If you over-fertilize, it can burn the root system of your hydrangea bushes and actually inhibit bloom production. For more tips on fertilizer and how to achieve big, beautiful blooms, please click here. My hydrangeas have brown dry spots on the leaves and brown petals on the bloom.
For hydrangeas planted in ground.
For optimal growth, bloom production, and quality, fertilize three times: In early spring when plants are just leafing out. In early May to boost their flower production for summer. In late June/early July to help your plants finish the summer strong.
Miracle-Gro Performance Organics Blooms Nutrition
This is an all-purpose blossom booster that's suitable for use on a wide variety of perennial and annual blooming plants, including hydrangeas.
Yes, over fertilized plants can recover with proper care. To help them recover, you should flush the soil with water to remove excess nutrients. Adjusting the watering schedule and providing adequate sunlight can also aid in the recovery process.
Yellow or Brown Leaves
When a hydrangea has been overwatered, one of the most obvious signs is yellow or brown mushy leaves. Touch your hydrangea's leaves just to make sure – dry leaves can be a sign of underwatering, so feeling them will help you tell the difference.
Water at a rate of 1 inch per week throughout the growing season. Deeply water 3 times a week to encourage root growth. Bigleaf and smooth hydrangeas require more water, but all varieties benefit from consistent moisture.
To help Hydrangeas thrive, give plants a deep soak 1-3 times a week rather than giving them little sips of water daily. Hydrangeas do not tolerate overwatering or drought well. Their leaves wilt in the heat of midday, making it difficult to tell by appearance whether they need additional water or not.
Rinse the soil with water.
Next, use a garden hose or sprinkler to flush the soil. Aim to apply about 1 inch of water each day for 4 to 7 days in a row. This will help to dissolve the salts in the fertilizer and remove any buildup of excess fertilizer in the soil.
Too many soluble salts causes leaves to wilt and yellow, leaf margins and tips to turn brown, defoliation and slow or no growth. Too much fertilizing also causes plant stress and weakens them, making them susceptible to diseases and insect attacks, particularly sap- feeding insects.
The best way to solve the problem of over-fertilization is to leach excess nutrients from the soil by using watering to slowly flush out the pot. (Your pot will need drainage holes for this.)
Balanced granular fertilizers such as Espoma Rose Tone and Holly Tone are good choices. Jobes Fertilizer Spikes are another good option. Avoid using fast-release fertilizers in liquid form on hydrangeas. These products can stimulate growth in the short term but may not sustain the plant for the long haul.
Also, when you do water, after a week or 10 days, water with a water soluble fertilizer such as Miracle Grow, Rapid Grow or Peters 20-20-20. Apply this water soluble fertilizer every second or third watering and see if the plant doesn't do better.
Water your hydrangeas in the morning before the heat of the sun is strong enough to quickly evaporate soil moisture. Try to avoid watering at night, which can encourage mold and mildew as the moisture sits through the cool night. Water your hydrangeas through the growing season as well as in late fall.
Supply the Right Amount of Water. Along with planting them in the right place, properly watering your hydrangeas is essential to bigger and better blooms. "Hydrangeas should be watered deeply several times per week to encourage deep root growth," says Enfield.
The same nutrients that make your lawn green and healthy -- nitrogen, phosphorus, and potassium -- can hurt your lawn if you apply too much. Too much fertilizer adds too much nitrogen and salt to the soil. It's called fertilizer “burn,” and can actually kill your lawn.
Nutrient pollution is the process where too many nutrients, mainly nitrogen and phosphorus, are added to bodies of water and can act like fertilizer, causing excessive growth of algae. Nutrients can run off of land in urban areas where lawn and garden fertilizers are used.
If your plant leaves' color is alright, but they are becoming out of shape or deformed, stop using miracle gro on them. The deformation of leaves occurs when you are using too much miracle-gro on them. Weakened plants from either the stems or the roots are a sign of overdosing fertilizers.
The fertilizer and soil should be thoroughly moist, but don't water so much that the water begins to form puddles.
Fertilizer and Water
A day or two before applying fertilizer, water your lawn thoroughly. After grass dries, apply fertilizer. Then lightly water again. This second watering is vitally important, because it washes fertilizer off grass blades and into soil.
Potted hydrangeas overwinter best in a garage or basement where the temperature stays cool but doesn't freeze. The plants will go dormant, but you'll still need to water the pots occasionally, about once a month, to keep the roots moist, until spring.
Most hydrangeas prefer only morning sun. Yet one type of hydrangea can soak up the sun all day: the panicle hydrangea. While they can stand the sun, these do just fine in partial shade, too. Plus, panicle hydrangeas are the hardiest hydrangeas.
In warmer areas, many hydrangea types will suffer in the afternoon's scorching sun. The leaves and flower heads may burn, turning brown. If you notice this, that means your hydrangea is getting too much sun. Try moving it into filtered shade, or an area where it gets only a few hours of morning sun.