Seed Germination Set

Introduction

Preparing and germinating the seeds in this set will give students hands-on opportunities to learn about, and experiment with, the basic requirements for seed germination. Students will also observe and study the developmental differences between monocots and dicots—the two major classes of flowering plants.

Background

The seed germination set consists of four types of seeds: corn, barley, radish and pea. Corn and barley are classified as monocots—plants whose seeds contain a single cotyledon—while radish and pea are classified as dicots—plants whose seeds contain two cotyledons. The cotyledons are primarily food storage structures that also form the first seed-leaves of the developing seedling.

Basic requirements for germinating seeds include containers and a good seed starting/germination medium. Containers can be of a wide variety, including planting trays, seed flats or other shallow plastic containers, aluminum pans, clay or plastic pots and peat pots or peat pellets. Containers should be at least two inches deep.

A good germination medium is relatively light in weight, loosely packed and able to absorb and retain moisture. It should be (relatively) free of disease organisms and spores of molds and fungi. Recommended media include milled sphagnum moss, vermiculite (horticultural grade), soilless mixes (such as Jiffy Mix^®) and peat pellets. The milled sphagnum and vermiculite can be used alone, or for better results, combined in a 1:1 ratio. Peat pellets are convenient as they include both medium and container. Placing peat pellets or small pots in large trays or flats allows for bottom-up watering—an excellent way to minimize disturbance to delicate seedlings.

Materials

Procedure

1. Fill containers to within ½" of the top rim with starting medium. With the surface of the medium close to the container rim, ventilation (air flow) around the seedling is maximized, and shading of the seedlings is reduced. Prior to sowing, pre-soak the planting medium to avoid disturbing the newly sown seeds.
2. For small seeds, simply drop them on the surface of the germination medium and press them lightly with a fingertip. Cover loosely with up to ¼" of medium. Note: See Tips section for large seeds.
3. Once seeds are sown, cover containers loosely with plastic wrap, aluminum foil, damp newspaper or a pane of glass. This will help to maintain humidity and retain warmth.
4. Store plants at 75–90 °F (24–32 °C) to achieve ideal germination times.
5. Keep the starting medium moist but not waterlogged. Water from the bottom up (by placing containers in shallow trays) if possible—otherwise use a spray bottle to minimize disturbance. Watering with warm water will prevent lowering of the soil temperature.
6. When seeds have germinated and seedlings are visible, remove the covers and place the containers where they can receive natural sunlight or place them under “grow” lights. Initially, lights should be set 6 to 8 inches above the seedlings and subsequently raised as the young plants grow.

Teacher Tips

• Have students research the various characteristics of monocot and dicot seeds and seedlings. They can then dissect and observe seeds and seedlings to locate and identify contrasting features.

• Speed up germination of larger seeds by soaking them overnight in room temperature tap water. Sow seeds at a depth of up to three times their diameter.
• Germination rate (the percentage of seeds sown that successfully germinate) can serve as the basis for numerous experiments. Students can experiment with different germination media and media formulations, germination temperature and light exposure. Seeds show pronounced differences in time to germination at varying temperatures. For example, corn germinates in (approximately) 7 days at 67 °F (19.4 °C), 4 days at 77 °F (25 °C) and 3.5 days at 87 °F (30.6 °C). For light experiments, students can try germinating seeds in light, in darkness or at different wavelengths of light using colored cellophane as a cover over trays or containers.