[andtiggertoo]

what would be the smallest water container that frogs would be happy in.

I'm not really into water features but I would like a lot of frogs to eat the slugs and pests in my garden.

Thanks
 

[agapanthus]

One of our cats brought in a toad the other day and it survived. I put it in the greenhouse and buried a sink (complete with plug) next to some rocks and straw,,,seems to be ok with it!!

[andtiggertoo]

hi agapanthus i was already kicking myself for letting my kitchen fitters take my old pot sink away. Almost as soon as they took it I thought i could have used it in the garden. It might have been ok as a little frog pool !

Maybe someone knowledgeable about frogs and ponds could tell me if frogs & spawn can survive in water less than about a foot when we have sub zero temperature. Also will the water go green if there are only frogs and water in it, and no soil ?

I thought about experimenting with a large plastic tub sunk into the ground about half
way. But I don't want to do anything that would be cruel to the poor critters, assuming I can find some frog spawn to put in it of course.

Think I need to read up on frogs a bit before I pursue this project !!

[Hortic]

There's a lot of info on line about putting a pond in. A good start is the Freshwater Habitats Trust and your local Wildlife Trust.
DO NOT PUT FISH IN. If you want fish, make a separate pond. Look for native pond plants growers, some offer starter packs. This will depend on the size of your pond. The grower websites usually have advice links. Be patient and don't over plant. Things will grow and fill the pond.
Don't use upturned grass sods as edging. This will regrow and give you problems. More importantly, rain will cause nutrients to leach into the water and cause algal blooms. You don't want this. Look out or advertise for large stones and rocks to secure the edges. 
I'll try and attach a photo of my allotment  pond when it  was first built.

[Subversive_plot]

what would be the smallest water container that frogs would be happy in.

I'm not really into water features but I would like a lot of frogs to eat the slugs and pests in my garden.

Thanks
 

Toads would be better candidates for eating the pests in your garden.  They are better-adapted to being OK, even if their "pond" dries up for a day or two, or even longer.  They lay eggs (spawn) in ponds or puddles that last for a few months during the wet spring, but are OK if that pond/puddle is an intermittent feature.  The feature only has to stay wet until the tadpoles grow both sets of legs and their tails start shrinking, then they start migrating away from the pond/puddle.

If you see "frog" spawn in the wild, in puddles away from a permanent pond, those will almost always be toads.

Whatever water feature you set up should have at least one gradual slope out so the little beasties can climb out.  You can buy rigid pre-formed plastic liners, or get flexible liner material.  For toads, a recirculating pump and aeration system is probably not necessary (they don't have that in nature).  You probably do want some stones in the bottom, as wading birds sometimes find such plastic-lined ponds and poke holes in the bottom, chasing fish or tadpoles. For the same reason, a bit of floating board will provide a little cover from birds that come hunting.

You might find that dragonflies are also attracted to your pond.  That's a good thing, as the dragonfly larvae eat mosquito larvae, and the adults eat adult mosquitoes.

Toads tend to winter over on land, even in cold climates. Picture something like a compost heap, with layered sticks and coarse leaves, and lots of air gaps and "pockets" to burrow into.  Perfect for toads.  This bit of reading should take away any fears you might have regarding toads and frogs dying due to the cold: https://spectrumlocalnews.com/nys/central-ny/blog/2021/04/06/the-frozen-hard-truth-about-frogs-during-the-winter  Spoiler alert: they can live through being frozen solid! A toad in the wild will find it's own shelter though; you could provide something, but they probably won't need it.