Question
I planted my hydrangea a couple of months ago. It`s grown really well, only I`ve noticed the stem is covered in black spot`s. The area it`s planted in has had lot`s of compost added to it, but the soil is heavy clay & a former industrial site. What is your diagnosis & advice? Please help. Stu

Answer
Hi Stuart,
Thanx for your question.  Usually, the spots would be on the leaves.  It sounds like a fungal infection to me.  Have you noticed any aphids (small green, yellow, brown insects that suck the sap out of leaves and stems)?  There is a remedy for fungal blackspot.

Try this:

Mix 1 Tbsp baking soda in 1 gallon of water and add a tiny drop of liquid dish detergent or 1 Tbsp of Murphy's Oil soap. Spray once a week preferably early in the morning.

Hydrangeas will develop black spot if planted to close to a house or other shrubs.  They need good circulation and need at least 6 hours of sun per day.  If you are in a particularly hot climate, avoid the sun of the afternoon.

I hope this helps.
Tom