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Fertilising guide

How to fertilise Monkeyflower (Mimulus guttatus)— schedule & NPK

Also called Monkeyflower, Common Monkeyflower, Yellow Monkey Flower, Seep Monkeyflower.

More about monkeyflower

About Monkeyflower

Mimulus guttatus · also called Monkeyflower, Common Monkeyflower · flowering

Mimulus guttatus is a short-lived herbaceous perennial native to moist stream banks, seeps, and wet meadows across western North America, now naturalised in the British Isles where it can be invasive near waterways. It demands consistently wet to waterlogged soil and full sun to light shade, producing bright yellow trumpet-shaped flowers spotted red in the throat from late spring through summer. The key care priority is never letting the soil dry out — even brief drought causes rapid wilting and collapse. Toxicity to cats and dogs is not confirmed by the ASPCA; treat with caution.

Growth habit: Low, spreading herbaceous perennial with creeping or ascending stems; self-seeds freely and can naturalise aggressively near water.

What fertiliser monkeyflower actually wants — and why

Monkeyflower 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 monkeyflower: 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 monkeyflower, 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 monkeyflower:

Apply a general-purpose liquid fertiliser monthly during the growing season; plants in pond margins often require no additional feeding if the water is nutrient-rich. Treat that as monthly 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 monkeyflower 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 monkeyflower

Half strength is the safe default for monkeyflower — 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 monkeyflower first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the monkeyflower watering schedule.

Signs you are over-feeding monkeyflower

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

Signs you are under-feeding monkeyflower

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

Flushing and leaching the salts

Flush the pot of monkeyflower 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 monkeyflower

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 monkeyflower — frequently asked questions

What fertiliser does monkeyflower 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. Monkeyflower 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 monkeyflower?

Apply a general-purpose liquid fertiliser monthly during the growing season; plants in pond margins often require no additional feeding if the water is nutrient-rich. Apply a general-purpose liquid fertiliser monthly during the growing season; plants in pond margins often require no additional feeding if the water is nutrient-rich. Treat that as monthly 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 monkeyflower?

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

What does over-feeding monkeyflower 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 monkeyflower 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 monkeyflower?

Flush the pot of monkeyflower 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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