I can never tell if I'm over or under watering. My snap dragons have very limp flaccid floppy leaves. There are no brown crusty leaf edges. The surface of the soil is bone dry but lower down it seems a bit moister but no-where near waterlogged. I put a reasonable quantity of water-retaining grannules in at planting stage. The soil is new - no evidence of pests or diseases. Can't remember when I last watered, maybe a few days ago. So, do the limp leaves mean I need to water or not?
They don't look too bad to me - lovely and green anyway! Most plants will wilt a bit in the kind of heat we're currently getting, then pick up again in the evening.
If it doesn't look like it's going to collapse imminently, I'd wait and then give it a water this evening. Watering in the heat of the day can give you leaf scorch issues, and most of the stuff you dump on just evaporates off the soil. At least it has more of a chance to sink in if done later on.
Maybe think about getting a mulch on the soil underneath - a thick covering of cheapo compost will do. It'll help to lock moisture into the soil for just a bit longer.
When you check for moisture how far down in the soil do you look? The photo does look deceptively green but if you touch the leaves they're limp as hell. It's sulking, I'm just not sure why? It is in a container & maybe the drainage isn't good enough?
Ahhh, it's in a container! If you haven't watered it for several days, then I doubt overwatering is the problem. I think it's suffering water stress because of the heat. Can you move it to a shadier spot, or is it just too heavy? (Don't do yourself a damage!!)
It will perk up once it gets some water later on. Most of my garden (in soil) is looking a bit limp right now.
I normally water pots every day in hot weather like this, sometimes even doing morning and evening (e.g. in the greenhouse). They seem to need it even when they've got drought-tolerant plants in them. If it's really dry, you may need to stand the pot in some water for a bit to get the compost/soil to rehydrate, otherwise the water may just bead and fall off the pot instead of going in.