Aji amarillo is the chili I get asked about most after the obvious habanero and bhut jolokia questions. People taste it in a Peruvian restaurant, fall in love with that fruity, slightly sweet heat, and then come to me asking why their plants did nothing. So this is the post I should have written a few seasons back.

I’ve grown aji amarillo (Capsicum baccatum) in Sydney for five years now. The first two were a write-off. The third was decent. Last season I pulled close to 4kg off two plants, which for baccatums in our climate is honestly pretty good.

Why most Sydney growers fail with this one

Baccatums are slow. They want a long season, and they don’t fruit well until the plant is large and well-established. If you treat aji amarillo like a regular capsicum and start seeds in September, you’ll be lucky to get a handful of pods before autumn shuts things down.

The other issue is heat. Not air temperature - root temperature. These plants come from Andean valleys where days are warm but nights are cool. They actually do well in Sydney’s milder coastal microclimates as long as the roots stay happy. Black plastic pots in full afternoon sun cook them.

My start-to-finish approach

I now sow aji amarillo seeds in late June, indoors, on a heat mat at 28°C. Germination is slow - sometimes three weeks, occasionally four. I’ve stopped panicking about it. Just keep the medium moist, not wet, and they’ll come.

Pot them up at the cotyledon stage into 100mm pots. I use a 50/50 mix of seed-raising mix and worm castings. They sit under a grow light until late September when overnight temps reliably stay above 12°C.

For final containers, I use 40-litre fabric pots. Not the cheap ones - the heavier-duty grow bags. Aji amarillo plants get massive if you let them. Mine routinely hit 1.8 metres and need staking.

Feeding schedule that actually works

I made the mistake early on of feeding heavy nitrogen all season. Got beautiful, lush plants and almost no fruit. Now I do this:

• October to mid-November: weekly seaweed solution and a balanced organic feed
• Mid-November onwards: switch to a high-potassium tomato fertiliser
• Through summer: fortnightly worm castings tea, plus a Epsom salts foliar spray once a month

The magnesium spray makes a real difference with baccatums in pots. The leaves stay deep green right through to autumn.

Pruning - the bit nobody mentions

This is where I changed my approach completely. Aji amarillo branches in a crown pattern, then keeps branching in pairs. Most growers leave them be. I now do a hard topping at about 30cm tall, then selectively prune to keep three or four main stems.

Yes, this delays first flowers by a few weeks. But the plant becomes much sturdier, the fruit gets better airflow, and total yield goes up significantly. The Chile Pepper Institute at New Mexico State has some research on baccatum pruning if you want to go down that rabbit hole.

When to harvest

Aji amarillo pods turn from green through orange to a deep golden yellow when fully ripe. Don’t pick them green - they’re hot but lack the fruity character that makes them special. The flesh should give slightly when you squeeze a ripe pod.

I usually start harvesting in late February in Sydney, with the main flush running through March and into April if we get a mild autumn. Last year I was still picking ripening pods in early May from plants I’d brought under shelter.

Storage and use

Fresh aji amarillo blends into the most incredible paste. Just deseed, simmer in a bit of water and oil for ten minutes, then blend smooth. Freezes brilliantly in ice cube trays.

I also dehydrate a portion of every harvest. Dried aji amarillo (called aji mirasol when dried this way) has a different flavour - more raisin-like, less bright. Both are worth having.

A few honest warnings

Aji amarillo is not a beginner chili. If this is your first season growing chillies, get a habanero or jalapeño season under your belt first. The patience required for baccatums will frustrate someone who hasn’t already learnt the rhythm of growing chillies in our climate.

But once you crack it - and Sydney is one of the better Australian cities for this variety - you’ll have a chili that nothing in the supermarket comes close to matching. Worth the wait.

If you want seeds, I usually have aji amarillo available from late winter through to early summer. Check the seed page on the site or shoot me an email if you’re after a specific quantity.