Gardenia augusta Magnifica (Gardenia jasminoides)

Magnifica is the large flowered form of the group, a broader and heavier shrub than the others, with big deep green leaves that hold a lacquered shine. The blooms are the point of difference: substantial doubles, white opening and ageing to cream, heavily scented, and carried in smaller numbers than the fine leaved types produce because each one is so much bigger. It fills a border on its own, works as a loose low screen, and carries a large pot where a smaller gardenia would look thin.

Big leaves, big flowers and yellowing from the bottom up

Part shade with protection from hot afternoon sun is the position, as the specs list, and it will take more sun in a cool district than it ever will in the subtropics. Plant into acidic, free draining soil with plenty of compost, mulch to keep the roots cool, and allow around 80cm to a metre between plants where several are run together as a screen. Even moisture matters more than volume; buds drop if the plant dries out or is shifted while it is setting them.

Yellowing is the classic gardenia failure, and on Magnifica it usually starts as magnesium hunger rather than the alkaline soil trouble the smaller forms run into. A canopy of big leaves carrying big flowers pulls magnesium out of the plant faster than a fine leaved gardenia does, and the drain runs hardest right through the flowering flush. The tell is on the older leaves low down: yellow creeping in from the margins and leaving a green wedge along the midrib, while the tips stay dark. General and high potassium fertilisers make it worse, because potassium competes with magnesium at the root. Water in Epsom salts as the flush starts and again once it finishes, feed with a food made for acid loving plants rather than a rose or lawn product, and test the pH before reaching for iron, since pale new leaves with dark veins point to alkaline ground and locked up iron instead, which is a different fix.

When size is the reason to choose Magnifica

Choosing between the augusta forms comes down to scale. Florida is the tidier, mid sized plant for a clipped low hedge or matched pots, and it flowers more freely with smaller blooms. Grandiflora Star breaks the pattern with single, flat, star shaped flowers instead of doubles, for anyone who finds the double form too formal. Magnifica is the one to buy when you want size in both leaf and flower: a specimen beside a doorway, a deep border that needs filling, or a large container. It is the poorest choice of the three for tight clipping. More in flowering plants.

Pruning a heavy canopy and feeding it

Prune once the main flush is over, shortening stems by a third at most and taking out thin twiggy wood at the base so air moves through what is a dense canopy. Avoid cutting after early autumn. Feed in spring and again in midsummer with an azalea and camellia food, water it in well, and top up mulch afterwards. Scale and mealybug settle into the leaf joints on plants this heavily furnished and bring sooty mould with them, so check undersides while you prune and treat with horticultural oil in warm weather.

Choosing a size

This plant is available in 5 sizes, from 140mm up to 300mm, priced from $16.95 to $88.95 per plant. The size shown is the pot the plant arrives in, which is the rootball, not the height of the plant. These are younger plants, priced for planting in quantity, and they establish quickly once in the ground. Not sure which to choose? Read our guide to when to plant in Australia.