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This page contains a list of Frequently Asked Questions (FAQs) about our Container Irrigation & Drainage. This document contains many answers, yet not all the information you may need or require. Please refer to our CWM Field Manual. If you would like more information about planter drainage, please check the "Planter Drainage FAQ." For product information, please go to the pots and planters section of our website.
Below, there are three sections of questions & answers:
- Set up
- Regular Maintenance/Troubleshooting
Insert-Style, side view
CWM Modular Style, side view
Components of the Insert-Style
Components of the CWM Modular Style
1. Can I plumb an irrigation line to the system for refilling?
No – this is a hand-filled system. It is usually used when plumbing isn’t present to reduce the amount of hand-watering labor.
2. What is the moisture sensor?
Where does it go?
The moisture sensor is a clear tube with a white tip. It must always be buried in the soil (with the clear end attached to the wall) approximately 1/3 of the way down the root ball of the main plant, and inches below where it attaches to the irrigation module (see Figure 1).
If the sensor is not buried, the system will not properly function.
3. Where does the water come from?
The water enters the soil at the bottom of the planter and wicks its way towards the top (see Figure 2 below). It stops when it reaches the moisture sensor (see Figure 3 below). The moist soil closes the sensor and starts the vacuum, which prevents more water from entering the pot.
4. Can the moisture level be adjusted?
Raising the level of the sensor causes the soil to be wetter. Burying it deeper will cause the soil to be drier.
5. What is the difference between inserts and CWM?
Inserts are double-wall non-decorative pots, typically dropped into decorative planters. The plant and soil go on the inside, the water between the walls. The CWM uses the same moisture sensor technology but features a series of water reservoirs buried inside a pot (see Figures below).
6. When should I use an insert vs. a CWM system?
Inserts are recommended for interior applications, pots smaller than 36”, and high-end residential projects. A CWM system is more flexible, allowing for much bigger planters, planting areas, and where having more soil volume is an advantage.
7. Is there an advantage to one over the other?
Inserts are usually faster and easier to install and maintain. However, they can’t go in as many different sizes as the CWM. The CWM is modular and can be tailored to fit any size planter or planting area. For extremely large planters or beds, multiple units may be used.
8. What type of soil is recommended?
Tournesol Siteworks recommends the use of a good grade of a soilless potting mix when using any container irrigation system. We typically recommend a blend of approx. 1/3 peat, 1/3 composted organics, and 1/3 sand, or expanded slate or shale. This blend has good capillary action, but still has enough structure so it doesn’t compact and still drains.
*Never use field soil in any pot or container planting!
9. Can the CWM system be used in an interior application?
Yes, CWM may be used for interior applications. The container that they are in should be waterproofed and not have a drain hole.
10. What does it look like inside the planter with the CWM segment in a square, rectangle, or round shape? (See figures below)
11. When connecting CWM modules, can I use zip ties if I don’t have the clamps for the joining hose?
The key to the success of CWM is that no air gets into the system, which is why it is delivered with hose clamps to tighten around the connections. If you don’t have the clamps, zip or cable ties are an acceptable way to fasten the hose on the barb. Be sure to cinch them tightly. A good way to ensure the seal is to use 2 ties per connection tightened opposite of each.
11A. How long should each joining hose be?
The hose is delivered in a roll so that it can be field trimmed as required for the equal spacing of the modules. Hoses should not kink.
12. How deep is the CWM planted in the container?
Remember, the water wicks up from the bottom towards the sensor. Depending on the soil, its capillarity can only lift water 18-20”. So, if you have a very deep planter, you may not want to place the CWM all the way at the bottom.
13. What goes below the CWM?
It’s best to use more soil under the CWM – it will wick the water from below. Drainage rock can also be used, but the water that drains will be lost to the plant. There are a lot of options with this, so you may want to consult with a Tournesol expert to discuss (see figure to the right).
14. If I use a pump-out system where does the CWM system go? (see figure to the left).
Drainage questions are often more important than irrigation! A few are below, but for more in-depth answers, talk with a Tournesol expert.
15. Why is drainage important?
Too much water in the soil will kill the plant. No matter the source, a drainage hole will allow the excess water to exit the pot.
16. What are my options if I don’t want the pot to drain?
First, make sure that the planter is ordered without a drain hole (FRP pots are standard without, GFRC and metal pots are standard with). Typically, a pump-out tube is used to manually evacuate excess water, either with a siphon or a pump. We sell a good one.
17. What are my options if I want a drain hole?
Again, make sure that planter is ordered with a drain hole (you can drill it in the FRP pot easily). If using a drain hole with an insert, a saucer under the pot will keep the drain water in check. If using a CWM, there is an overflow drainage adapter delivered with each system. Use it.
18. Rainwater is filling up my insert, how do I drain it?
Insert-style irrigation systems have an overflow drain on the side (see Figure 4). When used indoors, insert the enclosed plug into the drain. For the exterior, the system will allow excess water out. If filled with water, the drain may be plugged – remove the insert from the pot and check. Alternatively, make sure water is draining from the pot below.
19. What does the Overflow Drainage Adapter (ODA) do?
The ODA sits on the bottom of the container and raises the drainage hole higher in the soil layer. Without the use of an ODA, some of the water coming out of the CWM will drain out immediately and will be lost instead of being used by the plant. For the most efficient use of the CWM system, the use of ODA is strongly recommended (see figure to the left).
20. How many ODAs do I need for each size planter using a CWM system?
One for each drain hole. If using more than one, they should be at the same height.
21. Can we use Overflow Drainage Adapter (ODA) without CWM?
Yes, we sell the ODA separately. Many projects, especially in climates that don’t get much rain, use the ODA in place of a saucer.
22. Can the height of the ODA be adjusted?
The ODA comes standard with a 6” section of ABS pipe putting the drain depth at 6”. The height can be adjusted by cutting the pipe down to the desired height or increased by using an ABS coupler and additional ABS pipe. A taller overflow adapter will “capture” more water and may work for planters without space for saucers.
23. How does ODA exactly work?
The planter will retain water up to the height of the ODA, roughly 6” of excess water, or the drain depth of the cut-down or extended ODA. Once the water level reaches the ODA, it flows out the planter drain hole below. The filter fabric prevents soil from washing down the pipe. However, the drain water will carry any staining tannins absorbed in the water (see figure to the right).
24. If the drain hole is flat on the ground, how does the water get out?
Usually, water will find a way out. The bottom of the ODA is not flat on the pot, so enough space is created to allow drainage. We can provide 1mm and 2mm neoprene shims as well.
25. How often does the system have to be refilled? How will I know?
Filling the reservoir should become part of the regular cycle of plant maintenance. Start by filling the reservoir, and then monitor the soil moisture carefully during the initial establishment period. Don’t just look at the top of the pot, as the topsoil usually will look dry – check the soil several inches down. If the soil below is dry, the filling frequency may need to be increased. If too wet, or if excess water is leaking from the bottom of the container, fill the reservoir less frequently, or don’t put as much water in the reservoir. Watch the health of the main plant for signs of stress.
After several weeks, the water needs of the plants and the soil moisture levels should gradually stabilize, and a regular schedule can be established. Remember that the plants’ water needs may change with the seasons or weather and that the refilling interval may need to be changed accordingly.
26. Do I have to place the stopper back in the fill tube between refilling?
The stopper is critical to the sensor’s function and must be replaced securely every time the reservoir is filled. All CWM Systems are equipped with a tamper-resistant stopper. The stopper expands and seals by turning the hex head bolt in the middle of the stainless washer clockwise. Turn the bolt counterclockwise to remove the plug (see Figures 5-7 below). The stopper is attached to the fill tube with a short leash so that it isn’t lost.
27. Can I top water underplanting with the CWM system? How do I make sure the small plants and flowers don’t die right after planting?
Top water the under-plantings with a medium amount of water, as required, until their roots have grown down to the moisture zone (at the level of the sensor). This will typically take 1-3 weeks of maintenance. You’ll see the plants thrive once they reach the moist soil below.
28. Can I add nutrients through the fill tube of the system?
Water-soluble fertilizer can be dissolved in water before adding to the reservoir; plan on using ½-1/4 the manufacturer’s recommended strength. Don’t add the fertilizer without premixing, and don’t use non-water soluble or time-release fertilizer.
29. What do I need to do to winterize the reservoir systems?
Because the CWM is insulated by the surrounding soil, relatively little is required for winterization. Allow the system to go empty by the first hard frost. Begin decreasing the refilling frequency as autumn approaches and stop entirely before the first hard frost. Because of the nature of the materials used in constructing the CWM, it isn’t necessary to have the reservoirs completely empty.
30. How do they handle extreme temperatures?
There is little concern for the system in high temperatures. However, if the soil appears dry and the plant suffers, the filling frequency may need to be increased.
31. Is water released as I pull the stopper and fill the system?
Yes – by removing the stopper you break the vacuum holding the water in the reservoir (see Ques. #26, Figure 5). It will continue to be released until the stopper is replaced and the vacuum is re-established.
32. Should water be pouring out of the bottom of the planter?
Water should not be pouring out of the system, especially if you’ve replaced the stopper (see Ques. #26, Figure 7). There is likely a problem sealing air out of the system. Examine the connecting hoses, making sure that they are secured on the barbs. Look at the sensor module, and make sure that the sensor hose is held in place by the rubber grommet. Check that the sensor tube is placed correctly into the soil, and the soil is well-packed around it. Finally, check that the cap is on and tight on the fill tube and that the fill tube is glued properly.
33. Why is the reservoir full the next time I go to fill it?
This issue usually only occurs after the plant has been maintained on the system a long time. If the reservoir level drops a few minutes after removing the sensor hose from its grommet, the moisture sensor should be replaced. If not, it’s probably the plant itself. The roots of the plant will grow towards the water source. At some point, they grow into the holes allowing water in the system and prevent any more water from getting through; this can be resolved by un-planting and removing the roots from the reservoir.
34. How often do parts need to be replaced?
Parts for the CWM system and inserts should last many years – the typical replacement cycle is 3 to 5 years. Watch for cracks or nicks in the stopper and the grommet that supports the sensor hose. Replace, especially if there is air getting into the system and the soil runs wet. If the sensor hose has build-up inside the hose, or the system stops watering, then a replacement is needed. When replacing parts, it is recommended to check the hose clamps and tighten again if needed.
35. How do I clean the system, and when?
Cleaning of the system should not be needed. However, if build-up does occur with the system try flushing the system with water first. If this does not clear any “clogs” occurring in the system, then try mixing a little water and bleach into the system. Be sure to fully rinse and remove any bleach that might still be in the system before replanting.
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