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Fertilising guide

How to fertilise Campsis radicans (Campsis radicans)— schedule & NPK

Also called trumpet vine, trumpet creeper, cow-itch vine.

More about campsis radicans

About Campsis radicans

Campsis radicans · also called trumpet vine, trumpet creeper · flowering

A vigorous deciduous climber native to the southeastern US, prized for clusters of large orange-to-scarlet trumpet flowers from summer to autumn that draw hummingbirds and bees. It self-clings by aerial rootlets, scaling walls and fences fast. Robust and hardy, it can be invasive and suckering, so plant where its rampant spread can be controlled.

Growth habit: Extremely vigorous, self-clinging deciduous climber that attaches via aerial rootlets and also spreads by underground suckers. Fast-growing and potentially invasive; needs sturdy support and regular containment to stop it overwhelming structures or neighbouring plants.

Watch for — Few or no flowers: Most often from too much shade, excess nitrogen, or impatience — young plants can take 2-3 years to bloom. Site in full sun and avoid rich feeding.

What fertiliser campsis radicans actually wants — and why

Campsis radicans is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.

A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula.

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 campsis radicans: 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 campsis radicans, 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 campsis radicans:

Generally needs little to no feeding; rich diets reduce flowering. If growth is weak, a light spring application of a low-nitrogen, higher-potassium fertiliser is sufficient. Avoid high-nitrogen lawn feeds nearby. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.

The dormant-season rule matters more than the exact interval: skip feeding entirely when campsis radicans 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 campsis radicans

Half strength is the safe default for campsis radicans — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.

Feeding always goes onto already-damp soil, never dry roots — water campsis radicans first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the campsis radicans watering schedule.

Signs you are over-feeding campsis radicans

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for campsis radicans:

Signs you are under-feeding campsis radicans

If the symptoms point at watering, light or roots rather than nutrition, the full campsis radicans care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

Flush the pot of campsis radicans with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.

Organic vs synthetic feeds for campsis radicans

Organic options

A diluted seaweed or worm-casting feed, or fish emulsion if you can tolerate the smell indoors. UK: Westland or Baby Bio Organic, dilute seaweed; US: Espoma Indoor! or Neptune's Harvest fish & seaweed. Slow, gentle and hard to overdo.

Synthetic / liquid feeds

A general-purpose houseplant liquid at half strength — UK: Baby Bio, Westland Houseplant Feed or Phostrogen; US: Miracle-Gro Indoor Plant Food or Schultz. Convenient and fast-acting; the only risk is overdoing it.

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 campsis radicans — frequently asked questions

What fertiliser does campsis radicans need?

A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula. Campsis radicans is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.

How often should I feed campsis radicans?

Generally needs little to no feeding; rich diets reduce flowering. If growth is weak, a light spring application of a low-nitrogen, higher-potassium fertiliser is sufficient. Avoid high-nitrogen lawn feeds nearby. Generally needs little to no feeding; rich diets reduce flowering. If growth is weak, a light spring application of a low-nitrogen, higher-potassium fertiliser is sufficient. Avoid high-nitrogen lawn feeds nearby. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.

What strength of feed for campsis radicans?

Half strength is the safe default for campsis radicans — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.

What does over-feeding campsis radicans look like?

Brown, crispy leaf tips and edges with no sign of underwatering. A white, crusty salt deposit on the soil surface or pot rim. Weak, pale, stretched new growth that flops. Lower leaves yellow and drop while the soil is correctly watered. Feeding campsis radicans year-round on a fixed schedule, including dark winter months, is the most common mistake — it cannot use the nutrients in low light and the surplus simply burns the roots and crusts the soil.

Should I flush the soil of campsis radicans?

Flush the pot of campsis radicans with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.

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