Jack-in-the-pulpit (Arisaema triphyllum) seeds can be sown directly outdoors or started indoors. Harvest the cluster of berries as soon as they turn red in late summer. Each berry usually contains 4 to 6 seeds. Remove the seeds by gently squeezing them from the berries. Seeds can be planted immediately outdoors. Plant seeds ½ inch deep in a moist, shaded location.
Jack-in-the-pulpit seeds can also be started indoors. Before sowing the seeds indoors, the seeds must be stratified (exposed to cool, moist conditions) for 60 to 75 days. Jack-in-the-pulpit seeds can be stratified by placing them in moist sphagnum peat moss or fine sand and then storing them in the refrigerator for 2 to 2½ months. Suitable storage containers include small plastic bags and food storage containers. After the seeds have been stratified, remove the seeds from the sphagnum peat moss or sand. Plant seeds ½ inch deep in a commercial potting mix. In spring, plant the seedlings outdoors.
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