Hydrangeas

July is here and that means water, water, water your garden.  We have had some good rain in past weeks, but with the heat steady coming on and no rain to speak of in the last four weeks you will still need to water.  Plants need a good inch to inch and a half of water a week.  Containers will need more than that in the extreme heat, probably at least once a day if not twice a day.  The shade garden will also need that extra drink of water because plants will be competing with trees for water and nutrients. 

Hydrangeas are fussy plants this time of year due to extreme heat.  Do I water or do I not water? The hydrangeas are wilted when I get home, but in the morning they look normal.  Hydrangeas need water, but not too much water.  They require well drained soil and about six hours of sunlight.  If you give them too much water it will encourage disease.  They are prone to root rot and fusarium wilt when they get and keep wet feet, so before you plant your hydrangeas, amend the soil to help with drainage. Root rot is exactly what it sounds like, the root system get soaked for extended periods of time and rots away.  Fusarium wilt is a soil born pathogen and develops a fungus which clogs up the vascular system of the plant and keeps it being able to take up water.  The leaves will start to yellow and wilt from both of these conditions and make you think they need water when they don’t.  There is no real cure when they get to this point, except to shovel prune them.  Hydrangeas are also susceptible to leaf spot, blights, and powdery mildew.  These problems are best controlled also by water management along with well drained soil.  A good fungicide can also help with these.  I would recommend daconil combined with mancozeb.  After speaking with a plant pathologist friend today, he recommends that a systemic fungicide containing the active ingredient propiconazole.  I have observed these problems in my own landscape.  I have lost a couple of my hydrangeas, but managed to correct the problem and salvage the rest of them.  This problem also affected the homestead verbena and we lost a good sized area of that too.  I have always been content not to prune hydrangeas except to get flowers for drying.  A good friend who is a gardener’s gardener, laughingly told me that is why the ones up next to the door bloom so profusely.  He says to prune them when the blooms start to fade and this will promote new growth which will give more blooms.  He did agree that you should not prune the ones that bloom on old wood after the end of July as they start setting their new flowering buds at this time.   

Despite all this about disease, hydrangeas are relatively easy to grow.  Prepare the planting site by adding at least half again organic matter and you should have years of enjoyment from your hydrangea plant. Fertilize them in March, May, and July with a good general purpose fertilizer such as 8-8-8, 10-10-10, or13-13-13.  Be careful not to add nitrogen rich fertilizer as this could keep them from producing blooms.  Water in the morning and preferably use a drip system as opposed to watering overhead.

If you have any questions or comments, send me an email at colorsbytim@hotmail.com or leave me a message at the Union County Extension Office at 662-534-1916.  You can also find me on Facebook, mastergardner, and Saturday mornings from 8:00AM to 9:00AM on WNAU Radio 1470 on the radio dial or listen online at www.wnau1470.com 

Happy Gardening and Keep Digging in the Dirt.