Annual morning glory (Ipomoea spp.) is a quick-growing flowering vine that thrives in warm sunny spots. Their large flowers open in the morning to the delight of the early bird gardener. But just mentioning the name “morning glory” can cause concern among some. If you’ve lived in warmer areas of the United States, you might know annual morning glory as a nuisance weed. And the hard-to-manage weeds called bindweed (Convolvulus arvensis) and hedge bindweed (Calystegia sepium) share the common name of “morning glory,” but are very different plants.
One of the most noticeable differences between bindweed and annual morning glory is their growth habits. Both are vines with trumpet-shaped flowers but behave very differently in the garden. Bindweeds are perennial and spread through underground roots (up to 9 feet deep!). It can grow in a variety of soil types and is often found in fields, gardens and along roadsides. Bindweed plants tend to grow along the ground or in low-lying plants like vegetables, grass, herbs, and shrubs. Bindweed can be incredibly difficult to manage.
Here in Oregon, annual morning glory plants won’t survive a frost, and vine growth is limited by the shorter growing season. Annual morning glory grows from seed and the plants may self-sow. This means that seeds produced by the previous year’s plant will sprout and regrow in the same place. The seeds can survive in the soil for several decades so may show up in the same area for years. Luckily, unwanted seedlings are easy to control by hand-pulling.
The leaves and flowers of the two plants are also different. Bindweed leaves are arrow-shaped and smaller than the leaves of annual morning glory (see photo). Annual morning glory leaves are large and heart-shaped. Bindweed flowers are white or pink and about 1 inch across.
Annual morning glory flowers are larger (2-6 inches across depending on the cultivar). The flowers come in various colors, from blue to red and purple to pink and white. Annual morning glory blooms from early summer until the first frost.
With their vibrant flowers and lush foliage, beach morning glories are a popular choice for coastal gardens. However, these plants are prone to downy mildew, a fungal disease that can quickly devastate your beach morning glories if left unchecked. Identifying and treating downy mildew promptly is key to saving your plants.
Recognizing Downy Mildew
Carefully inspect plants regularly to spot downy mildew early before extensive damage occurs. Signs include:
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Yellow splotches on upper leaf surfaces
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Gray, fuzzy growth on undersides of leaves
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Curled, distorted, or stunted leaves
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Premature leaf drop
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Poor flowering
Downy mildew thrives in cool humid conditions. Pay extra attention after periods of rain, mist, fog or heavy morning dews.
Improving Air Circulation
Downy mildew fungi thrive in stagnant, humid air. Improve airflow by spacing plants 1-2 feet apart and thinning inner branches. Avoid planting in dense shade. For potted plants, reposition containers to maximize air movement between them.
Watering at the Base
When watering from overhead, moisture lingers on leaves, creating optimal conditions for downy mildew Instead, water at the soil line with soaker hoses or drip irrigation This keeps foliage dry. For containers, water into the soil only.
Applying Fungicides
For serious downy mildew infections, fungicides are often needed to eradicate the pathogen. Use fungicides labeled for edible plants and follow all safety directions. Apply to tops and bottoms of leaves. Repeat applications per product instructions until downy mildew is under control.
Removing Infected Leaves
Prune off leaves showing clear symptoms of downy mildew. Make cuts at least 6 inches below visible disease to ensure removal of all infected tissue. Bag up clippings and discard – do not compost. Sterilize pruners between each cut with isopropyl alcohol. Removing infected leaves helps slow disease spread.
Harvesting Promptly
Pick fruits, vegetables, and flowers promptly when ready for harvest. Overripe produce and spent blooms are highly susceptible to downy mildew infection and can fuel rapid disease progression. Removing mature plant material limits available hosts for the pathogen.
Solarizing Soil
Solarization uses radiant heat from the sun to pasteurize soil and kill fungal spores, providing preventive control. Moisten soil, cover with clear plastic, and leave in hot sun 4-6 weeks. Replace spent plants with resistant varieties when replanting treated areas.
Growing Downy Mildew-Resistant Varieties
Select beach morning glory varieties labeled “DMR” indicating resistance to downy mildew. Resistant cultivars possess genetic traits that impede pathogen growth and infection. Combine resistant plants with other cultural controls for most effective protection.
Monitoring Moisture
Excess moisture stresses plants, increasing vulnerability to fungal and mildew diseases. Allow soil to partially dry between waterings and avoid wetting foliage. Use drip irrigation and mulch to maintain even moisture levels. Promptly adjust any leaky valves or sprinklers.
Using Organic Fungicides
Organic fungicides containing neem oil, Bacillus subtilis, potassium bicarbonate, or citric acid can help combat downy mildew without synthetic chemicals. Coat leaf tops and bottoms thoroughly and reapply weekly per product instructions. Rotate between different natural fungicides for best results.
Controlling Weeds
Weeds serve as hosts for downy mildew fungi. Remove weeds in and around planting beds either by handpulling or using organic herbicides. This eliminates alternate infection sites and discourages disease carryover between seasons. Maintain a weed-free area around plants.
With prompt action at the first signs of infection, you can protect your beach morning glories from devastating downy mildew damage. Consistent monitoring, cultural controls, and targeted organic treatments will help keep plants healthy and blooming strong.
How to grow annual morning glory:
- Choose a site that receives full sun and has well-draining soil. Annual morning glory also grows well in containers.
- Make sure there is a trellis or fence for the plants to climb. Annual morning glory vines can grow up to 15 feet long depending on the cultivar.
- Annual morning glory is a heat-loving plant, so wait until the soil warms up to at least 60 F. Then, plant the seeds directly in the soil about ¼” deep. Keep the soil moist.
- Once past the seedling stage, the plants tolerate dry soil but appreciate irrigation during heat waves.
Cultivars of annual morning glory to try:
- Heavenly Blue (4- to 5-inch blue flowers)
- Scarlett O’Hara (4-inch red flowers)
- Flying Saucers (5- to 6-inch variegated blue and white flowers)
- Grandpa Ott’s (2- to 3-inch deep purple flowers with a red center)
- Zeeland Hybrid (mix of pink, purple, white, and variegated flowers)
Want to learn more about this topic? Explore more resources from OSU Extension:
A vine of field bindweed with arrow-shaped leaves compared to the large heart shape leaves of Annual Morning Glory. Credit: Brooke Edmunds, Oregon State University
Annual morning glory flowers come in various colors included variegated (multi-colored). Credit: Brooke Edmunds, Oregon State University
Annual Morning Glory is a vining plant and requires a fence or trellis to grow on. Credit: Brooke Edmunds, Oregon State University
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