Hydrangea in containers

(Question)

Hello,

I am buying some hydrangea plugs this coming spring, and I want to plant them in hanging baskets.  I have a well at home and am planning to water them from the well, but the well contains sulfur and some iron.
My question is: would iron damage a hydrangea plant? and what type of soil should I be using?

I would love to hear from you.

Thank you.

(Answer)

First of all, the answer to your question about any detrimental effects that the iron in your well-water might have on hydrangea plants is quite simple–using well-water would not be detrimental to the plants. In fact, iron is important for good plant growth; but the iron uptake by plants is dependent upon the type of soil (pH) they are grown in. Most soils contain iron; however, its availability to plants is low unless the soil has a lower pH (more acidic) and the iron can be released in a form that is available to the plant through its roots.

You do not mention what kind of hydrangea plugs you intend to plant in hanging baskets. Hydrangeas become relatively large shrubs–even dwarf Hydrangea macrophylla cultivars such as ‘Pia’ or varieties in the City-line Series grow to at least 3 ft. X 3 ft. Many can be successfully grown in large containers if they are kept consistently moist with good drainage and appropriate fertilization. However, growing hydrangeas in hanging baskets would be a major challenge. The containers would have to be a substantial size; the weight including a good moisture retentive potting soil (high organic content) would be significant–probably not practical to hang unless you have a strong structure which would support the weight.

Perhaps you should consider growing your hydrangea plugs in non-hanging containers. Use a good-quality potting soil such as Pro-mix. [You may decide to transplant them into your garden once they have grown to a more mature size]. In addition to the soil and water requirements needed for optimal growth, hydrangeas generally prefer part sun–morning sun and afternoon shade. If in fact, the hydrangea plugs are Hydrangea macrophylla (big-leaf hydrangea),  you are probably aware that the soil pH will affect the flower colour–blue in acidic soils (low pH) and pink in more alkaline soils (higher pH). Adding aluminum sulphate to the soil will make the flowers bluer while adding lime will make the flowers pinker. Add the preferred amendment to the soil before the plants have flowers.

Hydrangeas are beautiful flowering shrubs that will provide many years of pleasure if they are grown in optimal conditions. For more information on growing hydrangeas, you might want to read more–here are a couple of excellent sites: https://www.hydrangeashydrangeas.com/planting_fert.html and https://hydrangeaguide.com/growing-hydrangeas-in-pots-potted-hydrangeas/

Thanks for contacting the Toronto Master Gardeners. Good luck with growing your hydrangeas.