February's pest plant of the month is blue morning glory
Blue morning glory, Ipomoea indica, may look nice to some, but this smothering and tenacious vine is a real threat to native plants and our gardens. If left, it grows up or over anything in its path. If you learn to recognise it, you’ll see it in many places.
Together we can help stop it spreading through people’s properties and our delicate native bush areas.
Fortunately it doesn’t spread far, not producing seeds in NZ, so it is possible to eliminate it from an area with repeated action. But be careful with the stems and roots as careless disposal is the number one means of it’s spread.
Blue morning glory is also known as blue bindweed, blue convolvulus, morning glory, and it's scientific name is Ipomoea indica. Bindweed is the most descriptive name of theses as the strong and flexible stems will wrap over, under, and around almost anything, strangling other plants. They can damage trees by smothering them and even breaking branches when too heavy.
They do not support our native birds and other wildlife and prevent other plants from growing. So if you care about our birds, you should care about controlling blue morning glory, along side other pest weeds.
What damage does it do?
Climbs over and smothers all other species, ultimately killing them.
Can replace forest and bush with low weedy blanket
Competes with our native plants for light, water, and nutrients
Forms dense blankets which prevent other plants from establishing or growing
What does it look like?
A climbing and scrambling vine, often covering fences and other plants
Stems are tough and hairy
Roots are long an fibrous
Leaves usually have 3 lobes and have silky hairs underneath
Flowering late spring to early winter, it produces large blue-purple trumpet-shaped flowers
Why is it weedy?
Very fast growth rate
Lives a long time
Forms dense, smothering blanket
Ability to climb to top of high canopy, threatening even our largest trees
Dominates vegetation where it occurs, particularly along the edges of reserves, parks, roadside and gardens
Tolerates a variety of conditions
How does it spread?
Creeping and climbing stems spread this plant locally
Stem and root fragments are moved in dumped vegetation or soil
Note: if you clear blue morning glory from your garden or elsewhere, please dispose of the stems and roots carefully (see below or get in touch for more info).
Thankfully little or no seed is produced in New Zealand, so it only spreads far when people move parts of the plant for disposal.
Slideshow of blue morning glory photos:
What can you do about it?
Spread the word
Talk to your friends, whanau and neighbours about the threat from pest plants, show them this article, or tell them that Pest Free Kaipātiki have advice and resources to help.
Tell them about the PFK Community Toolshed where they can borrow equipment and tools to help tackle pest plants.
Tackling weeds like blue morning glory will help to support our native birds and other wildlife.
Getting rid of blue morning glory
Firstly, check that the species is not a valued native plant - there are some species that can look similar. If you are unsure, check on iNaturalist or WeedBusters, or send us photos, both close up and wide shots.
Pull or dig up roots - check and remove even small fragments
Cut stems can be pasted on the cut end and along the scrapped stem with herbicide gel (see details below)
Dispose of roots and stems carefully! - Humans are the number 1 cause of this weeds spread.
Follow up in 2 to 3 months time, as this weed will grow back in places.
As this weed is persistent it may look like you're losing the battle - but don't be put off! The lack of seeds means this vine can be eliminated permanently from your property with repeated control by hand or herbicides.
Pull up or dig out the roots - repeat this a few times a year, ideally every 3 months, and more often during the summer
Ensure stems are not in contact with the ground or they will regrow
Collect and dispose of any stems and roots which are on the ground
Cut and paste herbicide control
Cut stems close to the ground and paste the cut end and a length of the scrapped stem with a thin smear of herbicide gel*, such as MetGel* (metsulfuron)
You can leave the main stems to wither and die off if not in contact with the ground.
Follow up in three months for vines missed.
Spot spraying herbicide control
if you are comfortable with spot-spraying herbicides*, email us for more info
cut the vines at around knee height and leave the tops to die off. Allow a month or more for the in-ground end to re-sprout green leaves. At this point, carefully spot spray without damaging surrounding native plants with 0.5g per litre of metsulfuron* (not close to water ways or valued plants). Repeat until eradicated roughly every 3 months.
*Safety - read the points below
Caution: Always read the labels when using herbicides and wear appropriate protective equipment where necessary.
Metgel and metsulfuron - Be very careful applying metsulfuron or Metgel near water bodies and near valued plants - only apply a very thin smear of gel on cut stems/trunks and do not allow the herbicide to drip on to other surfaces or soil.
Do not pull down vines if they are smothering other plants. This can damage the plants and pull down branches on yourself. Better to cut the stems closer to ground and allow the above ground stems to die and whither.
Only need to dispose of roots and stems
Keep them off the soil until they dry out and die
Dispose of at a refuse transfer station
Borrow a weed bag from our community toolshed for free, and let the stems and roots rot down inside it for a few months
See all our pest plant disposal information on our website.
What can you plant instead?
If you have blue morning glory on your property, please consider getting rid of it over time and planting native plants to replace it.
Good alternatives are the following, which all help native wildlife:
NZ bindweed Calystegia tuguriorum
Scrambling fuchsia (Fuchsia perscandens)
Leafless clematis (Clematis afoliata)
Check out these pages for lots more photos:
See section 20 of the Plant me instead booklet
How can you help restore Kaipātiki?
Recognise - Learn what pest plants and native plants look like
Report - Report locations where pest plants are damaging native plants or entering native bush
Remove - Find out how to control pest plant and get supplies from our Community Toolshed
Restore - Plant natives to stop pest plants coming back and to support our native wildlife.
If you have an area of pest plants threatening an area of bush or reserve near you, get in touch and we can help.
Find more information about pest plants on our other pages: