Fertilising guide
How to fertilise Mountain Soursop (Annona montana)— schedule & NPK
Also called Mountain Soursop, Wild Soursop.
More about mountain soursop
About Mountain Soursop
Annona montana · also called Mountain Soursop, Wild Soursop · tropical
An evergreen tropical tree closely related to soursop (Annona muricata) but more cold-tolerant and faster-growing, native to the Caribbean and Central America. Produces large, spiny green fruits with aromatic white flesh. Suitable for warm subtropical climates in USDA zones 9b–11. Performs best in full sun with consistent moisture and well-drained soil.
Growth habit: Upright, fast-growing evergreen tree with a broadly spreading crown
Watch for — Spider mites in low humidity: Fine webbing and stippled, pale leaves indicate spider mite infestation, particularly in dry indoor conditions. Increase humidity, mist foliage, and treat with neem oil or insecticidal soap; repeat every 5–7 days.
What fertiliser mountain soursop actually wants — and why
Mountain Soursop 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 mountain soursop: 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 mountain soursop, 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 mountain soursop:
Feed with a balanced slow-release fertiliser (NPK 8-3-9 or equivalent) three times a year — in early spring, early summer, and early autumn. Supplement with a high-potassium liquid feed during fruit development to improve flavour and yield. 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 mountain soursop 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 mountain soursop
Half strength is the safe default for mountain soursop — 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 mountain soursop first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the mountain soursop watering schedule.
Signs you are over-feeding mountain soursop
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for mountain soursop:
- 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 mountain soursop
- 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 mountain soursop care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of mountain soursop 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 mountain soursop
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 mountain soursop — frequently asked questions
What fertiliser does mountain soursop 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. Mountain Soursop 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 mountain soursop?
Feed with a balanced slow-release fertiliser (NPK 8-3-9 or equivalent) three times a year — in early spring, early summer, and early autumn. Supplement with a high-potassium liquid feed during fruit development to improve flavour and yield. Feed with a balanced slow-release fertiliser (NPK 8-3-9 or equivalent) three times a year — in early spring, early summer, and early autumn. Supplement with a high-potassium liquid feed during fruit development to improve flavour and yield. 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 mountain soursop?
Half strength is the safe default for mountain soursop — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding mountain soursop 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 mountain soursop 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 mountain soursop?
Flush the pot of mountain soursop 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
- Mountain Soursop care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water mountain soursop — 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 cherapu
- How to fertilise magenta cherry
- How to fertilise guapeva
- All 8452 fertilising guides in the Growli library