[Cedrina]

Hi, hoping someone could offer some advice! On the instruction of my landlord, I cut back two hydrangeas in the front garden (mopheads). They are now putting on lots of new growth but the leaves are yellow/acid green. I'm assuming there's a deficiency but not quite sure. Any advice welcome!

[Cedrina]

Ok apologies and note to self to use search function!
Found the answer quite prominentlyon the front page.

Iron Deficiency.
Deficiency symptoms: Pale green or yellow leaves, with leaf veins remaining conspicuously green, most obvious on younger leaves. The yellowing spreads over the whole leaf until it becomes almost completely bleached white.

Cause: Your plant requires the nutrient Iron (Fe), without it a chlorosis of the leaves begins. This deficiency may be because your soil is too low in organic matter, or if your organic matter levels are in fact adequate, it may be because your plant cannot extract the nutrient. You see Iron has low mobility in compacted and high pH soils (alkaline/limey).

End result if left unresolved: Leaf fall, shoot dieback, and unsatisfying flower and fruit production.

Solution: For a quick fix apply a liquid feed designed for use on acid-loving/lime-hating plants to the root-zone and foliage of your affected plants. Look for liquid feeds labelled Sequestrene or chelated iron. Another way to also decrease your ph, or make your soil more acid is by applying sulphate of iron to the soil around the plants at a rate of 100g per metre squared for each drop in ph point.