Growing Citrus In Containers:
Up Potting –
Select the largest container that fits your needs, I recommend up potting into a container no more than 3 times larger than the original container. I would up pot a one gallon tree into a three gallon container and a three gallon tree into a ten gallon container. Eventually, your citrus should find a permanent home in a 15-gallon (or larger) container if you expect the tree to produce an adequate number of fruit. When repotting, please understand that your tree is going to put energy into growing roots to start filling out the pot. While it focuses on roots, you may notice a stall in branch growth. So be prepared to be patient if it seems like your tree is healthy but isn’t growing – this may very well be the explanation.
Use a well draining potting mix of your choice. Add some mix to the bottom of your container, then carefully remove your tree from its original pot taking care not to disturb its roots. Please do not bare root these trees. They are currently in the highest quality potting mix they can be, it will do much better if you leave the root ball alone than if you attempt to remove all of the mix.
Place the root ball into the new pot and plant at the same depth it was planted in the original pot. You may need to add mix to raise it or carefully ruffle the bottom of the root ball to lower it. Then backfill with more potting mix, pack lightly and water deeply. Make sure the pot is full of mix and mulch if desired. Place the tree and pot in full sun to partial shade.
Watering –
Water deeply when watering, continue to water until excess water is draining out of the pots drain holes. This ensures the tree is getting water throughout its entire root zone. When the top 2 inches of mix feels dry, water deeply again. Keep in mind that trees in a container will need more frequent watering than those in the ground, and this is especially true if you use terra cotta containers. Monitor the tree for changes and continue to water on the schedule that seems to work well for you. You may need to water more often if the weather is hotter and do not rely on a light rain to provide enough water for your tree. If you have a lot of rain you can cover the top of your pot with a white trash bag or something else to reduce how much water gets into the pot.
Fertilizing –
I recommend a high nitrogen fertilizer until your tree is established and the size you want it to be. I use a 13-6-6 fertilizer that I have had very good luck with. Follow the instructions that came with your specific fertilizer and with containers you can likely fertilize throughout the entire year.
Pruning –
Pruning citrus trees in containers is going to be important so you are able to create a tree that has dense enough branching to allow you to get a good yield but is also of a size / shape that you can maintain and move indoors if you need to for the winter. Because everyone’s needs are going to be different, I recommend you do some additional research on pruning citrus in pots to see the different variations available and choose the one that will work best for you. I do recommend removing early developing fruit off of the tree for the first couple years to allow the tree to focus more energy on growing branches and roots. If you want to leave a couple fruit on, it won’t hurt too bad, but remove most.