When DGer HoosierGreen posted about installing a bubble rock, I knew this was the perfect use for my little bargain pond-form. With a young daughter, I didn't want a lily pond that she could fall into, so topping a water reservoir with gravel and rocks sounded ideal. I thought I could probably also come up with a way to include some pond plants or "marginals," like horsetail and water celery.
As with many garden projects, you'll have to start by digging a hole. Decide where you want your water feature, and pick a fairly sunny spot if you're planning to add plants. Place the pond-form in the hole, and use loose soil and gravel to fill in around the edges, checking for level as you go. Use a standard level on top of a straight board placed across the center of your pond-form, or add a little water to your pond-form and eyeball it. Instead of a pond-form or other large no-hole container, you could dig a hole and install a piece of flexible plastic pond liner.
You'll need a pump to circulate water, and something to put the pump in for accessibility. The pump doesn't need to be very powerful, since it isn't providing oxygen or filtration for a fish pond. However, you'll want one with a "head height" of at least 3 or 4 feet, so it can move water from the bottom of the pond-form reservoir to the top of your bubbler or waterfall. Look for pumps sold for use with statuary or water fountains. If your location is far from any electrical outlet, you may be able to use a solar-powered pump. I've started out with a heavy-duty extension cord, but I intend to have an outdoor-rated electrical line run underground to my bubbler.*(see note)
A 5 gallon bucket works great to house the pump. I used a plastic kitty-litter container, because I liked its hinged lid. Drill a series of quarter inch holes around the container, starting about four inches up from the bottom. Water will flow into the bucket through these holes, and raising the inlet holes up a few inches will help keep debris out. Inside the bucket, raise the pump itself by placing it on a brick, again to help keep debris away from the pump. Drill holes in the lid of the bucket for the electrical cord and for the water outlet pipe or tubing.
Place the bucket and pump down into your pond-form. This is also the time to place large plastic nursery pots down into the water reservoir, to create planting holes. Adding wicks to keep the soil moist in the pots will help your plants to be OK even if the water level gets pretty low. Put a knot in the middle of a strip of microfiber towel and thread it through a drainage hole, extending down into the water reservoir and up into the pot.
While you want a top layer of gravel and rocks in your bubbler bog, it's not necessary to fill the entire pond-form with gravel. In fact, you'll have a larger water reservoir if you fill most of the space with pieces of drainage pipe, overturned empty pots, etc. Used sheet pots and plastic six-pack containers crumple up nicely to fill in smaller spaces - recycle whatever you have on hand!
I had an extra piece of landscape fabric, so I put it down before adding the gravel, to further separate the gravel layer from the water reservoir. Fifteen gallons of "¾ inch Deleware" from Irwin Stone gave me a nice six inch layer of gravel for my bubbler bog. Fill your bubbler bog with water, plug in your pump, and make sure the circulation is working well before putting the finishing touches on your water feature. If your bubbler bog will "sit" sometimes without the pump running, adding a big pinch of mosquito control granules might be useful.
Now the fun part, deciding what sort of water feature to create and which plants to add. You could simply attach a fountain kit to the output of your pump, letting the water fall onto the gravel and rocks of your bog. DGer HoosierGreen decided he liked the look and sound of a bubbler rock, with water coming up through a central hole to flow down over a large stone. You can drill some stones yourself with a masonry bit (start small and then widen the hole), or you can have an interesting large stone drilled by the local stone yard.
I may add a bubbler rock later, but for now I'm having fun stacking rocks in various ways to create little waterfalls, bringing the water up through the center of the stacked stones with a length of clear tubing. I'll arrange rocks around the edges of the pond-form and the planting holes, to hide the plastic rims. The small "statuary" pump I'm using doesn't really give me more than a trickle to work with, so my tiny waterfalls are pretty quiet. I've ordered a more powerful pump so I'll have more of a splashing, dancing brook sort of sound.
There's a wide selection of "marginal" plants that grow well at the edges (or "margins") of ponds and in soggy spots, so you can have fun planting your bubbler bog. Use the planting holes in your bubbler bog, either filling them in directly with garden soil (a heavy clay mix is great) or plunging pots down into them. You can also tuck plants (roots, soil, and all) directly into the gravel of your bubbler, especially if you keep the water level fairly high.
Hardy reeds like cattails, horsetails, and pickerelweed are great choices, and I'll bet my lotus would love my new bog. If you're in a warmer zone or don't mind "lifting" and overwintering plants, try some exotic selections like papyrus or elephant ears (Alocasia and Colocasia). Don't forget about the Louisiana and Japanese/Siberian irises that love "wet feet." This is also a great place to grow sweet flag, a pretty plant that can be thuggish if not contained. You'll find lots of choices for filler plants also, such as water celery and moneywort.
Look around your garden. Where can you imagine enjoying the sight and sound of a bubbler bog? Make it happen! You'll be delighted with the result.
** Electrical changes aren't necessarily DIY projects. I plan to have a certified electrician put in my new electrical line.
A big "Thank You!" to DGer HoosierGreen (John Chapin) for posting his "bubble rock" thread. His clear desciprions and photos made me think, "Hey, I can do this!" Hopefully you'll decide to try it, too. If you do, be sure to post photos in the Water Gardens Forum!
For descriptions and additional information, be sure to "hover" your mouse over links and images (let the cursor sit for a moment, and a popup caption will appear. The final two photos in this article are by HoosierGreen, all other photos are by Jill M. Nicolaus.