Potting or repotting hibiscus is a rather simple and straight forward task. However, there are a certain few points to keep in mind as follows:

Recognizing when to repot:

Basically this is a matter of observation. If you see roots coming out the drain holes in the pot (upper right photo - roots coming out of drain hole), this is an indication they are seeking more room and its time to repot (lower right photo - slipped out root mass). If uncertain, tilt the pot and slip the root ball out for observation. If there is a solid mass of roots and particularly if they are spiraling around the bottom, it is time to repot.

Here you have two choices. If you want the plant to get larger, then select the next pot size larger. For example, if it is growing in a 6" pot, you would go up to a 7" pot or maybe 8" but no larger. Over potting, meaning that one places the new plant in a much larger sized pot, is dangerous. As the excess soil will have no roots for a time, it can sour (develop undesirable microbes) which can lead to the demise of your plant.

This is particularly true in cold, wet conditions that favor the development of detrimental soil fungus. If done in warmer weather, the plant will spend most of its time growing into the new potting mix and will likely bloom less.

If you would like to maintain the plant in the same size pot, this can be accomplished by pruning off 1/3 of the roots from the bottom and sides of the root ball and 1/3 off the top of the plant. It can then be placed into the same sized pot, replacing the removed root mass with new potting mix. If done yearly, a hibiscus can be maintained almost indefinitely in the same size pot. However, one must not try to do this with too small a pot. Generally, a 5 to 7 gallon pot is required for mature plants if they are to bloom normally, but they can be maintained in somewhat smaller pot sizes depending upon the variety selected. Some are naturally low growing, making them suitable to pot culture, while others can become massive and will barely subsist in a pot of too small a size (upper left photo - selected new pot beside old one).

Selecting a pot type:

As drainage is very important, select a pot that has large drain holes, preferably which are at the bottom on the side as well as underneath the pot. (right photo - positioning plant in selected pot). If they seem too small or few and the pots are of plastic, the holes can be enlarged with a cutter or a drill. As propagated hibiscus do not have tap roots, which are found only in seed grown plants, a normal pot profile with only a little less girth than depth is fine. In other words, it is not necessary or even desirable to have a tall narrow pot. If the potted plant is to be placed in full sun, to prevent over heating, it is best to get white pots, and in this respect brown would be preferable to black. As white pots are difficult to find and may not suit your taste, to protect the root mass from the effects of too much heat, one can place the potted plant inside an empty and slightly larger pot. This provides an insulating air space. Should you live in a climate which is too cold in the winter to leave your hibiscus outside, these larger pots can be planted in the ground and the plant in the smaller pot can be set inside, which also stops it from falling over in high wind and makes it easy to remove when the necessity arises.

Selecting a potting mix:

Generally, one of the most important factors is to choose a mix that drains well. Most commercial mixes are adequate and hanging basket mixes having even better drainage characteristics making them suitable for this purpose. Should you have a mix that seems heavy (very absorbent) it can be lightened up using additives like perlite. One can also make their own potting soil using a basic formula of 1/3 normal garden soil, 1/3 sharp sand (crushed as opposed to river sand) and 1/3 media rich in organic content, e.g., composted stable cover (mixture of sawdust and horse manure), composted organic material such as leaves and waste, or even peat moss.

Again the important thing is that the soil drain well, and this can easily be tested by placing the soil in a pot and watching how rapidly water passes through the pot. Once the pot is filled to the rim with 1 or 2" of water above the soil level, it should soak in and pass through the pot within a minute or so. If the water remains is the pot much longer, it is too heavy and needs to belighted up with an additive such as perlite, more sand, etc. pH or the soil acidity is important as well. Normally you won't have to worry about it, particularly with commercial potting mixes, but if you want to be specific, arrange to have your soil slightly on the acid side, i.e., 6 to 6.5 - 7 is neutral and higher is consider to be too basic. Peat moss will acidify a soil mix and dolomite or horticultural lime will raise soil pH. If the pH is too far out, the plants efficiency in absorbing nutrients is diminished.

The Mechanics:

Normally one will place enough new potting mix at the bottom of the pot, so that the root mass will permit the surface to rest about 2 to 4" lower than the pot rim One then simply adds soil around the edges and perhaps just a bit on the surface. Shake or tap the pot well so that the potting mix settles in and fills all air spaces. The plant should then be watered and placed in an area with less than normal light until it has had a few days to establish itself.

Fertilizing:

Fertilizer can be added to the potting mix or placed on the surface of the mix in the pot (upper left photo, with fertilizer applied). Generally, it is best to let the plant become established before fertilizing, but this is only really essential if the roots have been severely disturbed. If one is planting a bare root hibiscus, where all the soil has been removed, no fertilizer should be added until new leaves appear. Bare rooted hibiscus are severely set back, often losing all their leaves and growing new ones a week or more afterward.

Mulching:

As hibiscus derive a considerable amount of their moisture and nutrition from a mass of tiny feeder roots just below the soil surface, particularly in pots of larger size, it is important to place an inch or two of mulch material on top of the potting mix. Smaller, dried, tree leaves; bark; ceramic beads made for this purpose, etc. can be used. Mulch will serve several purposes. It insulates the soil and helps reduce overheating, it maintains a moist humid environment conducive to the development of the fine feeder root; it reduces excessive evaporation; it reduces or eliminates the problem of weeds establishing themselves in the pots; and, it generally provides for improved plant growth conditions (right photo - soil shaken into pot and mulched).

Watering:

By adding 1 to 2 inches of mulch, there should still be about 1 to 2 inches from the surface of the mulch to the top of the pot rim. This permits one to fill the pot with water to the rim without overflowing the mulch. Generally, particularly with large pots, it is best to fill all of the pots to the rim and when the water has disappeared repeat once again. If this is not done, frequently the water passes around the root mass and out the bottom, only saturating about half the potting mix. The second watering assures that the soil is saturated and assuming you have a properly draining mix, the excess will pass through rapidly. For this reason, do not place a tray under the pot that retains the water. This would cause the potting mix to be overly saturated and can cause root rot. The only exception would be in very hot weather, where the plant can use this reservoir of water to tide it through the day or until the next watering, but care must be taken that all the water is absorbed in a matter of hours. When over-wintering plants in cool conditions, with lower than normal levels of light, it is important to water very sparingly. Failure to do so will result in root rot and loss of the plant (upper left photo - a 4-year old repotted Georgia's Pearl in a 5-gallon pot).

Happy Hibiscus Growing To All
Dick Johnson, Tahiti