Seed Germination and Vegetative Propagation of Seneca Snakeroot (Polygala senega L.) SEED GERMINATION WITH COLD STRATIFICATION 1. In moist sand, cold-stratify (at 3ºC) freshly collected, dried seed for at least 60 days. 2. After stratification, remove seeds and rinse with a weak bleach solution for 1-2 minutes (1 part bleach to 20 parts water). This helps reduce fungal attack. 3. Rinse seeds and soak overnight in water. Remove seeds from water, and wash again in a weak bleach solution for one minute. 4. Using a sharp scalpel or razor blade, carefully slice open the seed coat. Try to remove the lower half of the seed coat. Be very careful not to cut too deeply into the seed. 5. Place seeds on moist filter paper in sealed petri dishes. Place the dishes in a growth chamber or on a warm, south-facing window sill. We recommend adding a commercial fungicide. 6. Allow seeds to germinate, letting the root grow to about 7-10 mm in length (germination rate should be 60-80%). Carefully plant the rooted seedlings into a soil mixture (we use 2 potting soil: 1 peat: 1 sand). Keep the soil moderately moist, and cover the seedlings with a plastic greenhouse lid for the first month to prevent desiccation. Optimal conditions: temperatures of 20-25ºC; 12-14 hours of day length (moderately strong light). Plants appear to do better when grown in constant environment growth chambers for the first month. Seedlings may be lost due to fungal attack and/or desiccation, so watch them carefully! SEED GERMINATION WITHOUT COLD STRATIFICATION The above procedure can also be used on fresh, unstratified seed (i.e. no step 1). However, germination will be low (about 20%). To increase germination, modify step 5 by adding a small amount of the plant hormone gibberellic acid (10-20 mg/l) to the moist filter paper. The germination rate should be 80% or higher. Unfortunately, seeds germinated in this way often produce weak, spindly seedlings. Cold stratification is therefore recommended. SEEDLINGS Seedlings can be grown under lights or outdoors (in trays) for about 4 months. They should then be placed in a cold room to ʻover-winterʼ (3ºC for about 2 months or so). When they are brought back into the light, they will produce a number of side shoots and can be planted outdoors. SHOOT CUTTING Propagation by shoot cuttings is a quick and easy way to produce robust, healthy plants. Shoot cuttings must be taken in very early spring. Harvested shoots should be no longer than 3-5 cm in length, and should consist only of newly developed leaves or (better still) leaf primordia. More fully developed shoots, particularly those in the early flowering stage, will not root well. Shoots should be removed from the base of a healthy plant using a sharp, sterilized razor blade. Treat the cut ends of freshly harvested shoots with a commercial root starter, preferably one with a fungicide. Immediately plant the cuttings into a commercial greenhouse soil (ph-neutral). Water regularly but not excessively, and protect from full sunlight until the root system has a chance to develop (about one month). After a few months, place the cuttings in a cold room to ʻover-winterʼ (or outside, but protected). The next spring, plants will produce multiple (2-5) shoots. DISCLAIMER: These are recommendations only; no guarantee of propagation success is implied.
Mature seneca snakeroot (Polygala senega) plant in flower, photographed in situ (Interlake region, Manitoba, Canada). The coin at center of the plant is a Canadian dollar (2.7 cm diameter).