How to Grow Morning Glory in Australia

Morning glory (Ipomoea nil), also called Japanese morning glory, is a twining climber in the bindweed family, Convolvulaceae. It is grown as a warm-season annual for its trumpet flowers. The Mixed Colours vine climbs 1.5 to 3 m in a season and opens fresh 5 cm blooms each morning. Many failures happen before the first leaf, when hard seed goes untreated into cool soil and simply sits there.

Three mistakes that matter

1. Sowing hard seed into cool soil. The tough seed coat keeps water out, and untreated seed in cool, damp soil can lie idle for weeks or rot. Soak or nick it first, as set out in Sowing Seeds, and wait for the soil temperature in When to plant.
2. Feeding it like a vegetable. Rich, heavily manured soil and nitrogen-rich feeds give a wall of leaves and few flowers. Dig in compost only, keep later feeds light, and switch to potassium once buds show, as in Care by growth stage.
3. Letting every flower set seed. A vine left alone drops seed that can survive in the soil for decades. Deadhead as described in Pruning and Training, and pull unwanted seedlings while small.

When to plant

Morning glory is frost tender. Sow once frosts are over and the soil holds at least 18°C; seed germinates best at 21 to 28°C. One sowing usually flowers until frost or cold autumn nights stop it, so there is no need to sow in batches.

At the cool edge of a window, start seed in pots under cover three to four weeks before planting out. Late sowings still flower, for a shorter season.

Site, soil and setup

Give the vine full sun, at least six hours a day, and shelter from strong, drying wind. It grows in most well-drained soils from acid to neutral, and moderately fertile ground suits it better than rich ground.

A flowering vine needs no strict rotation; clearing the old vine each autumn, as in Pruning and Training, is enough.

Is it a weed where you live?

No state or territory declares Ipomoea nil a weed, but councils keep their own local lists. Check with yours before planting near bushland or a creek.

Blue morning glory (Ipomoea indica), sometimes called dunny creeper, is a different plant. It is a long-lived climber that spreads from rooting stems, an environmental weed in several states and listed as pest vegetation by Brisbane City Council. Do not plant it. Its flowers are larger, 7 to 10 cm across, come in clusters of two to twelve, and rarely set seed pods in Australia.

Container growing

Use a pot of at least 20 L, about 30 cm wide and deep, with drainage holes and fresh potting mix. Fix a trellis or obelisk at least 1.5 m tall in the pot at sowing, and sow two or three seeds around its base.

• Watering: pots dry out fast in summer, so check them daily and water whenever the top 2 cm feels dry.
• Feeding: water in seaweed solution at 30 mL per 9 L every fortnight. From the first flowers, switch to liquid potash at the label rate, fortnightly.
• Position: a sunny balcony railing makes a ready-made support.

Sowing Seeds

Preparing the seed

Seed of this species can take four weeks to four months to come up unless the coat is softened first. Soak the seed overnight in lukewarm water and sow any that have swollen straight away. Nick the coat of those that stay hard with nail clippers, or rub one side on sandpaper, then soak them again. Soaking and scarification explains why.

Sowing direct

• Sow seed 12 to 15 mm deep, two to a spot, with spots 30 cm apart and about 15 cm out from the support.
• Keep the soil damp but never soggy; seedlings usually appear in 7 to 21 days.
• Thin to the stronger seedling at each spot once true leaves show.
• Spread a light mulch once seedlings stand about 5 cm tall, keeping it clear of the stems.

Starting under cover

• Sow one treated seed per small pot of seed raising mix, 12 to 15 mm deep.
• Keep pots warm and bright; a seedling heat mat helps hold the soil at the temperature given in When to plant.
• Sow three to four weeks before planting out, so roots do not fill the pot.
• Harden off seedlings over one to two weeks first (moving them outdoors for longer each day so they adjust to sun and wind).
• Plant each seedling at the depth it grew in the pot, beside the support, and water it in.

Care by growth stage

Sun, steady water and a lean diet decide how freely morning glory flowers. Weeks count from sowing.

If growth stalls in very poor soil, a light dose of all-purpose controlled release granular (NPK around 14-5-10) scratched into the soil can help.

Pruning and Training

The vine twines unaided, so training is mostly steering, and pruning controls size and seed.

• Guide the tips: when vines reach about 15 cm, wind each tip onto the support in the direction it already turns.
• Spread the cover: tie wayward stems loosely across the trellis so the vine covers the whole screen.
• Trim for size: cut back stems that reach gutters, window frames or neighbouring shrubs, as often as needed.
• Remove faded flowers: pinch off spent blooms before pods swell, which limits self-sowing and can keep new flowers coming.
• End of season: once frost blackens the vine or flowering stops, pull it out and bin any stems carrying pods.

Companion planting

The best partners either take turns on the same support or bring in the insects that eat aphids.

Grows well with

• Sweet pea: a cool-season climber that finishes in spring, just as morning glory goes in on the same trellis.
• Sweet alyssum (Lobularia maritima) at the base: its small open flowers feed hoverflies, whose larvae eat aphids.

Keep apart

• Sweet potato: a close relative, and convolvulus hawk moth caterpillars feed on both.
• Vegetable beds and young shrubs: the vine twines over anything within reach and can smother it.

Harvesting Blooms

Each flower opens in the early morning and closes by afternoon, so enjoy morning glory on the vine rather than in a vase.

• For the table, float a freshly opened bloom in a shallow bowl of water; it lasts about a day.
• To save seed, leave a few late flowers and let the pods dry on the vine until they turn papery and straw coloured.
• Pick dry pods before they split and rub them open over a tray; each holds four to six black seeds.

Dry saved seed indoors for a week or two. Store it in a labelled paper envelope inside a sealed jar in a cool, dark cupboard. Kept dry, hard-coated seed stays viable for years. No part of the plant is edible.

Common problems

Leaves but no flowers. Beyond the rich feeding covered in Three mistakes, shade and heavy watering both push leafy growth at the expense of buds.

Seedlings collapse at soil level. Damping off (Pythium species and Rhizoctonia solani) rots young stems, most often in cold, wet seed raising mix or soil. Read more

Vine yellows and wilts in wet ground. Waterlogged soil rots the roots, so the vine droops even though the soil is wet.

Pests and diseases

Morning glory has few serious pests, and the worst of them arrive in hot, dry spells.

Aphids (family Aphididae). These small sap-suckers cluster on shoot tips and buds, leaving new growth distorted and sticky with honeydew. Read more

Two-spotted mite (Tetranychus urticae). Tiny mites speckle leaves pale and spin fine webbing underneath, and numbers climb fast in hot, dry, dusty weather. Read more

Convolvulus hawk moth (Agrius convolvuli). Its caterpillars eat the leaves of bindweed-family plants and grow up to 9 cm long, green with a tail horn at first. Pick them off by hand.

Prevention first

• Keep vines watered through heatwaves, because drought-stressed plants suffer worst from mites.
• Hose shoot tips and leaf undersides with a firm jet every few days in hot weather.
• Check under the leaves weekly, where mites and young caterpillars hide.
• Avoid broad-spectrum sprays, which kill the ladybirds and lacewings that eat aphids.

Tips

1. Grow a vine over a hot west-facing window or wall to shade the glass or brick through summer. In frosty areas it dies back in time to let winter sun through.
2. Morning glory is a short-day plant, cued to flower by long nights. Older vines need less darkness, which is why they still flower through the long days of summer.
3. Do not mistake field bindweed (Convolvulus arvensis) for a self-sown vine. It has smaller, arrow-shaped leaves and white or pink flowers about 2.5 cm across, and it spreads from deep perennial roots.