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While the flowers on these pages may be very enticing, you may look out your window, see snow and ice, and wish you were living in south Florida, Hawaii, Singapore or some other tropical area where you could grow tropical hibiscus.

 Tropical hibiscus need a lot of light to bloom and perform well. Full sun from dawn to dusk may be too much during summer, but during short winter days, they need all the light they can get. Even with a lot of light and ideal temperature and humidity during the winter, they will likely bloom and grow less.


Before we get into it, many people want to know, "How do I tell if I Have a Hardy Hibiscus or a Tropical Hibiscus?" and "Will My Hibiscus Overwinter Outside?"

You need to know which one you have. Unfortunately, garden centers, nurseries and home improvement centers lump all hibiscus together.

If your hibiscus has glossy deep green leaves, 3-6" flowers of red, pink, orange, yellow, double or single flowers, it is probably a TROPICAL hibiscus. While many common garden varieties have the 3-6" blooms, many of the hybrid varieties of tropical hibiscus can have blooms around 10" in diameter under ideal conditions.

Another way to check is if the flowers are salmon, peach, orange, or yellow, or double flowered, then you probably have a TROPICAL hibiscus. Hardy hibiscus do not come in these colors or in doubles! Many tropical hibiscus flowers have more than one color in a bloom either in bands or as spots.

If your hibiscus has dull medium green heart shaped leaves, dinner plate sized white, pink or red flowers with HUGE, bomb shaped buds (2-4" in length!), it is a perennial, hardy hibiscus.

Hardy hibiscus need very little care over the winter, they are root hardy to about zone 5 with no protection. They die to the ground each year.

If you have a tropical hibiscus, remember it is a TROPICAL. They will not tolerate more than a night or two of light freezes. Even one hard freeze (below 25) could kill the plant. These plants are native to sunny, warm and usually humid tropical places.

They detest cold, rainy weather and cold, wet soil. They will not reliably survive outdoors north of zone 9. In all other areas, it may be a good idea to bring them indoors BEFORE temps regularly drop below 40-45 F at night to avoid any damage.

Treating your tropical hibiscus correctly will give you years of enjoyment. But remember, they are not immortal! Some are spent after 4 or 5 years in a pot and should be tossed away at this point. Try some of the many and never ending new hybrids being developed!


Getting Tropical Hibiscus Ready to Come Inside in the Fall/Overwintering Indoors

If you want to keep your hibiscus and grow them again the next season, you will need to bring them indoors before the night temps drop much below 40° F. They will need  a bright or sunny area, or under fluorescent lights. The optimum temperatures indoors seem to be between 55 and 70. The cooler end of that temperature  range will produce far fewer insect problems later in the winter. If they are kept in a greenhouse, keep them cool (55-65) and water when they are dry.

Ideally if you want to bring your hibiscus indoors to over winter them, they should be grown in pots outside all season, not planted directly in the ground. The problem with planting in the ground is that when you dig them up in the fall, they are weakened by yanking them out of the ground and many times they will rot before they produce new roots in a pot. They should be kept in relatively small pots for years (10-14" in diameter is fine). You can even sink the potted plants in the ground in summer and then just pull them up , pot and all in  the fall, wash off the pot and bring it inside easily with no shock to the plant in fall.

  • Before you bring them inside, cut back your plant(s) quite a bit, to within 4-5" of the main stems. This does a few things: it will help eliminate the bugs and insects that hide in the plants BEFORE they get inside. They like to hang out in the tips of the branches, in the newest growth. Also remove any dead leaves, stems., old flowers or debris in the pots, or on the plants. 
  • If  you want the best chance of having healthy, vigorous plants with flowers next summer, your plants need to rest  indoors during the shorter days from October till Feb. or March. DO NOT push them to keep blooming indoors and leave them full of old foliage.
  • After cutting back your plants, but before they come inside, be sure and hose them down , making sure to blast the stems, under the leaves, etc. Let them dry thoroughly and bring them inside. This will eliminate the need for any insecticide at all. if you must spray, insecticidal soaps and neem oil work well. Drench the upper and lower parts of the leaves, as well as the stems and let dry thoroughly outside for a day or so before they come inside.
  • The leaves will probably turn yellow and fall off when  the plants are brought inside, this is normal. They will regrow when they are ready. In  the meantime, water very sparingly! Do not keep the soil wet. It is best to let the soil become almost bone dry before soaking it again. Do not let any water sit under the plants in saucers, etc.
  • Your plants will rest and may not produce new leaves until late February or March. This is normal too.
  • Realize that many times, hibiscus never bloom well again after the 1st winter inside. There is not much you can do about this. It appears that the generic grocery store, Costco, Home Depot, etc., hibiscus tend to not bloom well again after the 1st season. The new large flowered hybrids seem to perform much better year after year. This is an observation based on my experiences over wintering hibiscus. Your hibiscus experience may vary.
  • The other option is to buy some new hibiscus each year, enjoy their prolific flowers for the summer and toss them in the fall. That way, you are guaranteed lots of flowers each summer.


There are people who grow these plants year 'round in the northern U.S. and Canada, Sweden and NOT using green houses! Unless you take some extra steps, such as using artificial lighting, you can't expect the same lush growth and bloom quantity when your plants are spending their winters inside and under less than tropical conditions. But, they will be ready to reward you for your efforts once they are outside again and the warm weather arrives.  (However, if you do have a greenhouse...)

If you aren't too far north, building this will help and is easy to do.

There are reports of another way of over-wintering these tropical plants.

 
Tropical Hibiscus and Their Environment: Gimme Shelter
Insect and Disease Problems: Don't Bug Me, I'm Already Sick
Watering and Moisture Tips: Water You Doing to Your Plant?
Potting and Containers: The Heart and Soil of the Plant
Repotting and Fertilization: Feeding the Masses
Getting Ready for Summer: Living in Paradise
Winter Care: A Shower a Day (or at least occasionally), Keeps the Aphids at Bay!

 

Tropical Hibiscus and Their Environment: Gimme Shelter

Since several hours of temperatures below freezing can be deadly to hibiscus, before the mercury drops, growers move their potted plants to an inside location where they will get, perhaps, 3 or 4 hours of direct sunlight a day. (Supplementing with artificial light (please visit) may also be an option.) Here they will stay for a few months. Some leaves may turn yellow and drop and some buds may fall during the adjustment period. If chemical sprays are used to control insects, these need to be used before the move.

Feel free to prune your hibiscus to fit the space where it be indoors. It is not important WHERE you make the cuts, as long as they are made cleanly with a sharp pruner. Just remember that you will not see much (if ANY) new growth from this pruning.The hibiscus growth slows down considerably during the late summer/fall and winter.

This is also a good reason NOT to repot in the fall. The hibiscus will not generate new roots easily at this time of year and will probably suffer from root rot before it gets re-established.

Insect and Disease Problems: Don't Bug Me, I'm Already Sick

Once inside, soaps, such as castile and Murphy Oil Soap or unscented liquid dishwashing detergents such as Dawn are used in a one tbspn per gallon of water solution. Soaps are probably more effective and work differently from detergents. Big pots are recommended. Nothing smaller than a 10" pot. Using 14" pots, hibiscus have been known to thrive for almost 10 years.

Watering and Moisture Tips: Water You Doing to Your Plant?

Don't over-water, keep on the dry side, but remember that indoor air may have a drying effect because of low humidity. Misting the leaves at least daily is desirable in most instances. It may also be helpful to place each pot on a large tray containing gravel. Fill the tray with water up to the top of the gravel. As the water evaporates from the tray, humidity will be higher around the plants, especially if they are not in drafty areas. Humidifiers are also beneficial.

A small plant with few leaves needs much less water that a big leafy plant. Do NOT over-water! 

Potting and Containers: The Heart and Soil of the Plant

The soil in pots is very important. The usual "potting soils" are not recommended. They can be much too heavy and can harden with a few waterings. One recommendation is to use a light soilless mix such as PRO-MIX or Sunshine Mix which is available at most nurseries/garden centers. These are soilless mixtures consisting of perlite, vermiculite, peat moss, with some bark. Jungle Mix, a professional seed starting mix, available from some home/garden centers, also produces good results. Remember that tropical hibiscus do best with very good drainage.

Repotting and Fertilization: Feeding the Masses

In late winter, scrape off the top 2 inches of old potting soil and replace it with fresh soil. You do not have to be gentle; you will be scraping old roots, too. Go for it! Then add Osmocote slow release fertilizer "for indoor plants" per the label instructions. At this same time, prune as severely as you like, using sharp, clean pruners and just above a node. Occasional use of a 20-20-20 water soluble fertilizer is also appropriate. The plants will respond beautifully to this treatment.

Getting Ready for Summer: Living in Paradise

Once the night temperatures are consistently above about 55° F (13° C) or so, you can think about putting your hibiscus outside again.

Here's a quick list of things to remember:

• gradually expose your hibiscus plant to the outdoors. Place your plant in a shady or protected spot for a few days and then gradually increase the amount of direct sun it receives each day for about 10 days or so. After that, you can move it to it's final sunny summer spot. If you don't do this, your hibiscus leaves will fry and sunburn, just as you would if you were out in the hot sun for 8 hours without sunscreen after being indoors all winter.

• prune your plant now if you wish to change the shape or height or induce a bushy flowering plant.

• this is also the time to refresh the soil or repot your plant if needed (rarely- they love to be potbound!)

• once outside, spray down both lower and upper leaf surfaces with the garden hose to remove any indoor dust or bugs. You 'll be amazed how it rejuvenates your plant.

• after your plant has been back outdoors for 2 or 3 weeks, you can start to fertilize again with your favorite fertilzer.

• avoid saucers with standing water under your hibiscus plants- they can cause root rot and leaf drop.

It's perfectly normal for your plant to have yellow leaves or even drop some leaves in response to the stress of going back outside.  Different varieties of hibiscus may  have their own "personalities" and may not perform uniformly when conditions change.

If you follow these general guidelines, your plants will be happy and thrive for many summers.

 

Winter Care: A Shower a Day, Keeps the Aphids at Bay!

During the winter indoors, most hibiscus may develop a problem with aphids or white fly. One of the non-chemical ways to help with this is to give your hibiscus a shower!

Cover the top of the pot snugly with aluminum foil or heavy plastic (to keep the soil from washing out and making a mess, also to prevent waterlogging the roots) and make sure that you completely seal off the pot around the stem. Then just stick the plant pot and all in the shower, turn on a low to moderate spray directly on the leaves. Use lukewarm to comfortably warm (NOT HOT!!) water.

If you have a movable shower head or attachment so much the better. Be sure and try to get the undersides of the leaves if you can. You can even turn the pot on its side if you seal the top of the pot with the aluminum foil good and tight (use rubber bands). Do this for about 5-10 minutes.

This may sound extreme, but it sure gives your tired, dusty, buggy plant new life. Even if you do this only once or twice during the winter, you will notice a difference.

It will not eliminate the pests but will certainly control them and your hibiscus will thank you.

 

If you have questions on these recommendations, you can direct them to the source, Boca Joe, for most of the above information.

 

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