It's important to know how wide and deep a gardenia's root system is before moving, transplanting, or planting it. Gardenias do not like having their roots disturbed. If you transplant a gardenia in the outdoor garden, be prepared to baby it for several months until it settles into its new location.
How Deep Are Gardenia Roots?
There's no definite answer to the question, "How deep is a gardenia root system?" Six inches? Ten inches? The answer varies with the size of the plant. A mature specimen several feet tall will have deeper roots than a seedling, so there's no one right answer. Gardenias are considered shallow-rooted shrubs. This means their roots spread out and remain close to the surface, rather than grow deep down into the earth. A good comparison is to think of it in terms of a maple tree rather than an oak tree.
- If you've ever grown a maple tree, you've probably noticed the roots remain very close to the surface; you can see a network of bumpy woody roots near the base of the tree.
- Conversely, an oak tree sets its root rather straight down. You won't see as many of an oak tree's roots near the surface as you would with a maple tree.
- Gardenia root systems aren't noticeable like a maple tree. The similarities relate to the fact that the roots of both a gardenia and a maple tree branch out, rather than down, under the soil surface.
Gardenia Moisture Needs
Learning a plant's growth habits, such as how deep the roots grow, is important. This knowledge can help you properly care for a gardenia or successfully grow one (or another shrub). Knowing that gardenia roots remain shallow but grow wide can help you understand why gardenias cannot tolerate droughts and need constantly moist soil.
- A plant that sends down deep roots can survive droughts better than others. Its roots can tap into moisture far below the surface and withstand longer periods between rains. Not so for shallow-rooted plants like gardenias, which need moist soil.
- Gardenias and other plants with shallow root systems tend to need more water, especially surface water. Since the root system of plants drinks in the water and nutrients from the soil, their roots can only access the water they're in contact with.
If the soil around the roots of a shallow-rooted shrub such as a gardenia dries out, the plant will experience great stress and may even die. To prevent the soil from drying out, water frequently. Apply a thick layer of mulch around the plant. Mulch not only keeps water from evaporating, but it suppresses weeds, too.
Transplanting Established Gardenias
Gardenias should be transplanted in the fall, after they have quit blooming. They prefer dappled shade and like to grow in acidic soil that drains well and is rich in organic matter. The biggest challenge to relocating an established gardenia lies in figuring out how far the plant's roots extend out around the plant. Try a few exploratory pokes around the shrub's perimeter before digging. If you hit roots, go out even wider than the shrub itself.
- If needed, amend the soil in the planting area by adjusting the pH to be acidic and add in manure or other organic matter.
- Dig the hole for the translated gardenia about as wide as the mature shrub and about as deep as the width.
- Before digging in to unseat the gardenia with your shovel or spade, try a few exploratory pokes around the shrub's perimeter to get a sense of how far the roots extend.
- If you hit roots, go out even wider than the shrub itself to figure out where to dig. The more soil you can dig up around the plant when you transplant it, the less you'll disturb the root system and the happier the plant will be.
- Very carefully dig around the entire gardenia, then dig down as deeply as you need to in order to dig up the main root system.
- Place the gardenia in the new hole, being sure to bring some of the old soil with you to the new planting hole.
- Tamp (press) down the soil around the transplanted gardenia carefully. It should be firmly tamped into place, but not compacted.
- Water thoroughly, then apply a layer of mulch around the plant.
- Water the shrub daily until signs of new growth appear.
Note: If you need to know how to transplant a new gardenia plant from the nursery container in which it was purchased, follow most of the steps above. Since the plant is in a container, you won't have to worry about figuring out how far out the roots spread before placing it in the hole. Try to keep all of the dirt from the potting container in place around the roots when you remove the plant from its temporary home.
Gardenia Root Systems Vary
Although it may be possible to estimate the depth of a plant's roots, each plant is unique. The root system may vary among plants even within the same species. There's no way to know the exact depth of an in-ground gardenia's root system until you explore the ground beneath a particular plant. Be very gentle when repotting or transplanting gardenias. When you need to relocate a gardenia plant, dig carefully and note where the roots appear in the soil. Give the plant some TLC after moving it; you'll need to baby it through the transition. The plant may sulk and refuse to bloom the first year after moving it, but the gardenia plant should bounce back if it successfully takes to the new location.