In article , MarkA MarkA.1w4ivz@garden
banter.co.uk writes


Yes I know it's tiny, but that's the point. Space is at a premium,
aesthetics is not a priority, it's probably only temporary, and it's an
experiment - a way of adding wildlife value to a tiny backyard (I've
seen frogs using a "pond" of comparable size, and it will be dug into
the ground, with the rim at ground level). If it doesn't work, it
doesn't work, but I'd rather find that out for myself.

Perhaps I should rephrase the question: must I use up valuable water
volume by planting in pots, or can I plant into a substrate at the
bottom, and if so, what should that substrate consist of?

You'll use more space by having a substrate - you'll take away depth.
You should use the special aquatic pots which are like plastic baskets.
they don't need to be large - you may be able to get away with 2 inches
square. Aquatic compost - low nutrient, too.

Some of the water weeds don't need soil as such - they just throw roots
into the water. Then you'll also want something to cover some of the
surface - you could use a floating plant.

If you want wildlife, then you'll be best sticking to UK natives. A lot
of plants will be too big or too vigorous. Watercress grows if you just
chuck a bundle in, but grows too quickly - you'll be forever weeding out
the surplus. Water forget-me-not is a good bet and again just throw in a
rooted cutting, also Mimulus (monkey musk). You won't need a lot of
plants.
--
Kay
"Do not insult the crocodile until you have crossed the river"