Drip irrigation for containers

October 19, 2017

Drip irrigation set up
Photo: Helen McKerral

Automating the irrigation of pot plants on your verandah or in your courtyard is cheap, easy and convenient. It saves you time and, if complementing a garden irrigation system, lets you go on holiday anytime.

Electronic timers range from $40 to $170, varying with the number of stations, weatherproofness, and sophistication of programmability; there are even misting timers for tropicals and ferns. You can complete a system for a modest courtyard with fifteen pots for under $120 in just a few hours.

 

What you need: 

1. Pliers

2. Secateurs

19mm fittings: 3. barbed elbows, 4. tees, 5. ratchet clamps. It’s a good idea to buy a few extra fittings and clamps.

6. 19mm polypipe (at required length*)

7. Flush valve (manual/auto) for end of line

8. 4mm flexible poly

9. 4mm punch

10. 4mm tees

11. 3600 adjustable shrubblers (drippers)**,

12. Horizontal two-way brass/galvanised tap adaptor (use the same metal as the tap).

13. Programmable tap timer and connections

* measure the distance you need to cover, and then add 2-3 extra metres just in case.

** or a combination of microsprays and shrubblers for plants that prefer high humidity. Large pots may require two to three overlapping shrubblers.

 

How to assemble

Fit adaptor to tap. 

Fit timer to one outlet, leaving the other free for other uses.

Lay 19mm hose behind pots/along walls.

Starting at tap timer, cut poly to length and join with click-connectors/elbows/tees.  Connect flush valve to end of line. Cinch ratchet clamps.

 

Using attached barb, connect shrubbler to one end of 4mm poly (for larger pots, use 2 shrubblers and a 4mm tee).

 

Position in pot, then run 4mm to 19mm, allowing 100-150mm play.

 

Cut 4mm, punch hole in the 19mm pipe and connect the two using the detachable barb from the shrubbler. Locate the hole behind the pot, preferably shaded from direct sun: heat may sufficiently soften 4mm line to separate under pressure. Buried line is ideal. . If joins are exposed to sun, water early in the morning before plastic softens.

 

Initial Start Up:

To establish correct water flow start with well-watered pots in which mix is uniformly moist. If they’re difficult to wet with a hose or watering can, shrubblers won’t either. Such hydrophobic mixes benefit from a good soak and an application of certified organic wetting agent.

Next, fully close adaptor and open shrubblers three quarters. Open manual flush valve.

Fully open tap. Open adaptor half (for a few pots) to two thirds or fully (more pots).

If using a manual flush valve, close it.

Next, adjust spray diameters and shrubbler placement.

Depending on water pressure, line length, relative elevation and number of shrubblers in your system, fine tune with the adaptor and individual shrubblers so each pot receives right amount of water in the same time period (reduce flow in small pots, increase in larger ones).  Shrubblers should spray the surface of the mix, not hit sides of the pot. Adjust the timer: aim to have a small quantity of water running from the bottom of every pot when the timer switches off.

Set the timer to water daily, twice daily, every few days or weekly depending on plants, pot size and season. Initially, check pots often to calibrate frequency. Small pots need more frequent watering with a shorter duration.

 

Related topics

Organic Gardening, All Gardens, irrigation, how-to, How to…