Late summer through early fall is a favorite time of year for many northeast gardeners, including myself. Much of the vegetable harvest has been collected, asters and goldenrods dot the fields and byways, and moonflowers and morning glories are at their peak.
Morning glory is the common name for a large number of flowering plants in the Convolvulaceae family. In the northeast we grow several species as beautiful cultivated annuals. Most members of the morning glory family are from the warmer regions of the world and are killed by frost. Of course the one species that is hardy, bindweed, is an invasive weed and is very difficult to eradicate.
Probably the most well-known morning glory is Ipomoea tricolor ‘Heavenly Blue’. I have never seen a more perfect blue flower. It is that same azure blue that one sees looking up to the sky on a sunny, clear September day. The sky blue blossoms have a creamy white center and reach up to 5 inches across. The attractive, heart-shaped leaves are occasionally nibbled on by tortoise beetles but otherwise are pretty much left alone.
‘Heavenly Blue’ was my standard for a number of years until I was introduced to ‘Blue Star’ by a fellow garden club member. This cultivar also has large flowers but they are a dreamy pale blue with a darker blue star on the interior of the blossom. Quite striking and a bit different. Last year I planted pale yellow snapdragons and white sweet alyssum at its feet for a rewarding show from midsummer until the morning glories were hit by a frost.
I thought I had picked up a ‘Heavenly Blue’ morning glory plant last June at a plant sale. It was a seedling with only the cotyledon leaves unfurled and a tag that said blue morning glory. So it was planted next to the pergola, watered and to be honest, forgotten about. When I finally got back to that bed to do some weeding and mulching, I noticed the morning glory had 3-lobed not heart-shaped leaves and smaller bluish flowers. The stems were hairy and the plants stopped blooming in August. Maybe they would have continued if they were watered more regularly. It looks like this plant is the ivy-leaved morning glory, I. hederacea. I saved some seeds and will probably grow it next year.
In a large container filled with the scarlet and gold gloriosa lilies I always plant a few saved seeds of the cypress vine, I. quamoclit, for the hummingbirds. These plants quickly germinate and scramble up the obelisk. By the end of the summer they are clambering up the drainpipe and heading for the roof. Bright red tubular flowers are pentagonal in shape when viewed from the front. The leaves are finely dissected.
Another favorite morning glory which I did not get around to planting this year is the moon flower, I. alba. While morning glories open during the day and close with the setting sun, moon flowers do just the opposite. Huge white fragrant flowers unfold as the sky dims. They stay open all night to be pollinated by moths and close as the sun arises. Flowering is brought on by a summer short day photoperiod which means that there are approximately 12 hours of light and darkness each day which is from late summer into early fall, in other words right now. Someone the next town over planted a picket fence thick with moon flowers and I purposely drive by it as often as I can. The moon flower is also an heirloom plant. The buds open over the course of several minutes so you can just stand there and watch this amazing show.
We don’t often think of vegetables being related to flowers but sweet potatoes are also in the genus Ipomoea. I tried growing sweet potatoes a number of times. At first, it was a fairly successful endeavor and then, the voles found the plants. Last time I tried, I only got a small basketful of unchewed roots. The voles have not bothered the sweet potato vines that are sold and grown as foliage plants. (This could be because I keep them in containers off the ground!)
Sweet potato vines do not climb but just tend to cascade or sprawl so are a great choice for containers or hanging baskets. The colors of this foliage plant are great for pairing up with either contrasting or complementary plantings. The dark purple leaves of ‘Blackie’ look fantastic with coral verbena and silver dusty miller. Chartreuse ‘Margarita’ mixes it up nicely with blue salvia and yellow marguerites and green, pink and cream ‘Tricolor’ looks great with pink petunias.
Except for sweet potato vines which are typically purchased as plants, the other morning glories mentioned are all grown from seed. The seeds are poisonous and have a hard seed coat. While I have seen some sources suggest nicking the seed before planting, I find it is easier to just soak them overnight (or if you forget – for two nights) and then plant them. The seeds need warm soil temperatures to germinate so they do not usually get planted in New England until around Memorial Day weekend. Since many species and cultivars need 75 to 110 growing days before they blossom, you might want to start the seeds indoors 4 to 6 weeks before you can set them out.
If you do decide to start seeds indoors, give the seedlings something to grasp hold of. Morning glories have a curious way of climbing. This is a great video of young vines twisting and reaching out for that strong support: https://www.youtube.com/watch?v=dTljaIVseTc
This type of response when the vine encounters something it can wrap its stem around and then proceeds to do so, is called thigmotropism. It is movement of a plant in the direction of touch. The plant ‘feels’ an object in its path that it can use for support and the rubbing against this object causes the stem to curl around it. Whether the vine goes right to left or left to right seems to be predetermined by its genes.
Because morning glory flowers only last a day, the Victorians felt it symbolized love and affection as well as mortality. In modern times, the morning glory represents the eleventh year of marriage and the month of September – how appropriate.
Good gardening to you!