First a disclaimer in the way of recognizing the benefits of controlling weeds and grass around citrus trees. I think we all know citrus feeder roots are very shallow and grow in the same zone as grass and weed roots. When we fight over resources, someone is going to come up with a short stick or maybe not even survive. We know who will win if a weed is involved!

Here are a couple of resources explaining the value of, and why, we should control grass and weeds around our citrus trees:

From Master Gardeners of Ventura County, CA: If you want good growth, it is imperative that weeds are not allowed to develop near your trees. Keep the space clean for a full six feet from the base of your tree. Allow no weeds or grass to grow in this area and apply no systemic weed killers that may be absorbed by the tree roots. Mulching (keeping it away from the trunk) can be very effective at controlling weeds

From the University of Florida Extension Service: There are various reasons for following good weed management practices in citrus groves. Weeds compete with trees, particularly young trees, for water, nutrients and light, with climbing vines easily covering larger trees if left uncontrolled. Good vegetative growth and the attainment of early productivity is partially attributed to the timely elimination of weed competition. Weed growth around tree trunks and canopy creates favorable conditions for the development of fungus diseases such as footrot and brown rot (on fruit).

So now let's look at some examples of the havoc weeds and grass have wreaked on my poor neglected citrus:

A meyer lemon

A kumquat

Another kumquat

A Satsuma orange

A Ponderosa lemon

Another Satsuma orange

Clearly, it's possible to ignore the weed and grass control advice from pretty much every guide on how to grow citrus and still have healthy citrus and lots of fruit.

Am I advocating that grass and weed control advice is just a bunch of hogwash? Not hardly.

I resist applying herbicides around my trees, grass and weeds ultimately overcome mulch, and hand pulling grass is just not an option since I have a lot of trees. Someone here (thank you greenman) recommended putting down cardboard with holes in it to allow water to drain through and then mulch on top of the cardboard. That seems like a pretty reasonable option but I like to add some manure around my trees now and then and I'm not sure how to apply that type of amendment over cardboard and mulch. I think I need to put the manure in contact with the soil so it promotes microbes and earthworms. I'm not just adding N-P-K here.

Here is something I'm trying with a Ponderosa seedling I transplanted:

The tree is in a drier part of the yard so I'm hoping the wood chunks will help retain moisture. I also expect it will block out grass long enough for the tree to become established, and I think I'll get a bonus from all the bugs eating the wood and pooping in the root zone. This also won't work for all my trees but I do throw dead branches and other wood chunks left from other hobbies under a fig tree to rot.

I have also tried using some recycled round rubber mats made for the purpose. They certainly worked better than nothing but I ultimately got tired of messing with them. I had to remove them in wet weather since the center opening for the tree trunk was overly restrictive and I believed it encouraged trunk fungal disease on a couple of my more susceptible trees...namely the sweet lime.

Maybe I would go broke buying fertilizer if I were trying to make money in a commercial operation but until I find a better option, I'm going to continue to neglect my poor starving trees :>)