I grow kaffir lime trees in pots and changed the soil with potting mix a few months ago. Two of them have small fruit and the others don't. One has slight yellow leaves. Is it better to grow them in the ground rather than in pots? How do you make them bear a lot of fruit? They've been in the same size of pots for many years. Thanks, Robbie.

Kaffir lime trees are very happy growing in tubs and planters, over time the root zone can get restricted so it is wise every few seasons to re-pot them into larger tubs. When planting citrus in pots or containers, plant in Tui Pot Power, which contains a controlled release fertiliser, SaturAid wetting agent to ensure water gets to the root of the tree, water retention crystals, and Acadian seaweed to protect plants from common soil-borne diseases.

Kaffir limes do not produce a lot of fruit; they are mostly grown for their foliage which is used in Asian cooking. The fruit has some juice, but isn't used as commonly as the leaves.

They aren't tolerant of really cold weather, but in good conditions can produce fruit year-round.

Apply Seasol plant tonic now to give them a boost, and trim back any long branches to encourage some new healthy growth and fruiting wood.

Click here for our guide to growing citrus >