Hibiscus for a Water-Wise Garden
With a drip system or careful hand-watering, hibiscus are very water-wise plants!
Hibiscus love drip systems, and will grow huge on them!
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For years we have been strongly recommending that hibiscus gardeners set up a simple drip system to grow hibiscus because the slow steadiness of a drip watering system provides the best and most even form of water for hibiscus plants. In addition to this, running fertilizer through a drip on a regular basis also provides the most even and consistent nutrition to hibiscus plants, since they do best with light and frequent fertilizing.
Now with continuing drought in the southwest, and all over the west at times in the last few years, water-wise gardening has become an urgent necessity. Research study after research study has found that drip systems are by far the most water-wise systems all growers can use, from commercial farmers and greenhouse growers, to home and backyard gardeners.
Hibiscus are water-loving plants, but this doesn't mean that they need to be big users of water. They prefer a slow, steady drip of a little bit of water to huge buckets of water dumped on them all at once. Unlike lawns that require sprinkling to get all the many hundreds of thousands of tiny plants watered, shrubs and trees like hibiscus need only to have a single emitter at the base of each plant releasing a steady drip of water straight into the roots. Hibiscus, like any tree or shrub, work perfectly in a water-wise garden on a drip system. Even the lushest and most extensive hibiscus garden will use much less water than a lawn.
How Much Water does a Drip System Save?
Research has shown that drip systems use an average of half the water that a sprinkler system uses. The results of comparison studies between drips and sprinklers have shown water savings from 20% to 70% when drip systems are used with trees, ornamental shrubs, and food crops.
In addition to pouring half as much water into the ground, according to the USDA, drip systems deliver close to 100% of their water straight to plant roots. Almost none of it is wasted to run-off, evaporation, or over spray, since the drip is completely controlled, under the shade of a bush, and dripped slowly enough into the ground that the water is completely absorbed into the root ball. EPA reports estimate that as much as 50% of the water sprinklers spray is lost to evaporation, wind, overspray, and run-off!
So if a sprinkler systems uses 36,000 gallons of water annually, about 18,000 gallons will end up in the ground, and about 9,000 gallons will end up directly on the plants' roots. A drip system to water the same plants will typically use 9,000 gallons of water, and all of it will end up directly on the plants' roots. The savings is amazing! Just switching to a drip system makes any shrub or tree a water-wise plant, including hibiscus. The savings can become even larger if bark or mulch is applied around the base of each plant to shade the roots and keep the moisture in the soil for longer.
Drip systems cut both water and weeds in half!
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Is it True that Drip Systems Help Prevent Weeds?
Yes, it is true that drip systems help prevent weeds. The water goes only onto the roots of desirable plants, and doesn't spray all over to water unwanted plants like weeds. The circle of water stays small and contained, which also keeps the possibility of weeds small and contained.
A series of studies from the University of Washington compared a drip system to a sprinkler system in the cultivation of squash. These studies found that the total weed growth was 50% less with a drip system, plus the total biomass of the weeds was 75% less. In other weeds, there were half as many weeds, and they stayed smaller in the drip system fields.
Is There an Advantage to Slow Watering?
All research shows a further advantage just in the fact that drip systems deliver water slowly. Think of a torrential downpour in a huge storm. Torrents of water wash away soil, make sides of hills slide down, make gouges in smooth soil, and generally mess up the terrain. On the other hand, a soft gentle sprinkling rain that goes on for several hours doesn't disturb the topsoil or terrain at all. The water lands softly and so slowly that the ground is able to absorb each drop. A slow rain like this often doesn't even produce puddles, but it still deeply soaks the ground. A drip system is like a very gentle rain that slowly eases into the soil without tearing it up. It works on hillsides or hilly yards just as well as on flat yards.
Grow lush hibiscus plants with very little water
using a drip system
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To take maximum advantage of this, create a small well of soil around the base of each plant. Then if the drip finally does create a puddle, it will be exactly where you want it, ringing the base of the plant. It won't create rivulets or streams of water running down your hillside or giant lakes of water in your flat areas.
How Hard is it to Build a Drip System?
A drip system is the easiest type of system to set up. It is much easier to create than a sprinkler system! Even the most unhandy among us, who can barely manage a screwdriver, can manage to build a simple, manual drip system. The internet is full of step-by-step instructions, including our own Build Your Own Drip System pages.
All hardware stores have the parts you need. Just be sure to buy all your parts from the same store to make sure they match. If you don't know what you're doing, go to your local mom and pop hardware store and ask them to help you match up parts. Or go to a website like Dripworks.com where they will help you design your plan and send you a super easy kit of all the parts you need. You'll be amazed at how simple it is, and your hibiscus, your water bill, and the environment will love you for it!
Hand Watering with Wells
If you have a small hibiscus garden and just can't face setting up a drip system, hand-watering into a small well at the base of each plant is also very water-wise. Use a nozzle that you can close as you walk between plants, and use a gentle spray that doesn't wash away the soil. It's a bit time-consuming, but uses very little water.
- Mile, C.; Nicholson, M.; Sonde, M. 2014. "Efficiency of Drip and Overhead Irrigation Systems." Mount Vernon Northwestern Washington Research and Extension Center, Vegetable Research and Extension, http://agsyst.wsu.edu/IrrigationSystems.html
- "Drip and Micro-Spray Irrigation Introduction." Alliance for Water Efficiency, 'Promoting the Efficient and Sustainable Use of Water,' http://www.allianceforwaterefficiency.org/Drip_and_Micro-Spray_Irrigation_Introduction.aspx
- "Water-Saving Technologies." United States Environmental Protection Agency
, Water Sense, https://www3.epa.gov/watersense/outdoor/tech.html
- "Conservation Practices that Save: Irrigation Water Management." United States Department of Agriculture,Natural Resources Conservation Service, http://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/national/energy/conservation/?cid=nrcs143_023638.
The Dreaded Hibiscus Pest ~ Scale!
Brown bumps on brown bark
are a pest called "Scale."
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In the last month we have had several hibiscus lovers send us photos asking us what, if anything, is wrong with their hibiscus. Both photos showed raised spots on the bark of the hibiscus plant. In one case, the spots were brown and the grower told him the spots were part of the bark.
Hibiscus bark is rough, but it almost never has large round bumps on it. It has shallow, vertical cracks and crevices. But round bumps like this are rarely part of the bark. If you see one bump on your hibiscus wood, you may not need to worry. But a few days or a week later if it is 2, 3 or 4 bumps, then you have a pest. This is brown scale, a pest that will slowly but surely take over your whole plant. The photo at the right is an example of a very severe scale infestation that you never want to see in your hibiscus garden!
Brown scale on green stalks
is easier to see.
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At the first sign of a round bump or white spot like these, grab a Q-tip and Horticultural Oil. In a pinch when you only have a few bugs, cooking oil will work, although it will stain the bark. Move the plant into the shade, dip the Q-tip in undiluted oil, and cover each bump with oil. The oil smothers the scale, kills it, and it drops off the plant. Check your plant at least once a week and treat every bump until they all disappear.
Snow scale is bright white and easy to see. White flies have a similar look though. To tell the difference, shake the plant. If the white bugs fly away, they are white flies. If they don't fly away, they are snow scale. Snow scale starts on stalks, and prefers bark. White flies start on leaves and prefer leaves. With bad infestations, both bugs will cover the entire plant, so always use the shaking test to be sure.
White spots on bark
are snow scale.
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If your plant has too many scale bugs to treat one at a time, you will need to buy Horticultural Oil. Take your plants to a shady spot, or wait until evening, when there will be no sun on them for many hours. Use undiluted, or barely diluted hort oil, and paint or spray it only where the scale is. Avoid spraying or painting leaves if possible, since undiluted hort oil is hard on leaves.
Check your plants at least once a week, and keep treating until you don't find a single scale bug anywhere! When you get down to a few bugs, switch to the Q-tip method so you don't stress the plant.
Scale thrives in tropical locations, so if you live in a tropical place like Florida or Hawaii, or if you buy hibiscus plants from a tropical place, check your plants frequently for scale. Treating a few scale bugs is easy. But treating a severe infestation is very, very difficult. Knowing what to look for is the key!
If you live in California and buy plants that are grown here in California, you don't need to worry about scale. We don't have it here unless you buy plants from a more tropical place.
Seedling of the Month...
One of the goals of all hibiscus hybridizers is to develop flowers with multiple rings of color. This new seedling caught our eye because it has multiple rings, but also because the colors aren't the usual multi-colors we see in hibiscus. The flower is a large 7-9" single in rings of orange, pink, blue, light red, and white around a dark red eye, shot through with white rays.
This new seedling is the child of 'Saffron' and 'Arabian Princess.' It looks like it has inherited the gorgeous, lush bush of its mother 'Saffron' along with the faster growth habit of father 'Arabian Princess.' If further tests go well, we may have this new variety available for sale sometime in the next 2 years.
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