Fertilising guide
How to fertilise Ipomoea purpurea (Ipomoea purpurea)— schedule & NPK
Also called common morning glory, purple morning glory, tall morning glory.
More about ipomoea purpurea
About Ipomoea purpurea
Ipomoea purpurea · also called common morning glory, purple morning glory · flowering
Common morning glory is a fast-growing annual twining vine from tropical America, grown for its abundant funnel-shaped flowers in purple, blue, pink, and white that open at dawn and fade by afternoon. Easy from seed, it climbs by twining stems and heart-shaped leaves to clothe a trellis in a single season, then dies with the first frost.
Growth habit: Vigorous herbaceous annual climber that twines counter-clockwise around supports; can self-seed prolifically and become weedy in mild climates.
Watch for — All leaves, few flowers: Caused by too-rich soil or excess nitrogen fertiliser. Stop feeding nitrogen and ensure full sun to trigger blooming.
What fertiliser ipomoea purpurea actually wants — and why
Ipomoea purpurea is a heavy-blooming flower with a big appetite — a regular high-potash feed through the season is what drives a long, dense display.
A high-potassium ("high-potash") flowering feed — tomato-style or a dedicated bloom/rose feed. Potassium powers flowering; a high-nitrogen feed gives you a leafy plant with disappointing bloom.
For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for ipomoea purpurea: match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.
How often to feed ipomoea purpurea, and which months
Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For ipomoea purpurea:
Feed sparingly. Too much nitrogen produces lush vines and few flowers. A single application of a low-nitrogen, high-phosphorus feed at planting, or a light monthly high-potash feed, supports blooming without runaway growth. For a hungry bloomer that means feeding regularly — monthly — right through flowering across the main season (spring through early autumn), tapering as blooming ends.
The dormant-season rule matters more than the exact interval: skip feeding entirely when ipomoea purpurea is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.
What strength to mix for ipomoea purpurea
Follow the flowering-feed label rate for ipomoea purpurea, or half strength if feeding very frequently. These plants genuinely use the nutrients — under-feeding shows up fast as a thin display.
Feeding always goes onto already-damp soil, never dry roots — water ipomoea purpurea first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the ipomoea purpurea watering schedule.
Signs you are over-feeding ipomoea purpurea
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for ipomoea purpurea:
- Lots of lush leaves but few flowers (too much nitrogen).
- Scorched leaf edges and salt crust from too-strong or too-frequent feeds.
- Soft, sappy growth prone to aphids and mildew.
Signs you are under-feeding ipomoea purpurea
- Sparse, small, short-lived flowers and pale foliage.
- A tired plant that stops blooming early in the season.
- Weak growth and poor repeat-flowering after the first flush.
If the symptoms point at watering, light or roots rather than nutrition, the full ipomoea purpurea care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Container-grown ipomoea purpurea accumulates feed salts fast with frequent feeding — water until it drains each time and flush pots with plain water every few weeks to prevent scorch.
Organic vs synthetic feeds for ipomoea purpurea
Organic options
A liquid comfrey or seaweed feed (naturally potassium-rich) plus compost or well-rotted manure as a mulch. UK: comfrey feed, organic Tomorite, or rose feed; US: Espoma Rose-tone or Neptune's Harvest. Feeds and improves soil.
Synthetic / liquid feeds
A high-potash flowering feed on a regular cadence — UK: Tomorite (Levington), Phostrogen or a specialist rose feed; US: Miracle-Gro Bloom Booster or a rose food. Fast, reliable bloom response.
Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.
Fertilising ipomoea purpurea — frequently asked questions
What fertiliser does ipomoea purpurea need?
A high-potassium ("high-potash") flowering feed — tomato-style or a dedicated bloom/rose feed. Potassium powers flowering; a high-nitrogen feed gives you a leafy plant with disappointing bloom. Ipomoea purpurea is a heavy-blooming flower with a big appetite — a regular high-potash feed through the season is what drives a long, dense display.
How often should I feed ipomoea purpurea?
Feed sparingly. Too much nitrogen produces lush vines and few flowers. A single application of a low-nitrogen, high-phosphorus feed at planting, or a light monthly high-potash feed, supports blooming without runaway growth. Feed sparingly. Too much nitrogen produces lush vines and few flowers. A single application of a low-nitrogen, high-phosphorus feed at planting, or a light monthly high-potash feed, supports blooming without runaway growth. For a hungry bloomer that means feeding regularly — monthly — right through flowering across the main season (spring through early autumn), tapering as blooming ends.
What strength of feed for ipomoea purpurea?
Follow the flowering-feed label rate for ipomoea purpurea, or half strength if feeding very frequently. These plants genuinely use the nutrients — under-feeding shows up fast as a thin display.
What does over-feeding ipomoea purpurea look like?
Lots of lush leaves but few flowers (too much nitrogen). Scorched leaf edges and salt crust from too-strong or too-frequent feeds. Soft, sappy growth prone to aphids and mildew. Using a high-nitrogen general feed on ipomoea purpurea is the headline mistake — you grow a big leafy plant with few flowers. The second is simply under-feeding a genuinely hungry bloomer and getting a sparse, short display.
Should I flush the soil of ipomoea purpurea?
Container-grown ipomoea purpurea accumulates feed salts fast with frequent feeding — water until it drains each time and flush pots with plain water every few weeks to prevent scorch.
Keep reading
- Ipomoea purpurea care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water ipomoea purpurea — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
- How to fertilise peace lily
- How to fertilise bird of paradise
- How to fertilise hoya
- All 3899 fertilising guides in the Growli library