Germination 101

Cut open a seed and you’ll see a miracle. A tiny, embryonic plant waits inside, ready to break free of its seed coat, grow roots and push up through the soil.

Both internal and external conditions must be right for germination to succeed:

1. Water

• Most seeds are dry and need significant amounts of water—enough to moisten but soak them.
• Water uptake, called imbibition, causes the seed to swell, breaking the seed coat.
• The seed leaves, or cotyledons, contain food reserves for seedling growth.
• By the time the food reserves are used up the plant is ready for photosynthesis.

2. Oxygen

• Needed for aerobic respiration, which releases energy stored in the seed.
• Found in soil pore spaces.
• A seed buried too deeply can become waterlogged and oxygen-starved.

3. Temperature

• Affects cellular metabolic and growth rates.
• Optimum germination temperatures vary from species to species.
• Seeds have a temperature range and will not germinate above or below that range.

4. Light and darkness

• Can be an environmental stimulus for the germination in some species.
• Once the seedling breaks through soil, it requires light for photosynthesis.

5. Media

• Should be fine in texture.
• Should be of uniform consistency.
• Should be well-aerated and loose.
• Should be free of insects, disease organisms, nematodes and weed seeds.
• Do not start seedlings in garden soil, which is too heavy, does not drain well and isn't sterile.

6. Containers for germination and growth

• Peat pellets, peat pots or plastic bedding-plant packs can be used.
• Bottoms of milk cartons, cottage cheese, sour cream or yogurt containers can be used.
  • Make adequate drainage holes in the bottom of reused containers.
  • Sterilize reused containers before use: Wash in soap and water, then soak for five minutes in a solution of one part chlorine bleach to nine parts water.