Fertilising guide
How to fertilise Monkey flower (Mimulus × hybridus)— schedule & NPK
Also called Monkey flower, Hybrid monkey flower, Musk flower.
More about monkey flower
About Monkey flower
Mimulus × hybridus · also called Monkey flower, Hybrid monkey flower · flowering
Hybrid monkey flowers are cool-season annuals bearing tubular, snapdragon-like blooms in vivid reds, oranges, yellows, and bicolours, often marked with contrasting spots. They excel in cool, moist conditions in spring and early summer, making them ideal for shady borders, pots, and streamside plantings. They tend to decline in summer heat but can be revived in autumn.
Growth habit: Bushy, compact mound with soft, slightly hairy, opposite leaves and tubular five-lobed flowers borne in succession from leaf axils
Watch for — Heat collapse and summer dormancy: Hybrid monkey flowers are bred for cool seasons and shut down or die back when temperatures consistently exceed 24–27°C. This is normal — cut back spent stems, reduce watering and feeding, and many plants will regenerate in autumn when temperatures drop.
What fertiliser monkey flower actually wants — and why
Monkey flower 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 monkey flower: 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 monkey flower, 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 monkey flower:
Feed every 2 weeks with a balanced liquid fertiliser (e.g. 10-10-10) during active spring growth. Avoid high-nitrogen feeds which promote foliage over flowers. Reduce or cease feeding when summer temperatures exceed 25°C and plants slow down. Treat that as every 2 weeks 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 monkey flower 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 monkey flower
Half strength is the safe default for monkey flower — 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 monkey flower first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the monkey flower watering schedule.
Signs you are over-feeding monkey flower
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for monkey flower:
- 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.
Signs you are under-feeding monkey flower
- Uniformly pale or yellow-green leaves, oldest first.
- Noticeably small new leaves and stalled growth in good light and season.
- A generally tired, lacklustre look despite correct watering and light.
If the symptoms point at watering, light or roots rather than nutrition, the full monkey flower care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of monkey flower 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 monkey flower
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 monkey flower — frequently asked questions
What fertiliser does monkey flower 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. Monkey flower 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 monkey flower?
Feed every 2 weeks with a balanced liquid fertiliser (e.g. 10-10-10) during active spring growth. Avoid high-nitrogen feeds which promote foliage over flowers. Reduce or cease feeding when summer temperatures exceed 25°C and plants slow down. Feed every 2 weeks with a balanced liquid fertiliser (e.g. 10-10-10) during active spring growth. Avoid high-nitrogen feeds which promote foliage over flowers. Reduce or cease feeding when summer temperatures exceed 25°C and plants slow down. Treat that as every 2 weeks 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 monkey flower?
Half strength is the safe default for monkey flower — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding monkey flower 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 monkey flower 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 monkey flower?
Flush the pot of monkey flower 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.
Keep reading
- Monkey flower care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water monkey flower — 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 foxglove 'camelot'
- How to fertilise strawberry foxglove
- How to fertilise delphinium 'pacific giant'
- All 6887 fertilising guides in the Growli library