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Seed Germination Tips
Tree seeds are particular in the way they break dormancy. Most are dried to below 10% moisture for storing, but seed at 10% will rarely germinate, therefore the seeds require a "stratification period" to force the seed into growth. There are two types of stratification: cold (best done at 34-41 degrees F) and warm (best at 68-86 degress F). Some seeds require one or the other - some require both. When both are required, warm stratification is performed first. Some seeds are very fine and should be sown "under glass", as detailed below.
Natural stratification is achieved by planting the seed in a prepared bed outdoors in late fall, where rain, snow and freezing temperatures will allow the seed to germinate. Artificial stratification is done for convenience. We have discovered the following methods of artificial stratification work best:
Warm stratification is required to soften hard seed coats and to allow the embryo to mature. Embryos must be mature to germinate and they must be moist to mature. Warm stratification is achieved by soaking seed in warm water for 8-24 hours. Extremely hard seeds such as hickory may be "scarified" or nicked, but care must be taken not to damage the embryo. A better method is the hot water treatment.
Cover the seed with boiling water and allow to stand for 12-24 hours. IF any seed is floating in the water at the end of this time, repeat the process. Those that have sunk or swollen may be planted.
Drain the water from the seed. Take a handful of sphagnum peat, vermiculite or other sterile moisture medium and place it in a zipperlock plastic bag. (Sphagnum peat is best for warm stratification as it contains anti-fungal properties.) Add enough water to thoroughly moisten the seed and allow it to rest for a couple of hours. Hold the bag upside down and squeeze out any excess water. Add the seed to the bag and shake to mix. The temperature should remain between about 68 and 86 degrees F.
Check the bag about once a week. If you notice any mold forming inside the bag, remove the molded seed and throw them away. If the moisture mix appears to be dry, add enough water to moisten it and squeeze out any excess water, then re-seal the bag. Check the next day to make certain that no water is standing in the bag. If so, pour it out
If your seed requires less than 30 days cold stratification, you may simply place the seed in a refrigerator for the required time period. If it requires more than 30 days, moist stratification is best and the process is the same as for warm stratification, but at 34-41 degrees F. Soak the seed for 24 hours in warm water. Drain the water. Get a handful of sphagnum peat, vermiculite or other sterile moisture medium and place it in a zipperlock plastic bag. (Sphagnum peat is best for warm stratification as it contains anti-fungal properties.) Add enough water to thoroughly moisten the seed and allow it to rest for a couple of hours. Hold the bag upside down and squeeze out any excess water. Add the seed to the bag and shake to mix. Place the bag in a refigerator. An unheated outbuilding or garage will work as long as the temperature does not exceed 41 degrees F.
Check the bag about once a week. If you notice any mold forming inside the bag, remove the molded seed and throw them away. If the moisture mix appears to be dry, add enough water to moisten it and squeeze out any excess water, then re-seal the bag. Check the next day to make certain that no water is standing in the bag. If so, pour it out. If you notice any seeds sprouting, remove them and plant them.
Most tree seeds require the recommended treatments only once. Do not cold stratify a seed and then fall sow. Once the initial stratification is complete the seed is ready to germinate. If the outdoor temperature warms, the seed will germinate and then may be killed by the freezing temperatures of winter. In addition, once the seed has completed stratification, it is ready to start growing. In this state the seed will use up its energy reserves at a rapid rate and will have a much reduced shelf life at warmer or cooler temperatures.
SOWING UNDER GLASS
This method of sowing seeds is the best to use with very tiny dustlike seeds like Kalmia.
Take a flat or pot and fill it 3/4 full of moistened sterile planting medium (commericial seed starting mixes are fine, or you may make your own using a mix of 1 part sphagnum peat to 1 part sterile sand). Sow the seed on the surface evenly, making certain not to sow too densely. Place the flat inside a clear plastic bag and seal it shut with a twist tie.
Place the flat in a sunny room or greenhouse where the temperature reaches at least 68 degrees F during the day and drops slightly at night. (Don't place in direct sunlight.) Keep the flat moist, but not soggy. Water from the bottom by pouring water into the plastic bag. Remove any water not soaked up in an hour. Germination usually takes place from 2-4 weeks, but may take longer depending on the variety of seed. After germination, acclimate the seedlings to the room temperature over a 2-3 week period by misting the seedlings. Remember that once this process begins, you will have to water more frequently.
Handling Bareroot Seedlings
Bareroot seedlings should be planted as soon as they arrive, but if this is not possible, you may handle them as follows:
If at all possible, leave the plants in the box and packing in which they arrived, just making certain that the material around the roots has not dried out and that the tops of the plants are dry. Keep the box in a cool place, around 33-38F or store in a cool location, such as a basement or cellar. Do not store near fresh produce or cut flowers as these produce ethylene gas, which is toxic to live plants.
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