Using Superphosphate for Hydrangeas?

juliaroseOctober 13, 2007

Has anyone heard of using superphosphate for getting hydrangeas to bloom? It was recommended to me by one of our local nurseries, to do now and in January. I tested the soil by my oldest and largest hydrangea( that has not bloomed in 2 years), and it had adequate phosphate.

I have not seen phosphate recommended by any hydrangea sites.

I think it would have bloomed except we had a very warm week, when I uncovered it, and then we had two weeks of temps in the teens at night, which ruined fruit crops and other things around here. Unfortunately, my "Endless Summer" and "Now and Forever" hydrangeas (that are supposed to bloom on new wood) did not bloom either this year. I used acid fertilizer, but this did not seem to help. This is Bayer brand fertilizer, that states to use twice a year, in late spring and late fall. I am hesitant to do anything right now due to conflicting information. I do have 6 hydrangeas that are still alive.

Thank you for reporting this comment. Undo

Superphosphate does encourage blooming, but it is seldom required as phosphorus moves through soil extremely slowly and is most often present in sufficient concentrations. Too much phosphate creates a toxicity in a number of plants, so I'd be reluctant to overuse this product. Also, superphosphate is manufactured from a chemical reaction of rock phosphate and sulfuric acid and therefore tends to "sweeten" soils. Mophead hydrangeas treated to superphosphate will tend to bloom in the pinks and purples rather than blue.

I am letting in my personal bias here, but I tend to shy away from any kind of chemical-based or synthetic fertilizer or soil amendment. They are harmful to soil organisms, too easy to overdo, leach into groundwater too freely and even moderate applications can create nutrient imbalances, salts build-up and potential root burning (superphosphate is very inclined in this last regard). Applying a complete blended organic fertilizer can supply needed nutrients, however most plants - hydrangeas included - are well served by just periodic mulching with a quality compost, nothing more.

Lack of flowering with hydrangeas is generally not associated with insufficient fertilizing. Rather, it is most often caused by cold weather that damages flower buds, improper pruning or unnecessary fertilizing with a high nitrogen fertilizer.

    Bookmark   October 13, 2007 at 12:00PM
Thank you for reporting this comment. Undo

Thanks for your info. I would prefer more natural sources of fertilizer as well. I just added some dried blood to many of my flowerbeds, including the hydrangeas, because when I tested the soil, it was deficient in nitrogen.
As far as color, I actually prefer the pinks and purples, so that does not worry me.

As far as blooming, I am going to try one of the tenting methods to protect the new buds over the winter, or the method where you put something heavy on the plant and cover it with cardboard and mulch. My biggest plant is far too bid to cover with a pot, like I tried last year.

You are fortunate to live in a climate where you can easily grow hydrangeas and not lose the old wood! I am envious.


    Bookmark   October 17, 2007 at 10:33AM
Sign Up to comment
More Discussions
Invincibelle� Spirit II Hydrangea arborescens
Does anyone know if the new Invincebelle Spirit Hydrangeas...
Nikko Blue size
I planted a tiny bare root stick of a Nikko Blue Last...
Deer resistant hydrangea?
Hello! I am looking to replace some shrubs this spring...
DEEP blue
When I was growing up my grandmother had big vigorous...
Hydrangea Annabelle - Will it grow in Florida?
I fell in love with Hydrangea Annabelle when I was...
Sponsored Products
Eastwood Leather Sofa - Brighton Breeze Green
Joybird Furniture
Brescia� Control Brushed Nickel Energy Star Ceiling Fan Body
$339.00 | Bellacor
St. Moritz Entry Light by Corbett Lighting
$1,630.00 | Lumens
Deck Dining Side Chair in Silver
$114.00 | LexMod
Irene Rug 5' x 8'
$599.00 | Horchow
Hampton Bay Wall Mounted Cambridge Collection 1-Light Outdoor Essex Bronze
$59.97 | Home Depot
Borgonovo Hermetic 145-oz Jars (Pack of 6)
Medium 6 ft. Premier Micro Suede Fuf Foam Bean Bag Sofa - 0000078L
$289.98 | Hayneedle
People viewed this after searching for:
© 2015 Houzz Inc. Houzz® The new way to design your home™