Seeing this indoor question made me look for an outdoor version of the same but found nothing, so here goes:

We've got a balcony with a very large planter on the outside in which we have planted some small flowering plants for decoration. The planter faces south so it gets a LOT of sun during the day, and my wife waters it by hand nearly every day.

We're worried that the plants won't survive four days in direct sunlight without watering, but we haven't found a good solution for automatic watering. I don't want to spend big money on ready-made systems.

We have tried the inverted soda bottle with a pinhole in the cap but the bottle was drained within a few hours. This solution won't work over several days.

What alternatives can I try?

5 Answers 5


If I am not mistaken in Israel in the 60's they pioneered subterranean irrigation with buried terra cotta jars.. Perhaps you could use a clay flower pot with the bottom corked, and the top covered... A few of those buried in your planter may do the trick... The downside would be that you would want to test it first...

I would retry the soda bottle thing... Your hole may have been too big or you may have had a leak.

  • 1
    Ironically, I'm upvoting and accepting this because of your last paragraph. Yes, it turned out that all I needed to do was try again. Same bottles, same holes. Only this time, the soil was already wet and didn't suck the water out immediately. Works as intended!! Commented Jun 11, 2012 at 18:53

Wood chips are effective in keeping the soil moist but inert and will not absorb or release any nutrients into the soil in the short term when applied as a mulch. If mixed into the soil they will tie up nitrogen as they slowly decompose.

Twigs and leaves from the forest will provide some nutrients and act as a mulch but are also likely to contain insect and slug eggs. In a planter, with no predators they could get out of control.

Instead of using wood chips and leaves I recommend a commercially prepared mulch which you can work into the soil next season and will keep the soil moist this season.

If you combine it with an automatic watering season as seen here you have a solution for this year.

An even better solution is to set up your planter as a self watering system as described here. This requires reworking your planter to have a water reservoir with fill tube in the bottom. An air space separates the reservoir from the soil area and a capillary wick draws water from the reservoir to the plants. Simple and effective when set up.

  • I very much like your final paragraph! That's an idea we will certainly do, although it will have to wait until next season. Wood chips seem to be the best "quick fix". Commented Jun 8, 2012 at 12:37

The point is the soil. The soil gets moist when you give it water and the water flows down, down, down.

Depending on the type of soil you have on the bottom of the planter, the water stays in a while or not.

When you use mulch on the spots most covered with sunrays, you can stop or slow down the evaporation of the moist. What kind of mulch you could use? I suggest to have some woodchips on top.

These woodchips should be organic, natural, untreated wood, leaves, twigs etc. Maybe take some from ground in the forest, depending how much you need and if it is allowed.

When you use green, fresh chopped woodchips it will release to much nitrogen and your plants will probably die.

When there already is too much sun, I would soak the woodchips for a couple of hours in (collected rain) water. This way the sun will first dry out the woodchips. The woodchips will slowly absorb water from the soil underneath, but it still covers most of the soil in shade. This way it stays moist.

This way you slow down the process of extracting moist from the soil enormously. You can choose to keep the woodchips on top, because it's good for the soil too.

Watch this film for more information about woodchips: http://www.backtoedenfilm.com


Similar to, but not an exact duplicate of this question. My answer will be the same for both.

I travel frequently and use the "Hydrospike". Basically it siphons water up from a container into a clay spike, which slowly diffuses the water. The flow can be "regulated" by the number of spikes you use ;-) The physics doesn't quite make sense to me, but against all odds, it seems to work quite well. The longest trip I've used it for was 10 days, with outdoor plants in warm weather, and my plants were all healthy when I came back.

The downsides I've faced are

  • size (this is too big for really tiny pots)
  • arranging the water reservoir. The water tube needs to drape down into the reservoir, which must be below the spike. Unfortunately, the water tube is only so long, so you may need to do some furniture arrangement to get the water up high enough, but not too high. I've seen other products on Amazon that come with some reservoirs designed to attach to the side of pots, and I tried one once, but it didn't fit my arrangement.
  • constant moistness (I don't leave this going for too long, but I imagine if you did, you might start to have fungus or soil bug problems.

The arrangement I use is an Ikea side table holding some paint buckets full of water, with many Hydrospike tubes feeding two yard-long elevated planters. I made some clear plexiglass lids with small gaps for the tubes, to limit evaporation and bug invasion, but allows me to check the water level.


On my two balconies, I use both Big Drippa (drip irrigation with a sack of water, tubes and drippers) and another setup with a water pump. I made a video showing the Big Drippa setup: https://youtu.be/_FgVsac5eMU

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