Help! what is destroying my beautiful zinnias?

Hello everyone, newbie gardener here, I've planted a flower bed by the walkway in front of my house this spring and at the front of the flower bed I have three zinnias. I live in central Texas (hill country). So the zinnias seemed like a good choice; love full sun and hot weather, are drought resistant, and also bloom frequently.

The only problem: in the last few weeks something has started to eat/destroy/massacre them. Have a look at the photos I'm attaching. I can't for the life of me figure out what it is. All the other plants in the bed are doing perfectly fine, but as you can see, the leaves on these zinnias are being eaten alive.

I assumed it was some kind of pest so I did a bit of research and got just your basic spray from Home Depot and sprayed them. Nothing changed. When I go look at them I can't actually see any live insects or pests, so I have no idea what I'm even dealing with.

Any advice would be greatly appreciated---I'm at my wits' end. Please help me save these beautiful plants!

My first guess (especially the first picture) was that they got too hot too fast, for example if you were having a heat wave right after you planted them. Young plants are grown in greenhouses, or under shade, so are not ready for the full sun right away.

Then I saw that you have already sprayed something, so I will back up and ask:

Are you asking about the brown leaves? This is more typical of sunburn, pesticide damage or salt in the soil, not an insect.
If the brown showed up before you sprayed, then maybe my first guess is right.
If the brown showed up after you sprayed, then it might be a response to the spray, and we have not found the pest, yet.

Try going out at night with a flashlight and see if you can find any pests. Many insects and other 'bugs' hide in the soil during the day, and eat at night.

So, you purchased plants ?

I suggest you purchase seeds, and
plant them directly in loosened soil.

Its more economical, you will get
more bang for your buck, and you
will know where they came from
& how they were treated.

Only use pesticide sprays as a last
resort.

What is near Scenic Oaks ?

It hasn't been as hot as normal this year.

Hi asjd, my advice for you and for future, NEVER buy, use or make stuff to spray on your plants unless you know what you have as a problem, there are as many sprays for all different types of bugs, moulds, pick-me-up's and slow me down's that for Hobby gardeners like us, your causing more problems than helping.

Best way to go is look or ask for home made spray's that are chemical free and very, very rarely harm any plants wildlife or kids. BUT again, find what your trying to treat, what your doing is like giving your kids medicine but don't know why or for what.

I agree with Diana that whatever you have sprayed has given you the dead / dying plants you have shown in the picture, IF I were you, I would remove them plants, refill the spot with another plant IF the empty space is too obvious.
Lifting the plant out the soil will give you a chance to have a better look at the soil, the plant, under the leaves and all other aspects that could have caused the problems you felt were needing sprayed.
Make sure that the plants are getting enough water, in very warm / hot weather, new tender plants cant settle into their new environment, AND fight a heat-wave, and grow / make flowers, that's way too much for them so it's up to us to try help them survive the new area we plant them in, doing this care might mean building a shelter, watering more often (stick your fingers into your soil beside the plants root area and if dry, give loads of water, if damp leave watering for next day) Never pour water onto the tender foliage as you can break up the firm texture of the leaf, just water the soil around the roots, in fact, in really hot weather you may have to do watering morning AND evening, I prefer to lay the hose down and leave the water running onto the soil for a good while, this waters deep down into the soil where it's required BUT again, it's by experience and common sense. that comes in time but ask yourself what a child need, baby plants are the same in my eye's,

Hope all this helps you out a bit as everyone has tried to give you best advice, so good luck
luck, hope your other plants pick up soon.
Kindest Regards.
WeeNel.

Having learned from experience as a relatively new gardener myself, just because a tag on a plant says "Drought Tolerant" doesn't means as soon as you plant it that it is drought tolerant.

When I first began really gardening 3 years ago, I thought "drought tolerant" meant watering after I planted it, and then only occasionally unless it rained. However, I was mistaken! Thankfully, the more experienced gardeners here explained to me that a drought tolerant plant must be established before it is considered drought tolerant. It made sense that the plants needed moist (not wet) soil in order for their roots to grow, rather than dry soil.

Last year was my first year growing zinnias. The first month or two, I watered once a week maybe. They just didn't grow very much. Brown leaf edges appeared and I assumed it was an insect or disease. However, in July, I began watering them deeply at least twice a week and what a difference it made! They doubled in size by August and no more brown leaf edges or dry, crumbly brown leaves at the bottom of the plants.

Another thing I have learned is that garden borders that are bricks, stone, or a sidewalk reflect the heat onto the plants. So, not only are the plants getting heat directly from the sun, but from the brick/stone border as well. In my case, and probably in most cases, that meant the plants needed watering more frequently...as least until established.

Also, the only pest I ever had on my zinnias were snails or slugs and their damage appeared as holes or near translucent holes in the leaves. To fix that problem, I just put a little snail & slug bait underneath the leaves at the bottom.

Hope your zinnias perk up soon! Good luck!