Did you have any freezing cold weather prior to this problem with the leaves? That is, did the plants break dormancy just before some cold weather hit and now the leaves show some winter damage? How has the weather been over there lately, hydrangeanut2009? Wet, dry, etc? If you insert a finger near the rootball, does it feel wet, moist or dry? It should feel moist. Wet is ok only if it recently rained or you just watered. Have you recently sprayed any insecticides that could have drifted into these hydrangeas? You may have some insects causing problems too but you should be able to check the affected and unaffected leaves during the day and at night. There are other fungal infections that could cause black leaves but I am hoping it is just winter damage. Luis

I am thinking that water your collect from your roof is on the acid side - too many cars, too much exhaust... we are not in a pristine world anymore... and the smoke from Chinese still mills is reaching Pacific coast of North America 24/7. My understanding is that AVs prefer the pH of 6.4-6.8, otherwise they do not absorb nutrients well enough. The second issue with rainwater - it doesn't have calcium and magnesium micronutrients that are always dissolved in a tap water. So oops. In some areas water is not good for tender plants - high Ph, high solids - usually it the water that comes from artesian wells. If the plant collection is large and watering it with a store bought Spring Water is too much, some people buy a RO filter that produces almost distilled water. For RO water Michigan State University developed a fertilizer that compensates for the missing micronutrients so you can get it. For now - repot your plants in a food fresh soil and try a bottled water for a while. Normally the tap water is OK, exceptions are dissolved solids over 200ppm, preferably around 150 ppm, normal tap Ph is around 8-8.5 - they add buffer - something Ca ang Ma salts to prevent sedimentation in the pipes. Usually it is compensated by the peat in your soil that produces humic acid if kept warm and humid... like in our houses. The last exception is if your water treatment plant uses chloramine instead of chlorine. Chlorine in water evaporates if you keep the water in the open for 24 hours. chloramine not so. You can neutralize it with chemical from an aquarium supply store. All this info you can get in your water treatment facility. They should send you a yearly report anyway.

If the leaves originally leafed out looking this way then there was some type of winter injury. If the leaves originally looked fine and turned this way, I would look for explanations like late frosts, insects/pests (mites, hydrangea leaftier larva or the leafroller insect), use of chemicals nearby, etc.

When leaf tips or margins abnormally curl/cup upward, it's usually an indication the plant is trying to retain moisture – most common causes are dry soils or high temps; or, if you are using supplemental lighting, the lights might be too close. When leaf margins curl down, especially if leaves droop abnormally from the base of the leaf to the leaf tip, there is probably an issue affecting root function or health. The main causal suspects would be over-watering or soil compaction causing an inadequate supply of oxygen to roots, a root infection, or a TDS (fertility) level too high, which can limit water uptake. As grow media comprised of peat and/or pine bark drys down, it eventually becomes so dry it repels water (becomes hydrophobic). As the soil mass dries, it also tends to shrink away from the walls of the container/ So you end up with a soil that repels water and a pathway between the soil mass and pot wall by which the soil can flow straight to the drain hole with only a small fraction of the medium absorbing any water at all. I would make this first on the list of things to explore as causal. The fix is to soak the pot in a tub for an hour or so until the soil mass is rewetted and the tendency toward hydrophobia is 'broken'. Once you've done that, water before the soil becomes that dry. Using a 'tell' makes it easy to determine when it's appropriate to withhold water or to water. Using a 'tell' Over-watering saps vitality and is one of the most common plant assassins, so learning to avoid it is worth the small effort. Plants make and store their own energy source – photosynthate - (sugar/glucose). Functioning roots need energy to drive their metabolic processes, and in order to get it, they use oxygen to burn (oxidize) their food. From this, we can see that terrestrial plants need plenty of air (oxygen) in the soil to drive root function. Many off-the-shelf soils hold too much water and not enough air to support the kind of root health most growers would like to see; and, a healthy root system is a prerequisite to a healthy plant. Watering in small sips leads to avoid over-watering leads to a residual build-up of dissolved solids (salts) in the soil from tapwater and fertilizer solutions, which limits a plant's ability to absorb water – so watering in sips simply moves us to the other horn of a dilemma. It creates another problem that requires resolution. Better, would be to simply adopt a soil that drains well enough to allow watering to beyond the saturation point, so we're flushing the soil of accumulating dissolved solids whenever we water; this, w/o the plant being forced to pay a tax in the form of reduced vitality, due to prolong periods of soil saturation. Sometimes, though, that's not a course we can immediately steer, which makes controlling how often we water a very important factor. In many cases, we can judge whether or not a planting needs watering by hefting the pot. This is especially true if the pot is made from light material, like plastic, but doesn't work (as) well when the pot is made from heavier material, like clay, or when the size/weight of the pot precludes grabbing it with one hand to judge its weight and gauge the need for water. Fingers stuck an inch or two into the soil work ok for shallow pots, but not for deep pots. Deep pots might have 3 or more inches of soil that feels totally dry, while the lower several inches of the soil is 100% saturated. Obviously, the lack of oxygen in the root zone situation can wreak havoc with root health and cause the loss of a very notable measure of your plant's potential. Inexpensive watering meters don't even measure moisture levels, they measure electrical conductivity. Clean the tip and insert it into a cup of distilled water and witness the fact it reads 'DRY'. One of the most reliable methods of checking a planting's need for water is using a 'tell'. You can use a bamboo skewer in a pinch, but a wooden dowel rod of about 5/16” (75-85mm) would work better. They usually come 48” (120cm) long and can usually be cut in half and serve as a pair. Sharpen all 4 ends in a pencil sharpener and slightly blunt the tip so it's about the diameter of the head on a straight pin. Push the wooden tell deep into the soil. Don't worry, it won't harm the root system. If the plant is quite root-bound, you might need to try several places until you find one where you can push it all the way to the pot's bottom. Leave it a few seconds, then withdraw it and inspect the tip for moisture. For most plantings, withhold water until the tell comes out dry or nearly so. If you see signs of wilting, adjust the interval between waterings so drought stress isn't a recurring issue. Al