We regularly get visited by frogs in our garden, I can tell by the different calls they produce. The trouble is that they tend to visit, then continue their wanderings, whereas I would like them to stay, for a while at least. When they come to see us they usually take up residence in the 50mm pipe which is the entrance for waste water into the constructed wetland. This is inconvenient for both parties, because once I know they are there I have to pump the washing machine effluent onto the surface of the wetland, rather than the way I designed it, and it can’t be a huge amount of fun for the frogs either.
The answer to my conundrum is, of course, to build a specific place for the froggies to live, where the water is fresh and they are not cramping my water treating style. Thus the work recorded here. The frogs we tended to get were tree frogs (as I understand it) who had the ability to climb up and into the constructed wetland entrance, so they are my target (to use a poor expression) frog for this project.
The Frog Hotel
The raw materials!
The base container
The first thing I needed to get hold of was a large container to put the hotel together in. After a quick search I found a large unglazed terracotta pot that was 370mm wide at the top by 160mm high. It was designed to be a plant pot so there was a decent sized drainage hole in the bottom, which I needed to block, so I placed a bit of plastic underneath the hole and filled it in with ‘wet area’ silicone sealant.
The water reservoir
The froggies like a damp environment so I wanted to make sure that the bowl in which the tubes would be sitting would always have a reasonable level of water in it, so I decided to use the same approach as I had previously for the bird waterer/bath and the beneficial insect waterer. This involved setting up a tube with an upturned bottle in it, which acted as water reservoir.
The first action was to (using more silicon sealant) affix a 50mm floor flange turned upside down on the bottom of the pot. To allow it to get a bit closer to the edge of the pot I cut a small curve around one side with my band saw first, then applied plenty of silicone to the flange and put it in place. I then left the set up for 24 hours so the silicone in the hole in the bottom of the pot and securing the flange could cure.
This time I did not have a spare glass cordial bottle to hold the water so I had to get a bottle from the local ‘El Cheapo’ shop, which had a similar profile. The upside was that it was a one litre bottle, rather than a 750ml bottle like the other cordial bottles. It was then a case of measuring up how far the bottle neck goes down into the 50mm tube (incorrectly as it turns out), so that the mouth of the bottle is positioned a 20mm or so below the rim of the pot when the tube has been cut to length. I then drilled some holes in the side of the tube for the water to flow out from the bottle into the pot and siliconed (is that a word?) it into the upturned flange, to make it steady.
The only thing left to do was, as I had done with the other designs, was fit a rubber 25mm cuff (used to connect 25mm flexible greywater tubes to 34mm outlets) to the mouth of the bottle. Being a different bottle it did not fit perfectly at first, but I found if I folded the cuff over on itself, wet the bottle neck and then slid the cuff on, it fitted pretty well. The bottle would now fit securely in the tube.
Frog Hotel ‘Rooms’
The rooms are in the form of vertical PVC pipes of various diameters and lengths, some fitted with 90⁰ elbows, some without. Just reading around, pipes of 90mm, 40mm and 25mm are recommended but I suspect the diameters are not critical in themselves, it being more important to have a variety. As previously mentioned we have had frogs take up residence in your 50mm constructed wetland inlet pipe. I looked at what I had floating around and seeing as I had lengths of 90mm, 50mm, 40mm and 25mm I decided to use lengths of all four.
Regarding the length of each hotel ‘room’, this was pretty much up for grabs as different sources recommended either figures that differed between sources or not figure at all. I took this to mean that the lengths of the pipe were not critical. Bearing in mind that the 50mm entry tube into the constructed wetland, which has proved popular, is 350mm long. I collected what tubes I had and constructed the following –
- I length of 90mm diameter tube at 500mm long (with 90⁰ elbow)
- 2 lengths of 50mm tube at 500mm long (1 with 90⁰ elbow, 1 without)
- 1 length of 50mm tube at 300mm long (with 90⁰ elbow)
- 1 length of 50mm tube at 200mm long
- 1 length of 40mm tube at 400mm long
- 1 length of 40mm tube at 300mm long (with 90⁰ elbow)
- 1 length of 25mm tube at 330mm long
So you can see from the above there are a mix of diameters and lengths of pipe with half having a 90⁰ elbow fitted. From what I have read the tubes with 90⁰ elbows fitted on the end seem popular with frogs. Maybe they provide extra protection? I don’t know!
It will be most interesting to see which style of frog hotel ‘room’ they prefer when they turn up!
Filling
With all of the tubes ready, I needed some gravel to fill the pot and give some stability to the tubes when upright. Fortunately my daughter was getting rid of some reasonably sized white gravel. I don’t know how gravel is measured but at a quick took it seems to me to be 25mm – 30mm sized gravel. I was a bit concerned about herbicide residues (particularly Glyphosate) from the previous owners so I did a bioassay test (described here) and it was clear. I gave the gravel a wash in clean water anyway and I was ready to assemble the frog hotel.
Assembly
This was a remarkably simple and quick operation. With the pot ready to go and the water reservoir fittings in place, it was just a case of putting the tube rooms together, facing the 90⁰ elbows in different directions (to give the froggies a choice of aspect) and then setting them up in the pot. The pot was sitting on a bench in the greenhouse, which has a slight lean, so of course they all immediately fell over.
To recover from this embarrassment I borrowed some 25mm wide elastic (blue, if you must know!) from Linda, and then tied all of the tubes together securely upright in the pot. It was then just a case of trickling in the gravel in by hand and making sure it was evenly distributed and with no open spaces. Once the gravel was in and levelled, I removed the elastic and everything stood up fine, we were right to go!
Siting
I wanted to put the hotel in a place where it was likely to come to the attention of any frogs passing through, so I picked a place between the back wall of the house and the constructed wetland. The frogs had already colonised the constructed wetland previously so I figured the hotel would be easier to get to. It was also in a very protected area which is covered by the foliage of the constructed wetland and the mandarine tree, so that it was in full shade or dappled shade during the day.
I dug out a small depression and made sure the bottom was mostly level, then went to grab the hotel from the greenhouse. It was pretty heavy, so I wanted to get it in final position before I filled it with water. After some mucking around and testing with my spirit level I got it to where I wanted it to be, and even built a small ramp of dirt up one side to improve access.
Now I was ready to fill it with water! I filled the pot until it was about 10mm below the top edge of the pot and then placed the filled water bottle into the tube. The water came gushing down into the pot as it was designed to do, but unfortunately it kept going and overflowed the side of the pot. *sigh* I had set the bottle up too high so the water didn’t stop before it hit the rim of the pot. I used a tenon saw to remove 25mm from the end of the tube and while it was a bit clumsy, it certainly did the job. It could probably stand the removal of another 3mm-5mm but I will see how it goes.
It has been in place for a week or so and so far no froggies, although those that know suggest that the frog hotel comes into its own in autumn when the frogs are looking for winter accommodation. A full bottle of water will keep it topped up for a couple of days, although it is mid-summer and pretty hot. I expect it will require less top-ups in the cooler weather. We shall see!
Check out our YouTube video on making a Frog Hotel
