 Soil types and soil preparation:
Hydrangeas will grow in most soil types but thrive in well drained richly composted soils. The colour of the bloom will reflect the acidity or sweetness of the soil. Blue and mauve blooms with a blue eye reflect an acidic soil (when planted next to concrete paths they will be invariably blue) and red, pink and mauve blooms with red eyes reflect a sweeter alkaline lime rich soil.
White blooms will always be white no matter the soil type but the colour of the eye will indicate the soil type.
Consequently when you want blue or mauve blooms then add Aluminium Sulphate to the soil around the bush and for redder blooms add lime. Apply when you prune.
Use blood and bone as a general side dressing for fertiliser and dig in lots of compost around the base. Apply when you prune.
Pruning:
Please note well the following – the secret to pruning Hydrangeas is firstly “when to prune” and then “how to prune”. Let me explain.
New growth after pruning can be damaged by frost and although you will still get growth you will not get as many flowers. If you prune incorrectly you will get the same result – very few flowers.
Rule number one – “when to prune” is to start your serious pruning when you are reasonably sure the danger of heavy frosts are past. So perhaps late August early September ?
Rule number two – “how to prune” consists of a number of general guidelines which should be fairly easy to follow. However this should be tempered by resisting the urge to prune for the sake of it so choose the options below that best reflect your bush.
- Remove all overhanging branches that are in the way or intruding on other plants – cut them back at the base.
- Remove all dead wood – again cut back to the base.
- Remove all thin, weak or crossing stems – you need to get inside the bush to do this.
So far you could apply the above to all Hydrangeas – here come the tricky bits!!
- Look for stems that flowered last season – you should be able to identify them because they will have bits of dried flower on them – cut these stems back to above a nice fat pair of buds – the fat buds are the ones most likely to produce lots of flowers – don’t worry if you have to lop a fair bit off but don’t get too carried away.
- Next look for any other stems that have no evidence of having produced flowers and cut them back by a third – down to a nice fat pair of promising buds. However it is these stems that many gardeners are happy to leave alone – the choice is yours. Remember that fat buds equate to strong stems and strong stems equate to lots of flowers.
Marigold Botanicus – House & Garden Church Corner – www.housegarden.co.nz
July 2008
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