Hydrangea renate Steiniger Is A Showy Hydrangea With Flowers That Turn To The Most Brilliant Blue As They Open. Hydrangeas Can Change Colour Depending On The Acidity Of The Soil, So If You Garden On Alkaline Soil & Want To Keep The Blue Flowers From Turning Pink, Grow It In A Container Of Ericaceous Compost.plant Into Humus-rich, Moisture Retentive Soil. Keep The Wonderful Blue Colour By Growing This Hydrangea In Acid Soil.after Carekeep Plants Well Watered Especially In Dry Weather.keep Faded Flowers On The Stems Over Winter To Protect Buds From Frost. The Dried Flower Heads Also Look superb In Winter Arrangements.prune In Spring, Cut Flowering Stems Back To A Healthy Pair Of Buds.on Established Plants Prune Out A Third Of Old Stems In Spring To Encourage Fresh New Growth.flowers July-augustheight Up To 150cm/5ft.