, and turns into a seedling. The best way to understand it is to observe it up close. In the classroom place some larger seeds like beans, pumpkins, peas or watermelon between layers of wet paper towel on a plate. Make sure the paper towel never dries out. It should feel like a wrung-out sponge. After a few days you will notice the root emerging.