Invasive morning glory: how to control it?

Ipomoea, a prized climbing or creeping plant

Sown mid-May in open ground, morning glory is a spectacular ornamental plant, ideal for quickly covering a wall or pergola, providing shade or hiding an unsightly area. It finds its place in wild gardens, flowering fences, or even in a pot on a terrace.

Its rapid growth also makes it an excellent temporary groundcover or a seasonal vegetative screen, in areas where it does not survive winter. It is a natural, low-cost and decorative solution to beautify a fallow area or structure a corner of the garden while waiting for more permanent plantings.

However, it can sometimes become invasive…

Morning glory is grown as a climbing plant or a creeping plant

Ipomoea, a plant of a family renowned for its vigour

Term “ipomoea” actually covers several hundred plant species belonging to genus Ipomoea, family Convolvulaceae. Widespread in tropical and subtropical regions, these herbaceous plants can be annual or perennial in areas with mild winters, and climbing or creeping. Among best-known garden species are Ipomoea purpurea, Ipomoea tricolor, Ipomoea lobata or Ipomoea indica or learii, the latter being particularly feared for invasive habit.

Convolvulaceae also include other plants known for vigour and ability to colonise space rapidly, to point of becoming undesirable in some contexts. This is notably case of field bindweed (Convolvulus arvensis), an adventive well known to gardeners, very difficult to eradicate once established because of long running roots. This perennial plant twines around crops and ornamental perennial plants, slowing growth and making weeding laborious. Its cousin, hedge bindweed (Calystegia sepium), behaves similarly.

Three highly invasive Convolvulaceae species: clockwise from top, Indian morning glory (Ipomoea indica or learii), hedge bindweed and field bindweed.

As for Ipomoea batatas, better known as sweet potato, it is indeed part of genus Ipomoea, but displays very different behaviour from ornamental ipomoeas. This tuberous perennial plant, generally grown as annual in our latitudes due to frost sensitivity and rapid growth, is not considered invasive. Indeed, it is frost-tender, does not self-seed and multiplies by tubers.

Ipomoea batatas does not display same invasive behaviour

Why can Ipomoea become invasive?

The vigour that gives Ipomoea its charm can also become a nuisance in the garden. Its twining stems coil around any available support: wire mesh, stakes, shrubs, even neighbouring plants. When it thrives, it can smother less vigorous plants or hinder their development by shading them.

Some species are particularly persistent. This is the case of Ipomoea indica, native to South America and capable of multiplying by natural layering, by rooting its stems where they touch the soil. In mild climates, although considered an annual, it remains in growth all year round and can quickly form a dense carpet that is hard to remove. It can also escape gardens to colonise natural habitats, notably fallow land, embankments and hedgerows, impacting local biodiversity. Its vigorous rooting makes it difficult to dislodge once established.

Other species, such as Ipomoea purpurea and Ipomoea tricolor, are less problematic in temperate climates because they do not survive frost. However, they self-seed abundantly if their capsules are allowed to ripen, and can reappear in large numbers the following year, sometimes well beyond the areas originally sown.

Ipomoea purpurea and tricolor are significantly less invasive

What precautions should be taken to prevent proliferation?

It is perfectly possible to enjoy the beauty of morning glories without letting them take over, provided a few simple cultivation rules are followed.

First, it’s better to choose less invasive species, such as Ipomoea purpurea, which has a limited lifespan, or sterile horticultural varieties that produce few or no seeds.

Growing them in pots is also a good solution to limit their root expansion. Planting them in large containers or tubs prevents them taking over borders or garden soil. It also makes their development easier to control and allows simple removal if necessary.

It is also advisable to cut off faded flowers before seeds form, especially at season end. This tidy-up prevents self-seeding and limits unwanted spread.

Spent flowers of morning glories should be cut off before seeds form.

Finally, it is recommended to check surrounding areas regularly: any layered stem or unwanted seedling should be removed quickly while the plant is still young and easy to eliminate.

What to do if morning glory has already colonised the garden?

If an ipomoea has become too vigorous, escaped your control and started to colonise an area of the garden, the best strategy remains systematic hand-pulling, to be repeated several times during the season. Make sure to remove roots or rooted stems thoroughly, as these can give rise to new shoots.

In some cases, covering the soil with heavy-duty sheeting for several weeks can help weaken underground parts. Chemical treatments should be avoided, not only because they do not always guarantee complete eradication but also because they damage soil balance.

Be persistent: a well-established ipomoea can take two to three seasons to disappear completely, especially if it spreads by layering. Regular monitoring remains essential, even after large-scale removal.