Summer Crush develops two flushes of blooms, one in spring and another in late summer/fall. Being a hydrangea macrophylla/Big Leaf Hydrangea, it prefers morning sun only but can encroach into the afternoon hours if your summers are not harsh and it can get supplemental watering. Because the shrubs' leaves do not display symptoms of complete leaf yellowing or leaf browning from the edges inwards, it appears that although its sun exposure is unusual (plant 1 gets afternoon sun), it is not harmful (at least so far this summer) and they are sufficiently hydrated.
Bloom failure in the spring can be common and those cases, last year's stems do not leaf out and all growth in spring originates from new stems. Typical causes for this: oil nutrient deficiencies/toxicities (a nitrogen, potassium, phosphorus soil test kit can help determine if the soil is deficient or if the grass is eating nutrients from the equally shallow rooted hydrangea); fertilizing after the 2nd-3rd weeks of July so the flower buds get killed by early frosts; fertilizing early before the 1st-2nd weeks of May so the flower buds get killed by late frosts; over-fertilizing with high nitrogen content fertilizers (only use general purpose, slow-release fertilizers with a NPK Ratio of about 10-10-10 and keep lawn fertilizers away from the plant); reduced vigor from last year's diseases (powdery mildew) may cause less or no blooms; pests like deer, rabbits and squirrels may eat the flower buds; dense shade may reduce flower bud development vigor; insufficient watering in winter may dry out the soil too much and cause the plant to abort the spring 2023 flower buds (water until the soil freezes but at reduced levels; water when above freezing if the soil is dry in spots under the canopy area at a depth of 4").
Bloom failure for late summer/fall 2023 is too early to diagnose as summer just started. To produce a second flush of blooms in late summer/fall or earlier, the new spring stems have to get tall and old enough, quickly enough to bud and bloom by late summer/fall 2023 or earlier. Summer Crush can get 3 feet tall or more so a sufficient height and a good environment should trigger budding and blooming. But wait until high summer temperatures recede to see the blooms of the second flush; even roses diminish or stop blooming when hot. Maintaining 3-4" of organic mulch around the shrub in a 4 feet circle should help keep the grass away (you could also add a green metal barrier 2-3 feet away from the hydrangea's crown/base of stems); should protect the roots from hot/cold temperature extremes and should provide nourishment as the mulch decays and is replaced. The soil at a depth of 4" (typical hydrangea root depth) should be kept evenly moist during the summer, not dry nor wet. Use enough water: after allowing the water to percolate, the soil at a depth of 8" should feel moist if you used enough water (if the soil is dry, use more water; if the soil is wet, water less).
There is some Cercospora Leaf Spot in some of the leaves, a fungal disease. It Is usually promoted by either a normally very humid local environment, by over-watering the soil and-or by directly watering the leaves. Fungal spores for this disease exist in most locations world-wide so this problem is very common; it tends to become visible only after the Summer Solstice –though not exclusively- when chlorophyll production tappers off. Scattered, small, somewhat circular orange, brown or purple spots first appear on leaves near the base of the plant. The spots are usually about one-eighth to one-fourth inch in diameter and grow larger as the disease ages/spreads up the canopy. It becomes visible either in summer or fall but can occur in spring. Heavily spotted leaves turn yellow green or yellow and may fall to the ground, helping spread the spores.
While Cercospora leaf spot rarely, if ever, kills the target plant, heavy spotting of the leaves and premature leaf shed is unsightly and may reduce plant vigor and flower bud set for next year in old wood hydrangea cultivars. Therefore, in the following year, less blooms or smaller blooms might occur if the problem is not quickly addressed. Fallen diseased leaves and foliage that rubs the soil are the primary source of spores of the fungus. These spores are spread to the healthy lower leaves by splashing water. Once the fungus is introduced into a planting of hydrangea, yearly outbreaks of this disease are likely to occur. Fungicides do not cure the infestation but help control it, especially if they are applied starting in the spring, before symptoms are visible (spray as soon as there is leaf out or new stem growth). Frequent late summer rain showers will not only greatly increase the rate of disease spread, but also intensify the level of leaf spotting and defoliation. On the other hand, extended periods of heat/drought will usually suppress disease development and spread.
To help slow disease development and spread, remove the worst of the diseased leaves (green leaves are still producing food for the roots); apply just enough nitrogen to maintain a moderate growth rate; and water the soil, never the leaves. Since the appearance of symptoms is usually delayed until late summer to early fall (when foliage is ready to fall as the plants enter dormancy, protective fungicide sprays are rarely needed for the control of this disease on hydrangea in the landscape. Clean sanitation practices should help control the problem greatly: remove all forms of plant debris (deadhead any blooms in the fall; cut the string that attaches all leaves to the stems, etc.) at all times, especially when the plant goes dormant; discard plant debris in the trash; do not water over-head (use soaker hoses or drip irrigation) but water the soil instead; if using a sprinkler system, activate the station that waters the hydrangea around 6-8am so the foliage will not spend a lot of time wet; improve air flow inside and around the plant; replace the mulch with new mulch; increase the amount of direct sun that the plant receives if it is practical; use fungicides cleared for treating Cercospora Leaf Spot; etc.
Fungicides should only be a part of an overall disease management program that includes the previously mentioned clean sanitation practices. For effective control of Cercospora leaf spot with a fungicide, begin applications when spotting of the leaves is first seen and continue applying per product directions. Next year, start spraying in the spring after leaf out or new stem growth.
Fungicides registered for the control of Cercospora leaf spot include the following (the fungicide's active ingredient is listed first and some commercial product names follow in parenthesis): azoxystrobin (Heritage; has the smallest application rate and the largest repeat interval); chlorothalonil (Bonide, Daconil); copper hydroxide, copper octanoate/copper soap (Kocide, Bonide Liquid Copper, etc.); mancozeb (Dithane; Protect; other names); myclobutanil (Immunox); thiophanate-methyl (Cleary's 3336).
