Monday, July 7th, 2008...8:54 am

Acid for Hydrangeas

TheGardenLady received this question from Martha:

How can I add acid around my hydrangeas?

Because hydrangeas like an acidic soil – especially if you want the blue blooms- you can supplement the fertilizer and add acid.  Know that not all the hydrangeas will change color. Usually it is the pink and blue hydrangeas that can have their flowers change color, not the white or red hydrangeas.

Any of the following will help: aluminum sulfate (1/4 oz. per gal. of water) which can be bought in many garden stores, egg shells, coffee grounds which you can get free, TheGardenLady was told, at places like Starbucks,  ground up orange or grapefruit peels.

You can buy Espoma Garden Sulphur, which is sold in 5 lb.bags in many garden stores. This Espoma site is a very informative website about all sorts of interesting garden information. The Espoma Company has different recommendations on using their sulphur depending on whether the plant is in a pot or in the ground, and whether it is a new planting or an established plant in the ground.

On new plants that are planted in the ground, put on the Espoma Sulphur in the spring and fall at a rate of 1/4cup sulphur per plant.

On plants that are ESTABLISHED use the Espoma Sulphur in the spring and fall but you can use 1/2 cup per plant. If you must put sulphur on your hydrangea now, use only 1/4 cup- but this is really not recommended.

If your hydrangea is in a pot, the amount you use will depend on the size of the plant and pot. One Tbsp is what is suggested because of the small amount of soil in a pot. To keep your plants healthy you should also remember to fertilize your hydrangeas as well.

Holly-tone for acid loving plants is the recommended fertilizer that is also made by the Espoma Company. For more information on changing the color of the hydrangea and fertilizing acid loving plants you can call Espoma at 1-888-Espoma-1 or check out the Holly-tone site. Holly-tone is a product designed for all your acid loving plants.  Read the instructions on the box carefully.

If you want pink blooms, use less acidic fertilizer. Some lime lightly applied may be OK. Be careful to not make the soil too alkaline because that is not healthy for hydrangeas.

Two articles that also go into depth on the subject are this and this.

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