Citrus plants should be repotted in the spring before new shoots appear or in early summer when the first year’s shoots are established. Newly purchased citrus plants such as tangerines, oranges and lemon trees also benefit from being moved to a suitable container. For one thing, they are often in pots that are too small, and for another, nurseries often use a peat-rich potting soil, which the plants don’t like very much.
When to repot citrus plants?
Citrus plants do not need a larger container every year. A new pot is advisable only when the roots permeate the soil like a dense web. Young plants should be repotted about every two years, older citrus trees every three to four years. Old, large citrus plants are generally not repotted. Instead, the top layer of soil in the pot is replaced every few years. For this, carefully remove the soil with a hand shovel until the first thicker roots appear, and refill the pot with an equal amount of new citrus soil.
How big should the pot be?
Many amateur gardeners repot their citrus plants in containers that are too large. This is fundamentally wrong, because it prevents a uniformly dense root ball from forming. Instead, the roots pass through the new soil and branch out only at the edge of the pot. The new pot should therefore have a diameter that is no more than five centimeters (2 in) larger. Rule of thumb: If you place the root ball in the center of the new plant pot, it should have two finger widths of space on each side.
What kind of soil do citrus plants need?
In addition to humus, commercially available citrus soil also contains a high proportion of mineral components such as lava chippings, limestone or expanded clay. Stony components guarantee that the roots are well supplied with oxygen even when the soil is wet. Since manufacturers are usually rather sparing with the mineral ingredients for weight reasons, it does not hurt if you enrich the purchased soil with some additional coarse sand or lava grit. Important: Cover the drainage holes at the bottom of the new container with shards of clay and fill in a layer of expanded clay as drainage before the actual substrate.
What you should also consider when repotting
Before repotting, carefully loosen the outside of the root ball with your fingers and remove some of the old soil. Then place the plant in the new pot so that the root ball surface is about two centimeters below the edge of the pot. Fill the voids with new citrus soil and gently press it down with your fingers.
Note: Do not cover the surface of the rootball with additional soil if the plant is too deep in the pot! Instead, you will need to take it out again and fill in more soil at the bottom.