Varieties of plants are in most cases more delicate than those that grow in the wild. And today’s plant is no exception.
Lack of watering, lack of phosphorus, or disease are reasons why Summer Crush leaves turn brown. To fix this, water the hydrangea when the top layer of soil is 1-2 inches dry and fertilize it twice a year with a multi-purpose fertilizer. Also, spray the leaves with fungicide for diseases.

Sunburn and overfertilization
Underwatering
Too dry soil is often the reason why the leaf edge turns brown. If the weather is not sunny, the leaves will droop from lack of water, but if the sun is bright, the edge can become crisp.
Shrubs that have been growing in the same place for several years are less susceptible to damage from lack of water. Newly planted plants are most sensitive to dehydration.
To prevent this from happening you need to water this wonderful hydrangea properly. Ignore the advice to water according to a schedule because you may overwater the soil and root rot will occur.
Only water Summer Crush when the soil is about 1 inch dry at the top. To do this, you need to check the soil moisture from time to time. Water with at least 1 to 2 gallons of water so that the soil is well saturated.
Sunburn
Although Summer Crush tolerates direct sun better than similar hydrangeas, it can still suffer from it. Young plants that have been in the same location for no more than two years are most likely to suffer from excessive direct sun.
If Summer Crush is exposed to the direct sun all day, it will definitely get sunburn and turn brown. Depending on the intensity of the sun, brown spots can appear on the leaves, or the entire leaf can turn brown and fall off.
In zones 5-6, Summer Crush can tolerate six hours of direct sun, as long as you keep it out of the afternoon sun. The further south it is, the less sun it needs. In zones 8-9 it needs no more than 4 hours of sunlight, the rest of the time it should be in the shade.
Also, in addition to the scorching sun, the leaves can turn brown from dry air. In this case, the edge of the leaf will turn brown first. To avoid this, choose a slightly moist and cool place for planting.
Not enough phosphorus
Too much fertilizer application can cause damage to the root system and consequently turn the leaves brown. The same result will occur if the recommended amount of fertilizer is exceeded.
The first thing you need to do is to wash the excess fertilizer from the soil. To do this, water Summer Crush several times with plenty of water. Let the soil dry out slightly between waterings.
Next, do not fertilize the hydrangea more than twice a year. Fertilize the first time in spring and the second time after flowering. Do not fertilize in autumn and winter because this can cause damage.
Also, the leaves can turn dark brown or almost black as a result of a lack of phosphorus. Often gardeners acidify the soil to change the color of the hydrangea, but in acidic soil, phosphorus is not absorbed by the plant. As a result, the leaves turn darker.
To avoid this, keep the soil neutral or slightly alkaline. This will give you red color and no leaf problems. Also, always use a fertilizer with phosphorus.
Pests and diseases
Diseases such as leaf spot can turn the leaves brown. At first, small dark brown spots appear on the leaf, and when they become more numerous, the leaf turns completely brown.
Many pathogens cause this disease so the best way to cure Hydrangea is to spray it with fungicide. Spray the first time with a multi-purpose fungicide, the second time use a copper fungicide.
Leaves can also turn brown due to bacterial disease. These are hard to treat, the best thing you can do is not to overwater your hydrangea. Also, make sure it has good air circulation and plenty of sunshine.
Sucking pests can damage the leaves so that they change color. Spider mites should be singled out here; they can form large colonies under the leaves. The foliage will turn pale at first and then turn brown.
To get rid of this pest, spray the bush with an aqueous solution of neem oil. If this does not help, use acaricide.
Summer Crush Hydrangea Flowers Turning Brown
The first reason the flowers turn brown is natural aging. After the hydrangea inflorescences have finished blooming, they begin to wither and shrivel. This causes the flowers to dry out and turn brown.
This can happen twice a year since this variety blooms twice. The first time in summer and the second time in early fall. This is a normal process and you don’t have to do anything about it except removing the dry flower heads.
The second reason for the browning of the flowers is too much sun. If Summer Crush gets more than 6 hours of direct sun, the flowers can get burnt. In the south, this can happen even if the sun is more than 4 hours.
To remedy this, protect the hydrangea from the scorching sun. In the fall or spring, transplant it to a location with fewer sun hours.