help how do I plant water plants?

My pond plants arrived today( had to buy from ebay), they have some roots i think but were sent just wrapped wet.
They are frogbit and Ceratophyllum demersum

What do I do with them now?

 

It depends.
I'm ignorant of the names of your plants and whether they are marginals or floaters whatever.

The only pond plants I had in my first two ponds were lilies and a few marginals. These were planted in ordinary pots, lilies in the big perforated baskets.
If they are going in pots you need to weight the bottom of the pot. I've always planted them in a mixture of compost and soil and given them a good soak before putting them in the pond. It's essential to put a thick layer of washed gravel on the top of the pot, otherwise as you put them a fair amount of the soil will float away making your nice clean pond water a dirty brown colour. Hold them in position until they stop bubbling otherwise there's a chance the pot will float away.

 

If you've only a few plants to plant then J. Arthur Bowes' aquatic compost is brilliant. None of the soil will disperse in the water.

If you've a load of plants to put in then yellow clay is perfect.

Any old container will do for the plants, although ones with holes in the sides are recommended. I use burger bun trays that I pick up from shops. Black is the best colour for your containers; they don't show up through the water then.

 

Thanks, I think I will have to use compost and soil because there is nowhere local that specialises in ponds and water plants etc. Will it be ok to just let them float loose in the water until I can get them planted?

 

I'd imagine they'd be fine floating around. They won't die anyway.

Personally I'd prefer to use soil without compost because a; it's cheaper but mostly b ; because compost will put too much nitrogen into the water: the less richer the soil, the better for immersing in water.

 

Both those plants will be ok without soil.

Frogbit is a floating plant (like a small lily) - these make buds that sink in the winter and pop up again in the spring. Although a floating plat this really took off in the shallower areas of my pond where the roots could get in to some mud/gravel.

Ceratophyllum demersum - Rigid Hornwort is a submerged oxygenator. Again I just chucked a few hand fulls in my pond and it has slowly put down roots in to what ever was on the bottom.

For my other marginals I just used garden soil with gravel on top. My water has been crystal clear since spring - but I do have loads of plants in there.