Q. I have a small lemon tree, about 3 ft. high and 5 years old, growing on my patio in a whiskey barrel. It currently has two lemons growing on it due to the fact that a critter ate all the others. It has produced since the second year (up to 8 lemons) if the critter does not eat them. However, the leaves on my little tree are very sparse. Is this common or am I doing something wrong. I read your blog all the time.
A. Thanks for reading my blog and you will see this posting in it soon. When we grow things in containers or pots we have to be worried a bit about the soil “going bad” over time. So if you are not adding compost or trying to renew the soil in some way it will start to get depleted or it will lose its “vitality”.
I assume you are adding some sort of fertilizer to the soil to help the tree but the addition of just a fertilizer will not be enough. Organic matter will be needed as well. It is probably best once every year or, at the most two, that you remove some of the soil from the container and add composted soil.
It is okay if you damage some roots in the process. They will grow back. But my guess is that the soil is starting to become exhausted. If you could replace that soil with composted soil or a soil mix with a good compost in it I think you will see some improvement over time.
Pick a spot in the container, take a garden trowel and dig two or three holes about halfway down and replace this soil. When you pick a compost, pick a good one. It will not be cheap. My guess a good one will run you about $20 or so for a couple cubic feet of compost.
Kelloggs makes some lesser expensive composts that may be okay. Fox Farms makes good compost but it is expensive. Look for Happy Frog or others that are similar when you do this. Replace more soil the next year in the same way.
When containers are used for vegetables or things like strawberries we normally replace the soil after a couple of plantings. Disease and insect problems accumulate and build after a few plantings. It will help if you can cover the soil in the container with a couple of inches of organic mulch that decomposes as well. I hope this helps.