Q. My kids sent me a hydrangea for the holidays. I know I have to keep it as a houseplant. When I lived in New York, mine were huge outdoors. What do I need to do keep them alive and thriving?
A. Hydrangeas are not meant for planting in our climate and soils. Hydrangeas given as gifts are like poinsettias; intended to be grown in greenhouses for a one-time gift event. But what the heck, give it a shot!
There are some varieties of hydrangeas that are more suitable for growing outdoors than others. Western Sunset Garden Book has recommended varieties you can try. If you are lucky enough to have gotten one of these varieties as a gift then you may have a fighting chance of keeping it alive.
They need a bright location on the north or east side with filtered light. Add compost to the soil at the time of planting. The plants need an organic surface mulch that decomposes, enriching the soil, such as wood chips. It should be fertilized with an acid fertilizer every 6 to 8 weeks.
If you want to go whole hog on this plant then get some aluminum sulfate and apply it to the soil when you plant and in early spring. Aluminum sulfate does a better job acidifying the soil than sulfur. Acidifying the soil helps keep the flowers of vibrant blue color.
You are fighting an uphill battle on this one but if you really want it to work you must spend time and money on this plant with soil preparation, mulch and specialized fertilizers such as aluminum sulfate.
Otherwise, I would not bother and enjoy it for what it was intended; a gift on a special occasion from loved ones.