Though it is commonly propagated by vegetative cuttings, the oleander can also be grown from seed. Oleander (Nerium oleander) is a widely cultivated ornamental shrub commonly seen in both public and private landscaping throughout the southern U.S. states and up the Pacific coastline. Though oleanders can reach upwards of 20 feet tall, most specimens top out at between eight and 12 feet. The plant has large, lance-shaped leaves and produces big, colorful blooms from mid-summer into the fall months.
Growing oleander from seed is not an altogether surefire way to produce a vigorous plant. However, it can be done. Also note that oleander seeds rarely produce a plant identical to the parent.
First, prepare a pot of sterile organic potting soil. Dampen it to a depth of several inches, but do not make it soggy. Place an oleander seed on top of the moist soil and sprinkle a thin layer of soil over the top. Then sprinkle a thin layer of sphagnum moss. Cover the pot with a sheet of plastic film to maintain humidity. Place the pot in the light during the day and maintain its temperature at between 70 and 75 degrees. Maintain the dampness of the potting soil, but do not overwater.
Oleander seed germination is typically erratic under the best of conditions. Seeds may germinate in as few as two weeks. However, it typically takes at least 30 days for germination and may take as long as 90 days. Once the seed begins to germinate, make sure it gets bright light throughout the day. If a growing light is unavailable, a florescent light can be used.
As the seedling grows, carefully modify the lighting intensity and watering schedule to match that which it will receive when transplanted outside. When you have a strong oleander seedling, begin setting it outside for increasingly lengthy periods until it is fully accustomed to the outdoor lighting environment. It can then be transplanted outdoors. As timing is necessarily imprecise with oleander germination, try for a general springtime transplant.