Q.Kaffir Lime seedling just purchased
This will need re-potting shortly, as roots coming out of bottom of 8cm pot. What compost should I use? Is the plant lime tolerant (i.e can I use hard water from the tap or rain water)? What is best to use in base of pot to help drainage?
Citrus trees should be watered with clean rainwater whenever possible. Tap water is often treated with chlorine which can be harmful to lime trees. If your tap water is treated with chlorine, you will want to invest in a filter to remove the chlorine from the tap water. If a filter is not a possibility, you can leave the water you use on your citrus tree to stand uncovered for 24-48 hours before you water your tree and the chlorine should evaporate to harmless levels. If your tap water is hard (alkaline) you will want to add a tablespoon of vinegar to 1 gallon of water to lower the pH.
Placing gravel or small stones in the bottom of the container will help improve drainage. i would use a potting mix made for citrus or you can make your own with a mix of equal parts soil, sand and peat moss.
For more information on the care of kaffir lime trees, please visit the following link: