Chestnut Dioon Dioon edule

Chestnut dioon holds a symmetrical crown of stiff blue-grey-green fronds on a trunk that thickens over decades rather than years, pushing one flush at a time and sometimes skipping a season altogether. That slowness and the hard glaucous foliage are the appeal, because it looks tropical while behaving like a plant from the dry limestone country of eastern Mexico, which is where it comes from. It works as a single feature in a gravel bed, a courtyard or a large pot.

Water it like a succulent, not a fern

Full sun through to part shade suits it, and it tolerates more cold than most cycads, which widens the map well beyond the frost-free coast. Water is a low ask once it is established, and growth is slow enough that the size you buy is close to the size you live with for a long while. Soil is where people go wrong. This plant wants a gritty, sharply drained profile, and the standard failure is treating it as a tropical foliage plant: regular irrigation, rich soil that stays damp, a summer of good intentions, and then a soft caudex and a crown that pulls away in the hand. Water deeply but infrequently through the warm months, back right off through winter, and never plant it into a lawn zone on a sprinkler timer. It also does well in a pot, where drainage is easy to control and a heavy container suits the weight of the crown. Every part of the plant is toxic to dogs and livestock, seeds included.

Chestnut dioon compared with its bigger relatives

Giant dioon is the same genus with an opposite temperament: rainforest origins, longer arching flat leaves, soft new growth that scorches in harsh sun, and a trunk that eventually lifts it to small-tree scale. Edule stays compact, blue and stiff, and is the one to plant in an open dry position. For a bigger arching crown as a single collector specimen, Encephalartos whitelockii is the plant, though it wants more warmth and more shelter. Choose chestnut dioon if your site is exposed, your soil is poor and you want a cycad that asks for very little. It is listed with the rest of our advanced trees.

Protecting the new flush

There is very little pruning to do. Remove fronds only when they have yellowed and collapsed, cutting close to the trunk, and leave the skirt of older leaves if you like the look, since it does no harm. Time any tidy-up for spring, ahead of the flush. When that flush appears the fronds are soft and easily bent or scarred, and they harden in that shape, so keep mowers, dogs and foot traffic away from the plant for several weeks. Feed lightly once in spring with a slow-release fertiliser, because a plant pushed with nitrogen puts up weak elongated leaves that never look right. Cones on mature plants can be left in place.

Choosing a size

This plant is available in 2 sizes, from 45L up to 60L, priced from $779.00 to $1319.00 per plant. The size shown is the pot the plant arrives in, which is the rootball, not the height of the plant. Every size here is established stock rather than a starter plant, so this line is intended for immediate effect rather than for growing on. Not sure which to choose? Read our guide to when to plant in Australia.