Kaffir Lime Care – In a Planter
by Kasma Loha-unchit
11. Growing Kaffir Lime in a Planter
Many people inexperienced in container gardening make the mistake of placing their newly acquired kaffir lime plant in as large a pot as they can accommodate on their patio, thinking that the plant will grow into the pot and will then live there permanently. This is generally not a good idea. The root system of the plant is still small and when it is constantly surrounded by wet soil that does not dry out quickly since there's nothing there to use up the moisture, it becomes very susceptible to root rot. Often the top of the soil may feel dry, which prompts you to water the plant, but is soaking wet beneath the roots. The size of the planter should be proportional to the size of the plant if you are to avoid the problem of over-watering the plant.
Always pot up in a planter just one size bigger. If your kaffir lime plant comes in a 1-gallon container, you can probably keep it in that size container for a few months, or even a year, until it has shown some significant top growth. Then you can pot it up to a 2-gallon-size container and keep it in that container for a year or two, or until the plant puts out enough growth to warrant repotting into the next size pot. Eventually you'll have your kaffir lime tree in the maximum size container in which you wish to grow it. From then on, you should prune your tree regularly to a size that is proportional to its root system. This balance between the root system and the top growth is important to maintain the health of the plant, giving it the strength to withstand occasional bouts with sudden heat waves or freezing weather. A healthy plant also will be less likely to be attacked by insects and fungal diseases.
The type of planter you place your plant in, whether it is made of plastic, wood, terra cotta, or glazed ceramic, makes a difference in the type of care you give the plant. Plastic and glazed pots hold moisture longer, which means you won't have to water as frequently, but the roots can be hotter in the summer if the pots are dark in color and exposed to all-day sun. Hot roots and too much moisture can cause root rot and other fungal problems. Terra-cotta pots, on the other hand, are porous and allow moisture to seep and evaporate through their pores. The outside of the pots stay moist, moderating the temperature of the roots from too much fluctuation through the day. This evaporation also creates surrounding humidity for the plant. You are less likely to over-water a plant in a terra cotta container than a plastic or glazed one as the water drains out not only through the drain hole in the bottom of the pot but some of it also through the pores. Wood planters work similarly to terra cotta but generally do not last as long.
Whatever planter you select, make sure it has a large drain-hole on the bottom. Place a curved piece of broken terra cotta over the hole with the curved side up before filling with potting soil. This way you won't lose as much soil through the hole over time with all the watering while at the same time allowing the water to drain out. You will also prevent compacted soil over time to clog up the drain hole.
It's even better if your container has three drain holes. You can drill extra holes with an electric drill. There've been occasions when a vigorous plant has plugged up a drain hole with its roots and drowned itself during the frequent winter rains without you even knowing it. So if your plant has been in the same container for years, you might want to tip it over every once in a long while to make sure no growth is coming through the drain hole that might block drainage. If there is, simply cut back the root before it gets thick and woody. Pruning back the plant regularly to be proportional to the size of the container will usually keep the roots within bounds. A tree generally produces the roots it needs to support the plant growth, so when your plant grows too large for the container, the roots will want to break out of the container somehow and the drain hole is the easiest route out.
Always use a good potting mix with plenty of organic matter to make it well draining. Don't just buy the cheapest brand. Not all potting mixes are created equal. Search for a reputable organic potting mix at a reputable nursery. Never ever use garden soil for any plants grown in a pot. It is too heavy and the particles too fine to drain well in a planter with only a small drain hole. Plant your tree with the trunk a little above the surrounding soil to protect the crown of the plant (point where trunk meets soil) from excessive moisture which could be detrimental to the health of your tree. Water immediately after planting to settle the soil around the rootball. I like to add a few drops of "SUPERthrive!" (a vitamin and hormone booster available at most garden centers) to the water, which really does help the plant recover quickly from the trauma of transplanting.
Try to do your transplanting in the late afternoon when the sun is no longer on the plant, or in the early evening This will give the plant a chance to settle in to the location and container and rest a little from the trauma of transplanting before the hot sun hits it the next day. You can also choose to do the transplanting on an overcast day, or if you simply don't have time to do it but on a sunny morning or afternoon, then it's important that you place the planter in a shady corner and wait until evening to move it to the sunny location you intend to grow it. (Read the section "Buy and Plant Your Kaffir Lime Tree During the Warm Months" above for information on acclimating your plant to the location before transplanting.)
Because the rootball of a container plant is entirely above ground, it is more exposed to the elements than one that is grown in the ground. It will be colder in the winter and hotter in the summer and the great fluctuation in temperatures can affect the health of the plant. In the hot summer, you can move your plant to a location where it can receive some shade during the hot mid-day sun. In the winter, you'll want to move it to a location with as much sun as possible, such as against a south-facing wall. In damp, cold weather, air circulation is less critical than in dry, hot summer heat; besides, there always seems to be more than enough wind every time it rains. In frost-free areas, it doesn't even need to be a south-facing wall; any wall of the house will provide some warmth to the plant to see it through the winter. Placing the container under the eaves of the house will also keep the plant warmer and drier (which it prefers when it is cold) since it won't be continually drenched by rain, but you'll need to check on it every once in a while to make sure the soil doesn't completely dry out. If you have a lot of other container plants on your patio, you can surround your kaffir lime container with the other containers to give it a little insulation.
Although experts will tell you that you can grow a kaffir lime tree in a container indoors, I do not recommend it as you are not an expert and your tree will likely be very susceptible to insect problems due to poor air circulation and low humidity levels inside the house, especially in the winter when the windows are closed to keep out the cold and the heater is on which dries out the air. If you do move your kaffir lime plant inside the house for the winter, you would want to place it in an unheated room, near a bright, sunny window which you would want to crack open a little during the day time to provide air circulation. You can also provide supplemental air circulation with an electric fan. Do not point the fan directly at the plant, but at a wall or the ceiling to bounce the air onto the plant. You should be able to see some of the branches or leaves softly swaying to the gentle breeze from the bounced air.
If you would like a copy of this article in Adobe Acrobat (PDF) format for your own personal use, please contact Kasma.
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