Using African Violet mix as ferts for Hydrangeas

[CatherineSA]

Hello all,

I've chosen to grow these flowers in homage to my grandmother, who adored Hydrangeas. My aim is to have them bloom during summer, over her birthday. I'm not fussy about the flower colour, but I am quite particular about the health of my plants and so I have set up spacious, well-draining pots filled with a peaty, humus-filled potting soil. (I haven't yet planted the Hydrangeas.)
On the advise of an assistant at our local nursery, I also purchased a bag of "African Violet mix" to use as fertilizer on the Hydrangeas. I've searched online and found no information about using African Violet mix on Hydrangeas. I'm afraid that I have no idea what is in the bag. I'm inclined to take the assistant's word for it, but I thought I would seek out some more advice.

Good idea or bad idea to use African Violet mix as a fertilizer for Hydrangeas?

[luis_pr]

Greetings from Texas, CatherineSA. Hydrangeas are not hungry plants like roses. In the ground, they can grow just fine with one or two applications of fertilizer (or manure, or compost or cottonseed meal) per year. However, because potting mixes loose their nutrients easily due to the frequent waterings, you will need to add some form of fertilizers regularly to replenish that which leeches out of the pot.

As to whether the african violet mix will work or not, maybe. There is a huge variability in african violet fertilizers when it comes to nitrogen, pottasium and phosphate content. And water soluble versions will drain the "good stuff" fast thru the pots' draining holes. If you can find a slow-release version where the NPK Ratio is 10-10-10 (or a multiple thereof), it should be fine. For example, a slow-release fertilizer with a NPK Ratio of 14-14-14, 14-12-14, or 20-20-20 would be fine. Unrated ones (those which provide no NPK Ratios) are difficult to assess; I am referring to some containing all natural ingredients such as coir, etc; I suggest you therefore stay away from those.

I also suggest a regular application of liquid seaweed or liquid fish as these contain lots of micronutrients/trace elements that need to be replenished as well.

[Kisal]

Luis, your posts always seem to teach me something new!

I would appreciate one point of clarification on the fertilizer recommendation for hydrangeas, though. I have grown African violets for many years, but this is my first year growing a hydrangea. I'm a total novice in regard to that species. I have always understood that flowering plants required a fertilizer with a higher phosphorous content, I.e. the middle number of the NPK label. Is that not the case with container-grown hydrangeas?

[luis_pr]

Hydrangeas are not heavy feeders like roses. Planted in the ground, I feed them twice a year only (for example). They also do not bloom as often as roses so unusually high concentrations of phosphorus are not needed. A slow-release fertilizer and frequent watering should be enough to keep them happy. If you want to add some, you could try more phosphorus on remontant varieties like Endless Summer but I normally do not feed plants "too much" fertilizer and amendments.

[Kisal]

Thank you, luis!

[luis_pr]

I guess I just "woke up", Kisal, because I now noticed the doggie picture. Lord oh Lord! Say hello.... good doggie! I have two dogs, a Golden Retriever Mix and a Border Collie Mix. A third one, a German Shepherd Mix, passed away last September. They keep me busy picking doggie hair clouds from the floor every day. My mother also has to walk with her hands at waist level because they will lick her hands if they smell breakfast/lunch/dinner/etc in her fingers. Hee hee hee! Funny looking.

[Kisal]

They keep me busy picking doggie hair clouds from the floor every day.

Judging by the amount of hair I sweep up off the floor every day, I'm always amazed that Angus (the Lab in my avatar) isn't totally bald!