Chestnut Dioon

Chestnut Dioon (Dioon edule) is a Mexican cycad that holds a perfectly symmetrical rosette of stiff, blue green fronds above a slowly thickening trunk. It reaches about 1.5m tall and wide, and takes decades to get there. That slowness is the appeal: it keeps its shape without shaping, and it handles drought, heat, poor soil and salt spray.

Why you'll love it

• It never outgrows the spot. At roughly 1.5m in each direction after many years, it can sit beside a path or pool and never need cutting back.
• Built for hard sites. Drought and heat tolerant, happy in poor soil, and salt tolerant enough for a coastal front garden.
• Clean and quiet. No flowering mess and almost no litter, just an occasional old frond to remove.
• An architectural form. The rosette reads as sculpture, which is why designers use it where a shrub looks soft.

Where it works best

Feature planting. One plant against a rendered wall, gravel or paving carries a courtyard. Set it where you see it from indoors.

Poolside and rockeries. It tolerates reflected heat, salt and chlorine splash, and drops little litter near water. In a rockery, plant it high where drainage is sharpest.

Pots and containers. A wide, heavy pot suits it for years, since the root system is slow and undemanding.

One warning. All cycads are highly toxic to dogs, cats and livestock. The seeds are the worst part, and even a small amount can cause liver failure, so do not plant it where a dog digs or chews.

Growing Chestnut Dioon in Australia

Position and climate. Full sun to partial shade, with the bluest fronds in an open sunny spot. It suits tropical, subtropical, warm temperate, arid and semi-arid and Mediterranean gardens. It takes light frost only, so in cold inland and frosty southern gardens grow it in a pot you can shelter.

Soil. Sharp drainage matters more than fertility. Sandy or gravelly soil is ideal; on clay, plant high on a mound with coarse material through the backfill. Wet feet in winter is the one thing that kills it.

Water and feed. Water weekly for the first summer, then only in long dry spells. A slow release fertiliser with trace elements once in spring is enough, and a little magnesium keeps old fronds green.

Pruning. Cut old or damaged fronds off close to the trunk once the new flush has hardened. New fronds come in a single push every year or two, so leave the old ring in place until the replacement is firm.

What to expect when it arrives

This cycad is sold in 45L and 60L, and both represent many years in the nursery, which is why an advanced dioon costs what it does. You are buying a formed trunk and a full crown, not something that fills out next season.

Cycads travel well. The fronds are rigid and hold little water stress, so expect yours to arrive as it left. Plant at the same depth it sat in the pot, water in, then leave it alone. Delivered Australia wide, delivery from $29.95, and advanced and large stock is freighted at cost. Every plant carries our 30 day healthy plant guarantee.

Plant care guides and related reading

• The complete cycad care guide
• Architectural plants for designer gardens
• Poolside planting options
• Rockery and dry garden plants

Common questions

How fast does it grow?

Very slowly. Expect one new ring of fronds every one to two years and a few centimetres of trunk in a decade. Buy the size you want to look at.

Is it safe around dogs?

No. Every part is toxic to dogs and cats, and the seeds are the most dangerous. Plant it out of reach if your dog chews or digs, and clear any fallen seed.

Can it stay in a pot permanently?

Yes, and it is one of the better cycads for it. Use a wide pot with free draining mix and repot every five years or so.

How much frost will it take?

Light frost once established, and no more. Young plants are more vulnerable, so protect them for their first two winters.