New wildlife pond

Collareddove

This winter we had a new wildlife pond dug. It is roughly oval, 9ft long,  5ft wide, approx depth in middle is 2ft, with sloping sides and 'shallow end' for wildlife to exit. We have lined it with fairly flexible plastic, not, alas, butyl.
Over winter the pond has virtually filled with rainwater channelled into it from a rainwater butt.  Now wondering what to put in the bottom  as the medium for deep water pond plants?  Quite a few leaves have blown into the pond and sunk to the bottom.  Next year we will cover against leaves, but this year should they be removed, or can they remain mixed with whatever medium we use?

Fairygirl

It would depend just how much is in there. It's normal for some material to get into ponds though. 
Most people tend to use pots for their plants. Are you not doing that - are you wanting to plant directly into a base layer ?  That can be more difficult, especially initially. You'd want a fairly low nutrient medium to start with. It'll take a while for that bottom layer to settle and be viable for plants though. 

Collareddove

I do intend using potted plants, but hoping to place them onto a base layer, so they eventu ally root into that layer.  Otherwise, how do you deal with the plants when they outgrow their pots? Do you have to yank them out of the pond and re-pot them before replacing in the pond?

Fairygirl

In a word - yes 
Over time, you can drop pieces of divided plants, or new plants, directly into ponds too. You'd need to weight them if they're small, so that they stay in contact with any matter at the bottom. Many plants also self seed. 

Many waterlilies need a bit of extra food, so it's easier if they're in pots. Others are less fussy.

Posy

Some marginals have super-strong roots and may pierce your liner if left to their own devices but the usual problem is that over a few years a shallow pond will fill up with mud, rotted leaves, escaped compost from pots and so on. It's a pain to clear, especially if you have plants rooting into it.

Collareddove

Thanks everyone.  So today I have bought some aquatic pots of varying sizes, I already have hessian suitable for lining the pots. My question is, do I really need the special aquatic compost, or can I use garden loam, or compost or whatever? I asked them at the nursery, (normal one, not  aquatic), and they said they thought not necessary; they thought the advantage is aquatic compost is heavy so assists the pots to sink. Some advice please.

Fairygirl

I don't bother using specific soil. The only problem is that some garden soil is quite nutritious [mine is as it's clay] but I used the manky rubbish that I dug out to make the pond in the first place, combined with gravel. 

Collareddove

Well that's a new one on me Fairygirl!  I always thought clay was poor quality soil which is why it needed added compost/manure/grit etc to make it workable in the garden.
I will do as you suggest, use the soil dug out to make the pond, and add plenty of grit to it.  Slightly clay-y loam.  Will that be ok?

Posy

It depends how much clay there is. If there is some loam mixed in  it's better and if water drains and oxygen can get in it can be quite rich. Solid, dead clay that is just waterlogged or like concrete needs lots of muck added to transform it into a life-giving medium.

Redwing

I use garden soil, which in my case is clay and it works well.  Special aquatic compost is stupidly expensive and not necessary.

Fairygirl

I used the stuff I dug out for the pond plants - manky, yellow clay. It's perfect for that purpose. 
Improved clay can be too nutritious for certain pond plants [fine for water lilies] but if you add some gravel it's absolutely fine, as it just reduces that nutrition. You may not even need to worry about any grit or gravel. My ground for this pond was where there had been paving and red gravel initially, so it was just a mixture of everything under the turf I took out. I've done that several times creating ponds   
 
A good clay soil is ideal for many plants in a border because of that nutrition, but it has to be improved to make it workable, and to aid the drainage in wet weather, and retain moisture if you're in a hotter, drier area where it dries out and crack in summer. We don't have to worry about the latter here, just the former