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Plant care

Mountain Soursop (Wild Soursop) care

Annona montana

Also called Mountain Soursop, Wild Soursop.

RHS H1bUSDA 9b–11Mildly toxic to petsIndoor 10–15 m tall (33–50 ft) in the ground

Watering rhythm

Direct sun (at least 4-6 hours)

Twice weekly when establishing; weekly once mature

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Light

Direct sun (at least 4-6 hours)

Soil

Fertile, well-drained loamy or sandy loam soil

Humidity

60–85%

Temp

15–35°C

Pet safety

Mildly toxic to pets

Mature size

10–15 m tall (33–50 ft) in the ground

Care at a glance

Light

Aim for at least 4-6 hours of direct sun on the leaves. Requires abundant direct sunlight — place in a south- or west-facing position with at least 6 hours of sun. While partial shade is tolerated, fruit set and overall vigour are significantly better in full sun. When grown indoors or under glass, position as close to the glass as practical. If your only bright window faces south, that's perfect for mountain soursop — same window any aroid would fry on.

Watering

Watering mountain soursop: twice weekly when establishing; weekly once mature. The number that matters isn't the day of the week — it's how dry the top 2-3 cm of the pot feels. A finger in the soil tells you more than a watering app. After every watering, tip the saucer. Prefers consistently moist but well-drained soil. Water regularly during the growing and fruiting season. Mountain soursop is more drought-tolerant than Annona muricata once established, but prolonged drought causes leaf drop and fruit abortion. Allow the top few centimetres of soil to dry between waterings.

Soil and pot

Mountain Soursop grows best in fertile, well-drained loamy or sandy loam soil. Prefers rich, well-drained loamy soil with a slightly acidic to neutral pH (6.0–7.0). Amend heavy soils with organic compost and coarse sand to improve drainage. Does not tolerate waterlogged conditions, which readily cause root rot. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Mountain Soursop sits happiest at around 60–85% humidity and 15–35°C (59–95°F). Thrives in warm humid tropical and subtropical conditions. In lower-humidity environments, mist foliage regularly or grow in a humid glasshouse. Low humidity combined with heat stress can trigger spider mite infestations. If you keep the room above 15–35°C year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed mountain soursop sparingly. 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. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on mountain soursop in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Root rot (Phytophthora sp.) — Waterlogged or poorly drained soil rapidly leads to Phytophthora root rot, causing yellowing leaves, wilting, and tree death. Ensure excellent drainage and avoid overhead irrigation wetting the base of the trunk.
  • 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.
  • Fruit fly infestation — In tropical regions, fruit flies (Bactrocera spp.) target ripening fruits, causing internal damage and rot. Use protein bait traps or bag individual fruits with fine mesh netting as they develop.

Propagation

From seed, which should be sown fresh at 25–28°C in moist, free-draining compost; germination takes 4–8 weeks. Grafting onto Annona muricata rootstock produces trees that fruit earlier and grow more vigorously than seedlings. Air-layering is also successfully used to propagate preferred fruiting specimens. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Mountain Soursop is mildly toxic to pets. Like all Annona species, Annona montana contains annonaceous acetogenins in its seeds, leaves, and bark. These compounds are toxic in quantity, with neurotoxic potential documented across the genus. Seeds must never be eaten. The Annona genus is documented as toxic to dogs. Not individually listed by ASPCA — exercise caution and keep all plant parts away from pets. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Mountain Soursop care — frequently asked questions

What is the common name for Annona montana?

Annona montana is most commonly called Mountain Soursop, but it is also known as Mountain Soursop, Wild Soursop. The names refer to the same species, so care instructions for Mountain Soursop apply identically to anything sold as Wild Soursop.

How much light does mountain soursop need?

Mountain Soursop grows best in direct sun (at least 4-6 hours). Requires abundant direct sunlight — place in a south- or west-facing position with at least 6 hours of sun. While partial shade is tolerated, fruit set and overall vigour are significantly better in full sun. When grown indoors or under glass, position as close to the glass as practical.

How often should I water mountain soursop?

Water mountain soursop twice weekly when establishing; weekly once mature. Prefers consistently moist but well-drained soil. Water regularly during the growing and fruiting season. Mountain soursop is more drought-tolerant than Annona muricata once established, but prolonged drought causes leaf drop and fruit abortion. Allow the top few centimetres of soil to dry between waterings. The finger-test (or lifting the pot to feel its weight) beats a fixed weekly calendar because pot size, light, and season all change how fast the soil dries.

Is mountain soursop toxic to cats and dogs?

Mountain Soursop is mildly toxic to pets. Like all Annona species, Annona montana contains annonaceous acetogenins in its seeds, leaves, and bark. These compounds are toxic in quantity, with neurotoxic potential documented across the genus. Seeds must never be eaten. The Annona genus is documented as toxic to dogs. Not individually listed by ASPCA — exercise caution and keep all plant parts away from pets.

What USDA hardiness zone does mountain soursop grow in?

Mountain Soursop is rated for USDA zone 9b–11 and RHS hardiness H1b. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Mountain Soursop deep-dive guides

Every aspect of mountain soursop care, each with its own calibrated guide:

Featured in these plant shortlists

Mountain Soursop qualifies for 4 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

Related guides

Mountain Soursop is also commonly called Mountain Soursop or Wild Soursop.