New Zealand Garden Swap Newsletter
Garden Swap Website - Newsletter Cover - Page 5 - Page 7Stratification & Scarification
ScarificationThe key to the germination process is for water to reach the interior of the seed. If the temperature is right (usually 75 degrees F) and the seed is receiving some air, the water will "wake up" enzymes that begin to convert stored carbohydrates into sugars that can be used by the embryo for growth. Some seeds have extremely hard seed coats which make water penetration extremely difficult. Many people will pour near boiling water over these seeds and let them soak overnight before sowing (a dripping faucet over seeds in a cloth or paper towel is preferred to allow for some exposure to air). For best results with these particular seeds, it may be necessary to nick the seed coat in order to allow the water to penetrate into the interior. For small to medium seeds, you can simply rub them against sandpaper which will grind down the coat. With larger seeds, you may need to use a knife or a hacksaw - be careful! You do not need to make a very large hole at all - a tiny nick will do the job just fine. In nature, the water usually enters the seed through a tiny opening called the micropyle which is located right next to where the seed was attached to the parent. Some common plants that typically benefit from scarification include cannas, pad cacti and many palm varieties. There is a great advantage to most hard seed coats - they typically have an extremely long shelf life |
StratificationStratification is the process of exposing seeds to a cold, moist environment for several weeks before planting. This treatment is used on seeds that require a period of cold in order to germinate well. Some plants produce seeds that refuse to germinate until they are exposed to a period of cold temperatures. This is a protective mechanism that allows tiny seedlings a whole growing season in order to get big enough to withstand a cold winter. Without this mechanism, seeds from these plants would germinate in the fall and the tiny seedlings would be at the mercy of a long winter. A spring rising is a much more advantageous strategy for these varieties. To fool these seeds into thinking it is time to wake up, place the seeds in a plastic bag with some moistened seed starting mix and leave them in your refrigerator for two to three weeks. Make sure to open the bag a few times during that period to ensure that the seeds have some contact with air. If the seeds still do not sprout well after the suggested number of days, repeat the procedure with the entire seed tray. |
