Do you happen to know the name of this hydrangea variety? The plant label usually gives the names.

Some hydrangeas that are sold with generic names are not winter hardy in some areas and the flower buds that the plant produces in July-August die during the winter months. The stems also die sometimes and then new growth restarts from the base or crown. But that new growth does not usually produce blooms right away. It produces invisible flower buds in July-August and these will open in Spring of the next year (assuming that the flower buds and stems do not die off). Knowing the name of this hydrangea will help determine if it is winter hardy.

Miracle Gro has a bunch of "basic" ones. The oine called All Purpose Plant Food has a lot of nitrogen (almost 30%) and this could be causing problems as well. The levels of nitrogen slowly increase to the point where the plant has so much nitrogen in the potting mix that it stays in "growth mode" during the Fall when it should be going dormant instead. It also tends to produce nice lush green leaves at the expense of blooms.

You can probably tell for sure if you are accumulating a lot of nitrogen in the soil because they sell some kits that will tell you if your soil has too much or too little nitrogen. If you can find one and test the soil, you could determine if the fertilizer is causing problems or not. If not, the variety may not be hardy.

You can tell if the variety is hardy or not from the plant label. Providing the shrub with winter protection in the Fall may be the answer although it is definitely hard when the plant is in whiskey barrels.

See if you can find the name of the hydrangea from the label and its winter hardiness information.

Grab a buddy each Fall, and haul the plants down to a garage, shed, or low-lying area against a foundation wall for the Winter. Keep soil most and do not allow roots to freeze. If that still doesn't work, you can switch to something with a better rep like F&E White Out, but you should still treat them in the same fashion.

Hi and thanks for your input. From what it looks like, maybe it is that Miracle Gro I have been using:/ It's not the bloom booster one, but the plain one. The card that came with the plant simply says "Snowball Hydrangea-White, Hortensia-White". The sticker was placed over "Blue Danube Hydrangea".

Try using the MiracleGro formulation for acid loving plants - that should keep the hydrangea happy as well as promoting flowering. Also, Spingwood's suggestion to move or otherwise offer winter protection for these plants is extremely valid. Most mophead (or "snowball") hydrangeas bloom on the previous season's growth and this is easily damaged by winter cold. In zones 6 and below, winter protection for these types of hydrangeas to ensure proper flowering is highly recommended.