The Japanese morning glory flower, known for its vibrant, trumpet-shaped blooms, is a popular choice for adding vertical beauty to outdoor spaces. Its rapid growth and daily display of color, as each blossom unfurls with the morning light, are widely appreciated.
Understanding the Japanese Morning Glory
The plant commonly referred to as the Japanese morning glory is botanically identified as Ipomoea nil. While it bears the name “Japanese,” this species is not native to Japan but originates from tropical regions of Central America and Mexico. It was introduced to Japan from China during the Heian period, spanning the 8th to 9th centuries. Ipomoea nil is a vigorous annual climbing vine, capable of reaching lengths of up to 5 meters (approximately 16 feet), with stems that twine around available supports.
The leaves of Ipomoea nil are ovate to nearly circular, measuring between 5 to 14 centimeters long, and feature a distinctive heart-shaped base. Its trumpet-shaped flowers unfurl in the morning, closing by the afternoon. Cultivated varieties display a wide array of colors, including blue, purple, pink, rose, and white, often adorned with stripes or contrasting edges. These blooms range from 4 to 6 centimeters (1.57 to 2.36 inches) in diameter.
Cultivating Your Own Plant
Successfully growing Japanese morning glories begins with proper seed preparation due to their hard outer coating. To enhance germination, scarify the seeds by gently nicking or filing their surface, or by rubbing them between pieces of sandpaper. Following scarification, soaking the seeds in warm water for 12 to 24 hours helps soften the tough seed coat, aiding in water absorption and sprout initiation.
The optimal time for planting Japanese morning glory seeds is early to mid-spring, allowing for a long growing season. Starting seeds indoors is recommended, as it provides warm, stable conditions conducive to quick germination. If using grow lights, sow seeds about two weeks before the last expected frost; otherwise, wait until two weeks after the last frost date. Transplant seedlings outdoors only after all danger of frost has passed and night temperatures consistently remain above 10°C (50°F).
Japanese morning glories thrive in full sun, requiring at least six hours of direct sunlight daily for abundant blooming. They prefer well-drained, moderately fertile loam, though they can adapt to various soil types. During germination and early establishment, maintain consistent soil moisture without waterlogging. Given their natural climbing habit, provide a sturdy support structure such as a trellis, fence, or netting early in their growth cycle for the vines to ascend.
Common Care and Troubleshooting
Once established, Japanese morning glories benefit from routine care to promote continuous blooming. Consistent watering is helpful, particularly during dry periods, to keep the soil evenly moist; avoid waterlogging. During the active growing season, applying a balanced fertilizer supports healthy development. When the first flowers emerge, a liquid fertilizer high in potash can be given every 10 to 14 days to encourage more blooms.
Pruning techniques can influence the plant’s shape and flowering potential. Regular trimming helps maintain its form and encourages more blossoms. Pinching back the tips of the vines promotes bushier growth and increased branching. Removing any dead or diseased parts, especially in spring before new growth begins, contributes to overall plant vigor. Deadheading, which involves removing spent flowers, redirects the plant’s energy from seed production back into creating new blooms.
While robust, Japanese morning glories can encounter common garden issues. Pests such as aphids and spider mites can appear, and monitoring plants for early signs allows timely intervention. Powdery mildew can affect foliage, particularly in humid conditions or areas with poor air circulation. Ensuring the plant receives ample sunlight and is grown in well-drained soil helps prevent many common problems.
Cultural Importance
The Japanese morning glory, known as “Asagao” (meaning “morning face”), holds historical and cultural significance in Japan. Introduced from China, it was initially valued for the medicinal properties of its seeds, used as a diuretic and laxative. Over time, its aesthetic appeal grew, leading to its cultivation in the gardens of nobles during the Heian period.
During the Edo period (1603-1868), morning glories became widely popular. Enthusiasts developed countless varieties, showcasing diversity in flower shapes and a wide palette of colors, including pinks, yellows, reds, purples, blues, and whites, often with unique stripes or speckles. This cultivation led to the publication of illustrated books dedicated to these new forms.
The Asagao’s presence extends into various aspects of Japanese culture. It frequently appears in art, poetry, and literature, serving as a symbol of summer’s arrival and the transient nature of beauty and life. The Iriya Morning Glory Market, held annually in Tokyo from July 6th to 8th, celebrates this flower, with thousands of potted plants sold. Growing morning glories is also a common summer assignment for elementary school children across Japan.