my Gardenia radicans and Gardenia jasminoides var.
veitchii have yellow leaves and no flowers. I've tried fertilising
them, but they're still not doing well. They're in a relatively
new garden between the house and a new path, with a watering system
and bark mulch so they don't dry out. All the other plants in the
same garden are doing well. Can you help?
almost certainly suffering from lack of iron. Gardenias are acid-loving
plants and if the soil is slightly alkaline they can't take up iron
from the soil.
It's quite common for
lime seeping from new concrete to affect soil in nearby gardens,
raising the pH, so acid-loving plants like gardenias and azaleas
are adversely affected.
But there's an easy solution.
Simply water your gardenias with a solution of iron sulphate and
water - around 150g in half a bucket of water. Give them a good
soaking. The change should be quite dramatic. New growth of deep
green leaves with flower buds should occur within a few weeks during
You can buy iron sulphate
from most garden centres, or use iron chelate fertiliser - there
are several brands available - which specifically alleviates iron
deficiency in acid-loving plants.
Gardener, Issue 143, 2004, Page 26
Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.