By the end of the lesson, participants will be able to identify factors that influence seed germination, prepare seeds for germination, and care for seedlings in a permaculture garden in the tropical climate of North Queensland.
45 minutes
Greet participants and briefly introduce yourself
You can select plant varieties that are best suited to your area and soil conditions. Additionally, growing your own seedlings can be a cost-effective way to start a garden, as buying seedlings from a nursery can be more expensive. Raising your own seedlings also allows you to observe the entire life cycle of your plants, from seed to maturity, giving you a deeper understanding and appreciation of your garden.
Typically not a problem in North Queensland - though too much heat will kill the seedlings.
Adequate moisture is crucial for seed germination. Seeds need to be in contact with moisture to start the germination process. However, excessive moisture can lead to issues such as fungal growth, damping-off, and poor germination rates. The ideal moisture level for germination depends on the type of seed and the germination medium being used.
In general, the germination medium should be moist but not waterlogged. To achieve ideal moisture levels, it is recommended to water the germination medium from the bottom or use a spray bottle to mist the seeds. The germination medium should be checked regularly to ensure it does not dry out or become too wet. Covering the seed trays with plastic wrap or a humidity dome can help to maintain moisture levels during particularly low humidity periods (though usually not a problem if a sheltered area is selected away from wind).
Light plays an important role in seed germination as it triggers the production of chlorophyll, which is necessary for photosynthesis to occur. Some seeds require light to germinate, while others need darkness, and some may not be affected by light at all. Light requirements for germination vary depending on the plant species and the environment. In general, seeds that require light for germination should be planted near the soil surface or left uncovered. Seeds that require darkness should be covered with soil or other opaque materials to block out light. Insufficient light can cause seedlings to become leggy, weak, or discolored, while too much light can lead to overheating, dehydration, and stunted growth.
The quality of the soil or growing medium used for seed germination plays a crucial role in the success of germination and growth of seedlings. Seed-raising mix is specially formulated to provide the ideal conditions for seed germination and early growth. Seed-raising mix is typically a combination of peat moss, vermiculite, perlite, and other organic matter. A good seed-raising mix should have good water-holding capacity, adequate drainage, and aeration to promote healthy root growth and prevent waterlogging. A pH level of 6.0 to 7.0 is ideal for most seeds, but some may require a more acidic or alkaline soil.
Seeds lose viability over time due to aging, exposure to heat, moisture, or light, and other factors. Old or low-viability seeds may take longer to germinate, have lower germination rates, or fail to germinate at all. The seed germination test can be done using a paper towel, soil, or other germination medium. The test should be conducted in a warm and humid environment, and the seeds should be kept moist but not waterlogged. After a set period of time, usually 7-14 days, the number of germinated seeds is counted, and the germination rate is calculated. A germination rate of 80% or higher is generally considered good, while rates below 50% may indicate low seed viability. Seeds that do not germinate can be discarded, and only the viable seeds should be used for planting. It is recommended to store seeds in cool, dry, and dark places to maintain their viability and extend their shelf life.
Soaking seeds can be a helpful technique to improve germination rates, especially for seeds with hard or thick seed coats. Soaking seeds helps to soften the seed coat, allowing moisture and oxygen to penetrate more easily, and triggers the germination process. Seeds that can benefit from soaking include beans, peas, corn, and some flower seeds. Soaking times vary depending on the seed type, but generally, seeds should be soaked for 4-12 hours in warm water before planting. It is important not to soak the seeds for too long, as this can cause them to rot or lose viability. To soak seeds properly, place the seeds in a container, cover them with tap water, and leave overnight (12 hrs max) After soaking, drain the water and rinse the seeds thoroughly before planting them in the seed-raising mix.
Scarification is a technique used to break or soften the hard outer seed coat, which can prevent germination. Scarification is typically done manually, by scratching or nicking the seed coat using a file, sandpaper, or a sharp knife.
Stratification is a technique used to simulate the natural winter conditions that some seeds require for germination. Stratification involves exposing the seeds to a period of cold and damp conditions, usually around 0-5°C, for several weeks before planting. To stratify seeds properly, place the seeds in a moist medium, such as peat moss, vermiculite, or sand, and store them in a plastic bag or container in the refrigerator for the recommended time. The length of stratification varies depending on the seed type, but generally, seeds should be stratified for 2-3 months. After stratification, remove the seeds from the cold and plant them in the seed-raising mix.
The three main options for seed containers are seed trays, pots, or direct sowing.
Seed trays are convenient for growing multiple seeds in one container and can be used for transplanting seedlings later. Pots are ideal for larger seeds or plants that require more space and can be reused for multiple seasons. Direct sowing involves planting seeds directly in the ground or a larger container and can be useful for plants with delicate roots that do not transplant well. The best container for each plant species depends on factors such as seed size, root depth, and growth habit. In general, smaller seeds require shallower containers and larger seeds require deeper containers. Plants with taproots or longer roots may require deeper containers, while those with shallow roots can do well in shallower containers.
Sowing seeds at the correct depth is important for successful germination and seedling growth. The depth at which seeds should be sown varies depending on the seed size and type. In general, small seeds should be sown shallowly, while larger seeds should be sown deeper. A good rule of thumb is to sow seeds at a depth of two to three times their diameter. Seeds that are sown too shallowly may dry out too quickly or not have enough contact with the seed-raising mix to germinate. Seeds that are sown too deeply may have difficulty breaking through the surface and emerging as seedlings.
Labeling seed containers is important for keeping track of the seed type, sowing date, and other important information.
Watering is an important aspect of seed germination and seedling care. Overwatering can cause the seed-raising mix to become waterlogged and lead to damping-off, a fungal disease that can kill young seedlings. Underwatering can cause the seedlings to dry out and die. To maintain moisture levels, use a spray bottle to mist the seedlings or water from the bottom of the container. It is important not to water the seedlings too much or too often. The frequency of watering depends on factors such as the seed type, container size, and environmental conditions. A good rule of thumb is to water the seed