Pond size
Some dragonflies will breed in ponds with a surface area as small as four m2, but many species need a pond of over 50 m2. Frogs and smooth newts may breed in ponds as small as one m2, but toads and great crested newts prefer larger ponds, above 15 m2. Frogs usually spawn in water 7-10 cm deep, in submerged plants; toads and newts spawn in water 10-50 cm deep.

Making your pond
Most pond lining material is made from either polythene or butyl rubber, but some ponds are clay or concrete-lined. You can buy pre-formed plastic liners from garden centres, but, for wildlife, many of these are more trouble than they are worth: they are difficult to fit and level and tend to be very steep-sided. They are also very expensive for their size.

Having dug the basic hole for your pond, line it with a smooth layer of newspapers, sand or old carpet to prevent the plastic liner being punctured. Lay the liner in the hole, but do not stretch it too tight. You must allow room for it to expand. Make sure the liner is large enough to overlap the edges, and weigh it down. These edges can be covered by turf to give a pleasing appearance and to protect them from sunlight. Add a further layer of sand or soil over the liner once you have laid it to prevent its being broken down by sunlight.

Fill your pond with water, and allow it to stand for a couple of days before stocking it to allow any chlorine in the water to dissipate.

Stocking the pond
It is often best to allow your pond to stock itself. You may be surprised just how rapidly insects, frogs and plants colonise it. A bucket of water from an established pond will help to boost the wildlife of your own more quickly.

If you simply cannot wait, stock your pond with native plants (sometimes listed under the scientific names given in italics below), either from other garden ponds or from garden centres Winter' is the best time to do this. ft is best to have a mixture of submerged plants, floating plants and emergent plants, those that are rooted in water but whose foliage extends into the air. Native plants to look out for are:

• Submerged Water-miIfoil Myriophyllum, curled pondweed Potamogeton crispus, hornwort Ceratophyllum, water starwort Callitriche.
  
• Floating White water-lily Nymphaea alba, ivy-leaved duckweed Lemna trisulca.
  
• Emergent Yellow iris Iris pseudacorus, meadowsweet Filipendula ulmaria, purple loosestrife Lythrum salicaria, rushes Juncus, sedges Carex, greater spearwort Ranunculus lingua, water mint Mentha aquatica, water forget-me-not Myosotis scorpidides.