Hibiscus Plant Care
How to Build a Drip Watering System
For a lush hibiscus garden on a low-water budget,
nothing works better than a drip system.
Why Use a Drip System?
The why is easy. Hibiscus need a plentiful supply of water in the root zone. Plants "drink" their nutrients, and minerals dissolved in the water they absorb (including fertilizer) are what plants use to grow and bloom. If hibiscus do not get enough water during the heat of summer, they will slow down or stop both growing and blooming. They may also drop leaves so that they do not need as much water. In such a case, the plant will look OK, with some green leaves remaining, but it is likely to sit there doing nothing while we wonder what is wrong. We give it fertilizer, but still nothing. So we scratch our heads and perhaps give up. The only problem is likely to be a lack of sufficient water where and when the hibiscus needs it. Once it receives ample water, some time will be needed before growth and flowering resume, but eventually the hibiscus will come back to life and start making glorious flowers again.
Hibiscus roots are concentrated in the first 2 feet (60cm) of soil under the ground and directly below the plant canopy. Although some roots will grow further down or out to the side to find water, all you have to do to water hibiscus well is soak it into the first 2 feet (60cm) of soil below the plant. A very old or large bush may benefit from deeper soaking, but for most hibiscus soaking down 2 feet (60cm) will be enough. Soil dries from the top down, so by watering hibiscus a little deeper than the roots go, you encourage them to grow downward. Ideally they will find a water source below the ground, but until this happens they are totally dependent on rain and what you provide. Different types of soils have to watered according to their needs. Sandy soil will allow water penetration easily, but will also dry out very quickly. Other soils, such as what we have in our yard, are rocky and resist penetration by water. Heavy clay soils are the hardest to deal with, and usually require some work before planting. Improving the soil in the garden by adding appropriate organic matter is always a good idea, but that is another topic for another day.
OK, you say, I realize my hibiscus plants need more water. I have a hose and will just soak them more. Actually, that is better in most cases than not watering enough, but it is not ideal. Why? Two main reasons - first it takes a lot of our precious time to soak each plant every day. In the end it usually turns out not to be every day, and sometimes several days go by without our being able to get to it. Second, in an effort to provide enough water as quickly as possible, most of us will use the full volume of water flow available. In pots this can result in flooding the potting mix, filling air pockets and driving out the vital oxygen that plant roots need. In the ground this style of watering often results in much of the water flowing off to the side before it has a chance to sink down into the root ball. Uneven watering - either too much or too little - is the normal result when watering with a hose.
Sprinklers are not the answer either unfortunately. Sprinkler systems are made to water the entire surface area of a yard or garden area, but the water volume is only enough to water the top 2-3 inches (5-8cm) of the soil. This is what a lawn needs, so sprinklers work well for lawns, and in fact, lawns are what most sprinkler systems were designed for. But in order to get water down to the bottom of your hibiscus' root balls, you would have to run your sprinklers for several hours. For most people, before the water ever reaches the necessary soil depth, it will run off the yard onto streets, sidewalks, and driveways, never reaching the bottom roots of your hibiscus plants.
Remember, the goal is to water your hibiscus so that the water penetrates down 2-3 feet (60-90cm) and spreads outward 1-2 feet (30-60cm) from the main stem of the hibiscus. You can picture a column of water 2-3 feet (60-90cm) wide and 2-3 feet (60-90cm) deep centered under the hibiscus. A drip system will do this for you naturally. As the water drips from an emitter or similar device, it soaks in and spreads out naturally, without driving the air from the soil or potting mix. Drip systems are normally turned on and off by timers, freeing you to enjoy your garden in other ways than just watering it. Drip watering systems are suitable for potted hibiscus, too. The goal with pots is to soak the entire root ball with about 10 percent of the water draining out of the holes so that salts do not build up inside the pot.
How Much will a Drip System Cost?
The Basic Layout
1/2" (13mm) Black Poly Pipe Laid within 1-6' (30cm-2m) of Each Plant
1/4" (6mm) Brown Poly Pipe Connects Each emitter to the Black Poly Pipe
Wells around plants hold water from dripper right above roots
To "do it yourself" you will need some parts, but all of them are available at Home Depot or Lowe's at reasonable cost. The main thing to remember is that each company that makes these parts does it a little differently, apparently in an attempt to force you to use their parts exclusively. Unfortunately, their strategy works. When you buy 1/2" (13mm) black poly pipe it will vary slightly in diameter according to who makes it. That means you can't attach one brand to the other, even though both say they are half inch poly pipe. Grrr! Same with the fittings, which are the parts you use to connect extensions or side pipes to each other. My advice is to do all your drip system shopping at either Lowe's or Home Depot and remember which one you used, so you can add to the system in the future without coming up against mismatched sizes.
Of course, you can let your fingers do the walking and call a landscape maintenance company to give you a quote on setting up a system. This is obviously the easiest method, and should provide excellent results. But it is much more expensive and perhaps less satisfying than building your own system. If you want to do it yourself, you will save money and really understand your system when it is up and working. It's not hard to do, even for those with only a small amount of "do it yourself" experience.
Isn't it Hard to Set up a Drip System? It Must be Too Hard for Someone Like Me!
That's the surprising thing about drip systems! They are EASY to set up! Once you decide which hardware store to use, you'll find all the pieces you need all together in one part of the store, so even a beginner can manage to get the right parts. You can stand right there in the store and push the parts together to make sure you got ones that fit each other and come out the way you thought they would. If you've tried working on plumbing, can't even manage to break open a pipe joint with a pipe wrench, and have decided that plumbing just isnt' for you, that doesn't matter with drip systems! The parts just slide together without glue or tools. You don't have to be strong or smart or know anything about plumbing. If you're terrible at measuring and planning and drawing little blueprints (as Cindy is!), you can just buy plenty of everything and start laying the 1/2" (13mm) poly pipe out on the ground where you think you want it, then just move it around until you find a plan that works. This is the "artisitic" approach to building a drip system. It may not be the most efficient way to figure your plan out, but it works just fine. Don't let your two left thumbs and lack of mechanical, construction, or plumbing ability scare you away from this project. It's EASY! If Cindy can do this, anyone can!
Here We Go... How to Set up a Basic Drip System for up to 150 Plants
OK, enough of the theory. Let's get down to the nuts and bolts of how to set up a drip system. Here are the steps to use in building your own drip system:
Determine where you can connect to your current water supply: This can be either a hose bib (outside faucet where you connect a hose) or a place where you can cut into an existing water line. If you have no experience working with PVC pipe and water supply lines, you should just use the regular hose bib or faucet connection. You just buy a threaded connector that screws into the faucet, then push the poly pipe onto the connector. No glue or tools are needed! This hose bib connector is the first item on your list of parts.
A Hose Bib (Faucet)
The Easiest Way to Connect Your System
Sketch a plan for the main line of water: Once you know your starting point, draw on paper (or mentally if that works best for you) a plan for laying out the flexible black 1/2" (13mm) pipe called "poly pipe" that will be the main water supply for your garden. The pipe should travel from the point of connection at the hose bib around the garden so that the pipe lies within 1 to 6 feet (30cm-2m) of each hibiscus. The layout can be circular or planned as a grid, with side pipes going off at right angles to the main pipe. The poly pipe is not very flexible but is flexible enough to make a circle over a fairly wide area. If you need it to make a hard turn at some point that is not a problem using a T or L connector which we will discuss later. The idea now is to determine how much poly pipe you will need to buy. It is usually found in 50, 100, and 500 foot (15, 30, and 45m) lengths and does not cost much so we recommend you get the amount calculated from your drawing and then add a bit extra so you don't run out and have to make another trip to the store.
The Basic Layout
Lay 1/2" (13mm) poly pipe between plants.
Run 1/4" (6mm) poly pipe to each plant.
Attach drip emitters to 1/4" (6mm) poly pipe.
Dig small Wells around each plant to hold water.
Use either drip emitters or sprinkler emitters for ground cover plants.
The layout of the water pipe in the garden can be anything you want. There are parts that slide into the pipe so that the pipe can be connected at various angles, go up steps, curve over arches, turn 90 degrees, and so forth. The most common of such parts are shaped like X, L, T, or Y and are hollow pieces of plastic that are inserted into the 1/2" (13mm) pipe. They are made to fit tight enough that water will not leak out, nor will the pipe pull easily from the connector, without glue or any other connection pieces. Our system consists of 250 feet (75m) of 1/2" (13mm) poly pipe with enough 1/4" (6mm) pipe and emitters connected to it to water 150 hibiscus and other plants. The main pipe is laid out in a big circle with a side pipe that extends over a jasmine-covered archway and sidewalk into another flower bed on a different side of the house. Our normal water pressure has been sufficient to water all 150 plants at one time with this system, using settings from 1-8 gallons (4-30L) per hour on the emitters, depending on the size of the plant. So feel free to design the system according to your needs, as almost any setup can be accommodated by this type of system.
We did not discuss visibility of the watering pipes yet. Some people prefer that they are buried as much as possible. This is a lot more work and is not necessary if there is some type of ground cover that will hide them. Others do not mind them and after they are installed never even notice them. If you do decide to bury the 1/2" (13mm) pipe, then just dig a shallow trench -- 4" (10cm) deep and 4" (10cm) wide is plenty -- wherever you want the pipe to be. Do not cover over the pipe until the 1/4" (6mm) pipe is connected and the system has been tested. Covering it makes the addition of new emitters more difficult, but the benefit of not being able to see the pipe is worth it to some.
A T-Connector at left
An End folded back and held with an End Closer at right
Use either drip emitters or tiny sprinkler emitters for ground cover plants.
Calculate how much 1/2" (13mm) poly pipe and how many connectors you need: Roughly measure off your garden and use your sketch to calculate the length of 1/2" (13mm) poly pipe you need. Make a list of the various connectors you need to create your planned line: L connectors for corners, T connectors for joining one piece of pipe into the middle of another, end closers for each end you create, stakes to anchor the pipe to the ground. It's smart to buy more than you think you need! No matter how carefully you calculate, something unforseen always comes up, or you somehow manage to break a part while you're working. So calculate what you think you need, and add a bit more of everything to make sure you have what you need.
Count your plants: Each hibiscus (or other plant) is watered by one emitter on a drip system. An emitter is merely a plastic part that allows drips of water to come out when the water pressure is within a certain range. There are many variations on this idea available but what you need to know now is that you need to buy 1 emitter for every plant that is to be watered. Count the plants you intend to water and note the number.
Roll of Black 1/2" (13mm) Poly Pipe (top)
T Connector, Stake to Anchor Pipe to Ground, End Closer (left to right)
Use these parts to lay poly pipe around garden, between plants.
Decide what type of emitter you want: The end point of the 1/4" (6mm) pipe can apply water in many ways. Drippers are one type of emitter. Others are called bubblers when more than a drip of water is allowed to pass through. Some are mini-sprinklers that can spread the water over a larger area, and others are sprayers that spray a small amount of water over a 45-, 90-, or 180-degree area. You can even attach a small diameter soaker hose to water an area of ground cover. There are many possibilities for using a drip system, but for watering hibiscus you need to attach as an end point an emitting device that allows 2-8 gallons (8-30L) per hour of water to soak into the ground around the main stem of the hibiscus.
For our drip system, we chose an adjustable 0-10 gallons-per-hour (0-38 liters-per-hour) dripper that comes ready-made on a stake, with a built-in connector to join it to the 1/4" (6mm) poly pipe, and with an included connector to join the 1/4" (6mm) pipe to the 1/2" (13mm) pipe. It's called an "Adjustable Dripper on Spike" and it's made by Dig Manufacturing. (See picture at right.) This emitter is easy to use for beginners because you only need one emitter per plant since you can adjust the water flow, and don't have to buy any extra connectors. They cost $1 each, so they're more expensive than other emitters, but they work well and they're easy to connect to the system. Plus you save the cost of the 2 connectors that are included.
Spiked Dripper for Each Plant (left)
Roll of Brown 1/4" Poly Pipe (right)
In order to make these emitters gather the water right over the roots of the hibiscus, we dug small wells around the base of each plant. The wells hold the water and allow it to soak down into the roots gradually.
Calculate how much 1/4" (6mm) poly pipe you need: The emitters are connected to the 1/2" (13mm) black poly pipe by a smaller flexible pipe that is normally referred to as 1/4" (6mm) poly pipe. This is even cheaper than the 1/2" (13mm) pipe and available in rolls of 100' (30m). Remember when we planned to place the 1/2" (13mm) pipe within 1-6 feet (30cm-2m) of each plant? That is because we will use the 1/4" (6mm) pipe in lengths of 1-6' (30cm-2m) to connect each emitter to the 1/2" (13mm) (main) water pipe. So, if you are going to water 50 hibiscus or other plants, and the average distance from the 1/2" (13mm) poly pipe is going to be 3 feet (1m), then you will need 50 x 3 feet or 150 feet (50x1m or 50m) of 1/4" (6mm) poly pipe. In reality you allow some slack in this pipe so would purchase 200 feet (65m) instead of the 150 feet (50m) calculated.
Buy the parts: Now you're ready to buy the parts. You've been making a list as you've gone through each step, so you should be ready to go to the store. Make a quick check of your list before you go to make sure it has all these parts:
Small Tool to Punch Holes in 1/2" (13mm) Pipe
- connector to join the hose bib (faucet) to the 1/2" (13mm) poly pipe
- 1/2" (13mm) poly pipe and a rough estimate of how much you need
- T connectors, L connectors, and straight coupler connectors for the 1/2" (13mm) poly pipe
- end closers for the 1/2" (13mm) poly pipe (they look like a double ring)
- stakes to anchor the 1/2" (13mm) poly pipe to the ground
- 1/4" (6mm) poly pipe and a rough estimate of how much you need (3' or so per plant) (1m or so per plant)
- emitters (1-3 per plant, depending on what type you choose)
- connectors that join the 1/4" (6mm) pipe to the 1/2" (13mm) pipe (if your emitters don't include them)
- connectors that join the emitters to the 1/4" (6mm) pipe (if your emitters don't include them)
- a tool that punches the correct size hole in the 1/2" (13mm) pipe so that the 1/4" (6mm) pipe fits without leaking
The tools you need are:
Ground Stake Pinning 1/2" (13mm) Pipe to the Ground (above)
T Connector Joining 2 Pieces of Pipe (below)
- sharp pruning shears to cut the 1/2" (13mm) and 1/4" (6mm) poly pipe.
- hammer to drive small stakes into the ground
Getting all the parts needed is probably the hardest part of building your own watering system. Inevitably more than one trip to the store will be needed. In theory you will get everything you need the first time, but in reality it often does not work that well. We know one fellow who prefers to buy more than he needs and then he returns the left over parts for credit. We prefer to keep left over parts for future projects, but any way you do it the cost is not high.
Put the Main Water Line Together:
- Start by connecting the 1/2" (13mm) poly pipe to the hose bib using the connector you bought.
- Then lay out the 1/2" (13mm) pipe all around your garden, between your plants, as you planned. Use pruning shears to cut each long piece to the length you want. Lay out all side pieces and extra loops you need to cover all places in your garden. Make sure your 1/2" (13mm) pipe runs within 6' (2m) or less of all your plants.
- Join the 1/2" (13mm) poly pipe pieces together with plastic connectors - couplers, T's, L's, etc. Just push these connectors into the pipe.
- Anchor the 1/2" (13mm) pipe to the ground with a few stakes at strategic points, such as at ends, corners, or in the middle of long stretches. Just hammer the stake into the ground and the hook at the top will catch and hold the pipe.
Flush and Close the System:
Once the 1/2" (13mm) pipe is in place and connected everywhere, run the water through it to test that all connections hold and to clean any plastic debris or dirt out of the pipes so that this debris does not clog the emitters later on. When it is all flushed out and watertight, close all open ends of the 1/2" (13mm) pipe with plastic end closers. An end closer is just a set of two plastic rings. Thread the end of the 1/2" (13mm) pipe through one ring, fold the end (it's the fold that closes the pipe), and thread it back through the second ring to hold the fold in place.
End Connector Closing End (double rings below)
Stake Pinning 1/2" (13mm) Pipe End to Ground (above)
Attach Emitters: Now you're ready to attach your emitters. For each plant in your garden:
- Pick a spot on the 1/2" (13mm) poly pipe that is closest to the plant, and use the special tool to punch a hole in the 1/2" (13mm) pipe.
- Cut a piece of 1/4" (6mm) pipe long enough to reach to the plant, allowing a little extra slack.
- Find the connector that came with your emitter (in our case, it was attached to the emitter, and we just had to snap it off), and push it into the hole you just made in the 1/2" (13mm) pipe.
- Push the piece of 1/4" (6mm) pipe you just cut onto the connector to join it securely to the 1/2" (13mm) pipe.
- Attach the emitter to the other end of the 1/4" (6mm) pipe. If your emitter does not have a built-in connector, you will need to use a separate connector. Ours had a built-in connector and attached directly to the 1/4" (6mm) pipe.
Stake the emitter to the ground very close to the base of the plant by pushing the spike of the emitter into the ground.
Emitter attaches to 1/4" (6mm) pipe (left)
1/4" (6mm) pipe attaches to 1/2" (13mm) pipe (right)
Emitter spike is pushed into the ground
- If your emitter is adjustable, open it a little bit by twisting the top. You can adjust the exact amount later when you get the whole system going.
Move on and repeat this process to attach an emitter for every plant in your garden.
Assemble Your Drip System
Turn on the water at the faucet, then adjust each emitter to get the water flow you want for each plant. When the flow is perfect for each plant, leave the water on for about an hour to water your garden. Voila! You now have a drip system!
If you have more than 150 plants, build two or three of these drip systems - one for each 50-75 plants, depending on your water pressure. Either connect the systems to separate hose bibs or use a splitter on a single hose bib to connect two systems to one bib. You can build as many drip systems as you need for the size of your yard. Most people's water pressure can only handle watering one system at a time, so when you water, run each drip system separately.