How to Automatically Water the Plants on Your Deck

Deck gardens are pretty, tidy and breezy. They may even be the only kind possible in little townhouse lots obstructed by tall opaque fences with second-story decks that turn the yard into a cellar and the deck into what the yard should have been, but higher maintenance. But plants in little pots need watering individually and often. What a pain. Let's automate it.


  1. 1
    Choose a tap. Generally you'll want an outdoor faucet, in the vicinity of the deck. Attach a wye-adapter to it for the option of normal use alongside the irrigation system; use a metal-bodied one for lasting strength and seal its threads with teflon tape to prevent drips. If your faucet doesn't have a backflow preventer, install one right after it to prevent dirty water flow back into the mains in the event of pressure loss.
  2. 2
    Plan a "drip" irrigation system (not a "soaker hose"). A programmable timer typically goes at the faucet, followed by a simple pressure regulator, light 3/4" semi-flexible UV-resistant black plastic "main line" to maintain relatively uniform pressure throughout, and side lines of solid and then perforated "micro tubing" to slowly deliver water to the plants. There are also "micro sprinklers" to spray water a few feet. But all that's really needed are the main line, a punch and micro couplers to supply solid micro-tubing to the individual pots, lengths of perforated tubing to lay just under the surface of each one's soil in proportion to its water need (generally, its size), and plugs for the end of driplines and mistaken punctures to the mainline. Small garden areas near the deck can be watered similarly. A "starter kit" will have most of the essentials, including instructions.
  3. 3
    Anchor the main line unobtrusively around the area to be watered. 3/4" nail-on tubing clips sold for other kinds of plastic pipe hold it well; keep it low to reduce dripping on wires or even lights strung higher on the deck. A good place may be the underside of the wooden screens under railings (likely present on and accessible from within a second-story deck), or the undersides of the deck girders. Keep curves loose to avoid kinking in the sun; trim the end to length with some to spare after the basic format is laid out.
  4. 4
    Add pots and a solid micro-tubing lead followed by a capped drip line for each. The pots must have drain holes to prevent flooding and root death with excessive rain; they should sit on ventilated grids or saucers with feet, or hang, to prevent deck damage from water pooling underneath. Side "window boxes", or baskets and even small or not-too-full upside-down planters cantilevered off metal arms are a great way to conserve actual deck space.
  5. 5
    Configure watering. Small, sun-warmed planters need watering often as the plants drink vigorously. But constant sogginess suffocates roots and breeds fungus and bugs. And overflow drags off nutrients. Try once a day for five minutes (or just a little less time than produces much runoff); more often if the plants wilt much between waterings. Some planters include large reservoirs with sponges to reabsorb "just enough" over time.
  6. 6
    Fertilize periodically. If the plants look pale or yellow, they're probably weakening from lack of nutrients. A spoonful of cheap granulated general-purpose fertilizer--however much is recommended for periodic application to roughly that many square feet, or several gallons of water--on top of the soil will soon absorb in from watering or rain and fix the problem; apply every few weeks for best results. Pre-dissolving the fertilizer, or expensive gimmicky fertilizer costing more than a few dollars per pound, is unnecessary. (The most "organic" option is manure, but for obvious reasons that should cost little, too.) A "scorched" look to tips of leaves can mean too much fertilizer -- "over-water" awhile to leach it out.


  • Big vegetables and fast-growing flowers need full sun for even minimally acceptable results. For locations shaded even a few hours a day by things like a house, tree, fence, furniture, or even dense deck banisters, naturally medium-sized crops like peppers, cherry tomatoes, herbs, and small flowers can be much more reliable. For locations shaded half or more of the day, stick to plants specifically identified as part-sun or shade tolerant, as the case may be.
  • Rechargeable (but low-self-discharge) or lithium batteries can be best for set-and-forget devices like watering timers because they do not leak when they die.
  • A too-barely-open spigot or other quirks of the irrigation system may be the cause of mysterious "water hammering" noise from pipes in the house. Try adjusting it if this symptom crops up.


  • Beware of mosquitoes breeding in drip pans if you choose to use them for better fertilizer retention. Ideally the surplus water will reabsorb every few days. If it persists, sufficient fertilizer concentration may prevent critter growth. If that doesn't work, try a drop or two of vegetable oil on there to suffocate the bugs, or a spritz of food-safe pesticide onto the water to poison them, or (if the water hasn't been poisoned, persists in quantity indefinitely and is relatively low in chemicals) even some guppies or mosquitofish to breed and eat them.
  • Consider the consequences of automated water flow gone awry. A pipe could break or a valve could stick open; a few wilting plants generally beats thousands of gallons of water waste. Drain the system, including the outdoor spigot's supply, before freezing weather. "Fragile" plastic devices can be best because they'll break before wrenching apart the spigot. Open the house valve just enough for a few-gallons-per-minute healthy flow and good pressure through the drip irrigation system so the unlikely event of the timer sticking open won't waste huge amounts of water. (Multiple timers in series may reduce the possibility of sticking open, at the risk of more often not allowing water to flow when it should.) A coupling sold for washing machines may be able to halt flow in the event of disappearing back pressure that would indicate a break. If you'll be away for long, mention the apparatus to a neighbor who can at least turn it off in the event of a gusher.

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Categories: Indoor and Patio Plants | Gardening