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Garden Guru

Fall and Hibiscus

Jim Boxberger
Posted 10/15/21

It never fails in the fall when the leaves start falling, that I will have customers come in worried that their evergreens are starting to die, because the needles are starting to yellow and fall. …

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Garden Guru

Fall and Hibiscus


It never fails in the fall when the leaves start falling, that I will have customers come in worried that their evergreens are starting to die, because the needles are starting to yellow and fall. This is a normal occurrence and you don’t need to worry about it.

Every year evergreens will drop approximately one-third of their needles as they will store that energy in their roots to push out new growth in the spring. The pine trees are a perfect example of this right now as they are quite yellow right now. As long as your evergreens are only losing their interior needles you have nothing to worry about.

Also if you haven’t done it already, it is time to get your houseplants brought back inside for the winter. Last week, I had a customer come in and ask if she should bring in her hibiscus inside for the winter. I had to ask which type of hibiscus it was and I got a “deer in the headlights” look as she had no idea there was different types of hibiscus, which is more common than you might think.

What was worse is she had no idea what type of hibiscus she had. So I had to play twenty questions to find out which type of hibiscus she had, so that I could give her the proper advice. There are three basic groups of hibiscus: 1. Tropical 2. Perennial or 3. Woody Shrub.

The first group, the tropical hibiscus are some of the most beautiful hibiscus like the ones you would see in Florida or Hawaii, would definitely need to come inside before frost. These hibiscus are typically only hardy to Zone 9 or 10 which means they can’t handle temperatures below 20 to 30 degrees above zero. So these will have to come inside for the winter and should be placed in a southern exposure window in the house.

One note, these hibiscus will usually drop most or all of their leaves during the location change. This is a natural occurrence, not to worry new leaves will start to grow in a week or two. This leaf drop will also occur if you re-pot your hibiscus into a larger pot as well. If you want to fertilizer tropical hibiscus, use a mild liquid fertilizer in the fall and a stronger liquid fertilizer in spring like Foxfarms Tiger Bloom.

The second group, the perennial hibiscus, grow and flower each year, but they die back during the winter and re-grow from the roots in the spring. These hibiscus should be cut back to about three or four inches from the ground after the stems turn brown in the fall. It is also a benefit to the plant if you mulch them in for the winter as well, as this will protect the roots from freezing and thawing multiple times in the fall and spring.

In the late spring new growth will shoot up from roots and by late summer these Hibiscus will produce dinner plate size blooms. This type of hibiscus needs to be planted in the ground, they will not survive indoors over the winter as they need a dormant period. For this type of hibiscus, giving a little triple phosphate fertilizer and lime in the fall will help to produce the giant blooms that they are so renown for.

And the third type, the woody shrub hibiscus commonly known as Althea or Rose of Sharon. This type like the perennial type need to be planted in the ground outside to survive the winter. But unlike the perennial that dies back, the shrub type forms into a nice bush or depending on the pruning you can turn them into a tree.

The Althea type of hibiscus are so versatile that Sullivan Renaissance placed them on their 2013 plant list for their drought tolerance, deer resistance and late summer blooms. This type should also be fertilized and limed in the fall for the best blooms the following year. So after the game of twenty questions we determined that her hibiscus was indeed tropical.

So I informed her that it should come indoors and a few precautions should be taken. First to prevent insects getting a free ride inside for the winter I advised her to use some systemic insect granules in the soil that is in her planter. This will get rid of fungus gnats, spider mites, aphids and countless others. This should be done for all none edible houseplants before they come in for winter or else these plants can bring in plenty of harmful pests that will go after all your interior plants.

An ounce of prevention is worth a pound of cure. And don’t wait too long before bringing your plants inside. Utah had twelve inches of snow in a four hour period this past Sunday during a marathon and 87 runners had to be rescued by snowmobile.

Winter will be here before you know it.


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