How to grow Soursop in New Zealand
Soursop, or guanabana, is a small tropical tree with large, soft-spined green fruit and white, fragrant, sweet-sour flesh. It does not tolerate cold, is easily damaged by frost and wind, and needs steady tropical warmth, so in New Zealand it is not suited outdoors anywhere, even in the Far North. It is only worth trying in a heated glasshouse.
At a glance
When to plant by region
| Region | When to plant | Regional note |
|---|---|---|
| Northland | Not suited | Not suited outdoors in New Zealand. A strict tropical that will not take cold, even in the Far North. |
| Auckland | Not suited | Not suited outdoors in New Zealand. A strict tropical that will not take cold, even in the Far North. |
| Waikato & Bay of Plenty | Not suited | Not suited outdoors in New Zealand. A strict tropical that will not take cold, even in the Far North. |
| Central North Island | Not suited | Not suited outdoors in New Zealand. A strict tropical that will not take cold, even in the Far North. |
| Wellington & Lower North Island | Not suited | Not suited outdoors in New Zealand. A strict tropical that will not take cold, even in the Far North. |
| Nelson & Marlborough | Not suited | Not suited outdoors in New Zealand. A strict tropical that will not take cold, even in the Far North. |
| Canterbury | Not suited | Not suited outdoors in New Zealand. A strict tropical that will not take cold, even in the Far North. |
| Otago & Southland | Not suited | Not suited outdoors in New Zealand. A strict tropical that will not take cold, even in the Far North. |
| Central Otago | Not suited | Not suited outdoors in New Zealand. A strict tropical that will not take cold, even in the Far North. |
Not to be confused with: Cherimoya and custard apple, relatives in the same genus that are much more cold tolerant and better suited to frost-free northern New Zealand gardens.
Where to plant
Soursop does not tolerate cold, is highly susceptible to frost and is easily damaged by strong wind. Even the warmest parts of New Zealand are far too cool for it, which is why our regional calendar marks it unsuitable in every region.
If you want to try one, grow it in a large pot in a heated glasshouse or conservatory kept warm through winter, in well-drained, slightly acid mix.
How to plant
- Sow fresh seed, washed and planted within about a month of harvest, when most will germinate in 15 to 30 days in warmth. Grafted plants of better varieties are rare in New Zealand.
- Grow the seedling on in a large container of free-draining potting mix in the warmest, brightest place under glass.
- Mulch the surface of the pot, as the roots are shallow, and keep the plant out of draughts.
Watering and feeding
Keep the mix evenly moist during warm months and water less in winter, never letting the pot sit in water. Feed lightly through the growing season with a balanced fertiliser.
Harvesting
Unripe fruit is dark green. Pick when the skin lightens to a slightly yellowish green, then let the fruit soften on the bench until it gives to gentle pressure. Eat the white flesh fresh or in drinks, and discard the skin and the black seeds.
Pests and diseases
In a glasshouse, sap-sucking insects and fungal rots are the main problems.
Pests to watch for
- Mealybug White, cottony insects on stems, leaves and fruit.
- Scale Small bumps on stems and leaves, often with sooty mould.
Diseases to watch for
- Anthracnose Dark, sunken spots on leaves, flowers and fruit in humid conditions.
Common questions
Can soursop grow outdoors in New Zealand?
No. Soursop does not tolerate cold, is highly susceptible to frost and is easily damaged by wind. It needs a heated glasshouse anywhere in New Zealand.
Is soursop the same as custard apple?
They are relatives in the same genus, but soursop is larger, spinier and far less cold tolerant. Cherimoya and custard apple suit frost-free northern gardens much better.
When is soursop ripe?
When the dark green skin lightens to a slightly yellowish green. Pick it then and let it soften on the bench until it gives to gentle pressure.
Can I grow soursop from seed?
Yes. Wash fresh seed and sow it within about a month of harvest; most seed germinates in 15 to 30 days in warmth. Seedlings need constant warmth and bright light, so in New Zealand they only thrive in a heated glasshouse.
Do I eat the seeds?
No. Discard the skin and the black seeds, and eat only the white flesh.
Sources we checked: University of Hawaii CTAHR: Soursop (F_N-22); UF/IFAS Gardening Solutions: Sweetsop, soursop and atemoya.