First, scout out the location for your pond. Maybe you would like to see the pond from your living room or home office window. Perhaps you want it close to a patio or you want to see it from your deck.
You want to stay away from an area close to (large) trees. Trees have this habit of shedding leaves each fall and you would have to scoop them out after they have fallen in your pond. If you would like to grow some aquatic plants such as water lilies in your pond you are looking for a spot without (much) shade. Most aquatic plants like to have at least 6 hours of sun. Last but not least, tree roots may be in the way of your pond and you would neither want to disturb these roots, and possibly kill the tree, nor have the roots invade the liner of your pond.
If you plan on installing filtration for the pond or you want to include a waterfall, you will need to have access to outdoor electrical outlets. In that case, check the building codes for your state (or town), get the required license and have a licensed electrician install the outlet for you.
Once you have the perfect spot for your pond, consider the shape of the pond. Do you want a free form pond or something round, square or rectangular? Are you considering buying a preformed pond shell which you pop into a hole or do you want to create a pond using liner material?
A preformed pond shell is an excellent option if you are considering a smaller size pond. These shells are strong and they generally have different shelves which allow you to add a variety of water plants. There are only a certain number of varieties of preformed shells available, so you are limited in your choice. Also they are generally speaking not large ponds. However, if you have only limited space, using a preformed shell might make sense. Using a pond liner, though, gives you more versatility in creating your pond.
How do you determine what shape you want your pond to be? If you are thinking about using a liner, take a garden hose or long piece of rope and lay it on the ground in the area you want to build your pond. Do you like the way it looks? Is it too big for the area, too small? If your pond will be a free-form pond, try to stay away from too many curves which will complicate your project.
How deep do you want the pond to be? 18 inches is considered a perfect pond depth, although you may want to go deeper if you live in a cold area which routinely ices over in winter. Check to see if your municipality has any restrictions/building codes for ponds. For a small pond you are probably ok, but if you are considering a large pond, it is better to have your paperwork in order before building it and finding out afterwards that you have violated building restrictions.
If you are considering having a few goldfish in your pond, you don’t need to dig deeper than 18 to 24 inches. If, on the other hand, you are thinking about keeping koi, those beautiful ornamental carp, you really can’t do without very good filtration, lots of water movement (waterfall) a deeper pond, and if possible, a bottom drain. I would not recommend anything less than 100 gallons for just ONE small koi and even in my 1200 gallon pond I have only a few koi fish. Of course, once they spawn there might be more, but a lower fish load (less fish) in a big pond will make for some very happy koi.
Now that you have decided on a shape, it’s time to start digging. But wait; before you dig, figure out where to put all the excess soil from this excavation. If you have low lying areas in your garden, you may want to distribute the excess soil there. If you are considering a waterfall, use the excavated soil for building the berm that will become the base for your waterfall.
If you decided to go with a pre-formed shell, put the shell in the desired spot right side up and place short stakes at one foot intervals around the shell. Remove the shell and start digging. Make sure you dig to the desired depth. Once you have excavated all of the soil, put the shell in the hole and see how well it fits. Is one side slightly higher than the other? Take the shell out again and dig a little more on the one side. Nothing is worse than having a pond in place, specially a pre-formed pond, which is lopsided. Once you have the pond perfectly level in the ground, you can fill it with water. Then, let it sit for a day or two, especially if you plan on adding some fish.
Most, if not all, pre-formed ponds have shelves on one or several sides of the pond. These shelves are for potted aquatic plants such as water lilies. To disguise the plastic lip of the pond sticking out of the soil, use stones as an edging. Additionally, you can plant a variety of different plants around the pond. As a background you can use a shrub for height. Around the sides you can use some lower growing perennials and in front you can use some fast growing annuals. These plants will grow over the stones and incorporate the pond into the landscape. Aquatic plants will provide cover and shade for any fish you plan on adding.
If you want to use a pond liner, you first will have to determine how much you need. You calculate the size as follows:
Liner length: pond length + (2x depth) + 2 feet overlap.
Liner width: pond width + (2x dept) + 2 feet overlap.
So how much liner would you need for a 10 feet by 8 feet pond which is 2 foot deep?
Length 10 feet + 4 feet (2x depth) + 2 feet (overlap) + 16 feet
Width 8 feet + 4 feet (2x depth) + 2 feet (overlap) = 14 feet.
Answer: You would need a piece of pond liner 16 feet long and 14 feet wide.
If you use a pond liner, first of all make sure you get a good quality liner, which will last you for many, many years. There are now liners on the market which come with a 25 year warranty and a bit of research beforehand will save you the trouble of dealing with a leaky pond liner afterwards.
After you have dug the hole make sure you remove all sharp rocks and protruding roots. Now spread 1 to 2 inches of sand in the hole for padding. Or, if you happen to have access to some old carpet or carpet padding, use that as an alternative. Cheapest of all; use newspapers as padding. While you are lining the pond with padding, make sure the liner is unfolded before installation. Large pieces of pond liner can be difficult to work with when they are stiff. But if you leave it unfolded and in a sunny/warm spot for a short amount of time it will become much more pliable to work with.
With the pond padding in place, now pick up the liner and walk it over to the pond. (It's nice to have an extra pair of hands to help out at this point.) Drop the liner in the pond and make sure it extends evenly around the pond (remember that 2 foot overlap?!). Minimize the number of small folds by pulling and tucking them into large folds. Slowly fill the pond with water and continue to adjust the liner as the water rises.
So now you have a plastic lined water filled hole in the ground that sticks out like a sore thumb. Build a rock border around the edges, allowing rocks to overhang the pond, disguising the liner. Backfilling soil behind the rock edging creates a barrier that holds the liner upright and prevents drainage and run-off from the pond. At this point you can trim any excess liner still surrounding the pond.
Now start aqua-scaping your pond. Add plants, both submerged plants, as well as floating plants. Add rocks in the pond. Incorporate your pond into your landscape by adding plants around it, just as you would do for a pre-formed pond. The picture below is pond number 5, installed in the spring of 2010 in the memorial garden dedicted to my mother.
Last, but not least, add a small fish or two to your pond. If you keep the fish load low and have plenty of plants in your pond, it will become a perfectly balanced ecological system. Any mosquito larvae in the pond will be eaten by the fish. The fish will also feed off algae and other microscopic life clinging to the side of the pond and you will only need to provide a little bit of supplemental feeding. You can make a water change by sticking your garden hose in the pond once ever so often and let the water run out of the pond for 10 minutes or so.
If you like the sound of running water, add a pump to your pond. They are easy to install, but keep in mind that electricity and water do not mix. ALWAYS make sure you plug any electrical equipment into a GFI-outlet installed by a licensed electrician.
Some words of warning about water gardening: it’s addicting and most ponds installed are ripped out and re-installed bigger and better. My first pond was a small pre-formed pond. A few years later it was followed by a larger pre-formed pond. That second pre-formed pond was made bigger by sinking it deeper into the soil, adding a liner over it and building a wall around it. Version four (and hopefully the last version for that spot) is again partially sunk into the soil and surrounded by a seating wall. At about 1200 gallons it suits my purpose and keeps the koi happy. Several baby koi, only weeks old, are currently exploring its nooks and crannies. A powerful waterfall and filter take care of filtration and oxygenation of the water. Water lily pads shade the fish and flowers bloom with abandon. Frogs find a home in it. Dragonflies hover nearby. Perfection, at last, or at least for now....