Why can't i get my Hydrangea's to bloom???

I live in Orange County CA, and they get 1/2 day of sun. The leaves grow, and it starts to bloom, but then they just die.
Why can't i get my Hydrangea's to bloom???
Didn't you say that you have blooms but that they die? If that is true, then focusing on what prevents hydrangeas from blooming will not solve your problem as suggested by the previous 2 posts. We must instead look to probable causes of bloom blight or damage. Here are some reasonable possibilities:



BACTERIA BLIGHT

Bacterial wilt can blight (they just die) flower clusters. Leaves may be affected as well. This disease is worse after heavy rains and hot weather. If severe, wilting and root rot can occur, followed by plant death. The causal organism is Pseudomonas solanacearum, and no chemical control is available.



BOTRYIS

Botrytis (grey mold) also affects blooms, but this disease generally produces a grey mold, thus its common name. In fact, Botrytis on hydrangea is usually limited to the ?ower buds and especially the petals. The small water-soaked spots seen on the petals quickly expand into reddish brown irregular blotches. Brightly colored petals quickly fade to a brown, withered mass that can be covered with a fuzzy

grey growth. Botrytis blight could be the source of your frustration.



Fungicides will protect hydrangea from Botrytis blight only if used in combination with good management practices. Start treatments when the plant is beginning to bloom and continue until ?nished. Fungicides: Chipco GT, Dithane, Fore, Protect, or Halt.



Remove infected plant material %26amp; dispose. Remove plant litter. Do not overhead water. Clean pruning tools with 10% bleach or 75% alcohol solution between cuts.



THRIPS

Another possibility is the western flower thrip. These sap sucking insects can be in your hydrangea buds, damaging the blooms before they deploy. Thrips are difficult to control because they are in the flower buds.



Colorado State University Extension Service:



-Dislodge them by applying a strong stream of water to the affected plant. Larvae are wingless and will not find their way back to your plant. This is one time you will want to use overhead watering as it kills many of the thrips.



-Placing aluminum foil mulches under the plants has been found in some instances to disorient the thrips.



-Remove and discard affected blossoms and plant parts.



-Thrips prefer tender new growth. Avoid excess pruning which may stimulate new growth or applying high nitrogen fertilizers.



-Avoid planting near dry, weed or grassy areas. Thrips migrate from these areas into the garden.



-The location of the insects makes it difficult to reach them with insecticides. Products that have been somewhat successful are: horticultural oils, insecticidal soaps, Neem, pyrethroids, acephate (non-food crops only), Nicotine, Orthene and Trumpet.



Two biological controls have shown promise in Colorado. They are Beauvaria bassiana (Naruralis O, Botanigard) and Spinosad.



The MSU Dept. of Horticulture also has identified Spinosad as a low toxic %26amp; effective biological control of thrips. The product name is Conserve SC. "Conserve SC has a "moderate" spectrum of activity. It is most effective on chewing insects including beetles (particularly Chrysomelidae), caterpillars and sawfly larvae. Leafmining flies, fungus gnat and shore fly larvae are also potential target pests. It appears to have good activity on thrips and sporadic activity against mite species.



Hydrangeas are tolerant of a very wide pH range (4.5 - 8.0). Aluminum dissolves and is available as a micronutrient between a pH of 5.2 to 5.8. Aluminum has been identified as the micronutrient repsonsible for turning blooms blue on a Mop Head hydrangea. Aluminum is not responsible for the retention of hydrangea blooms. At a pH level of 5.0, availability of the macro-nutrients Nitrogen, Phosphorus, Potassium, Sulfur, Calcium, %26amp; Magnesium are significantly restricted and become a bigger issue for the plant's health than the availability of aluminum.
Reply:Your soil may have the wrong pH for the flower to take up enough aluminum to keep the bloom going. The pH should be about 5.0
Reply:Hi ~



Don't prune unless necessary. Pruning often removes the flower buds. If you need to prune, remove any dead stems in the spring. Any other necessary pruning should take place immediately after bloom. The new flower buds form in autumn, when night temperatures consistently drop below 60 degrees.



Cover the plants to a depth of at least 12-18 inches with mulch, bark, oak leaves, pine needles, or straw. Cover the entire plant, tips included, if possible. Remember not to use maple leaves because they will mat when wet and can suffocate the plant. Some people make cages out of snow fence or chicken wire to hold the mulch. One creative gentleman, who every year has a spectacular Hydrangea garden, uses 20 gallon plastic trash cans. He cuts off the bottoms, places them over his plants in early winter, fills them with mulch and then puts the lid on them until spring.



Remove the mulch only after any major threat of frost (50% frost-free date) has passed. Do not be concerned if there are small white leaves and stems they will survive and turn green again quickly.
Reply:Most plants that don't bloom can trace their problems to several sources: not enough light, deer damage, pruning at the wrong time, bud drop from extreme changes in temperature, or lack of proper nutrients. If your hydrangea bloomed regularly but stops blooming, look for changes in the growing conditions �� denser shade, less wind protection, or perhaps unusually harsh weather.



Some varieties don't bloom year after year. The Mophead (rounded) varieties are notorious for not blooming year after year.



There may be a general lack of Phosphorous in the soil, %26amp; too much Nitrogen may have caused a lot of leafy growth at the expense of blooms.



Or...sometimes hydrangea will leaf out early in the spring during a warm spell and then get caught in a late spring freeze. If the new growth came only from the ground, then types of hydrange that blooms only on old wood will not bloom this year.



The smooth hydrangea (Hydrangea arborescens), bloom on new wood so if you prune in late winter or early spring, you won't accidentally cut off this year's flowers. Others, like some mopheads and many big-leaf hydrangeas (H. macrophylla) bloom on old wood, so any late-season (or fall or winter) pruning you do erases next year's flowers.

You can prune a third of the stems of mophead hydrangeas (H. macrophylla) to the ground after blooming and cut off flower heads when they become tattered. But do not prune the flowerless straight shoots without side branches because these are the ones that will branch out and flower next year.



They are heavy feeders. To encourage flowering, use a fertilizer low in Nitrogen and with a Phosphorus content over 30. (An N-P-K ratio of 10-40-10 is ideal) %26amp; fertilize them regularly. Organic soil enriched with compost is best. If using store-bought fertilizers %26amp; you don't want to fuss with a scheduled feeding of fertilizer, you can also use a slow-release fertilizer like osmacote or use manure around your plants. Water on a regular basis.



Usually too much shade will also retard the development of flowers, %26amp; full sun can scorch the leaves so part sun to shade is best, but you seem to have enough sun. Morning sun and afternoon shade is ideal. Are your Hydrangeas planted planted in an area away from drying winter winds?



Here's a site on How to prune Hydrangea:

http://www.hydrangeashydrangeas.com/prun...

Good luck! Hope this helped.
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