Yes, those certainly look like healthy citrus roots. Citrus feeder roots will be shallow (like avocado roots), and you'll see the majority of the little feeder roots at the edge of the canopy or a bit beyond. Why don't you post a photo of the entire tree, close up of the leaves and trunk, and let's see if maybe we can help you out a bit?

Patty S.

How deep is the mulch layer? Is the soil well drained and not over watered? Feeder roots are always very shallow, but I don't like to see so many growing up into the mulch. That can cause problems.

I hope that you can provide some good images, as Patty suggested.

Here is a picture of the tree. It is gown on a small mound with 2-3 inches mulch. The tree was planted last October. I dug a shallow hole of 4-5 feet in diameter, created a small mound and planted the tree there. The tree grew quite well in the pot with new shoots and leaves. After planted in the ground, it flowed in the spring and have some fruits growing now. It shed more than half of its old leaves and never grew any new leaves. I checked under the mulch several times and found a lot of new root growth like those in my previous picture.

I live in San Diego, it never rains in the summer. I checked the soil with a wood stick, the soil looks on dry side. I actually tried less water, more water, less fertilizer, more fertilizer etc., nothing works. This happens to all my citruses. They grow quite well in pots. But once they are in ground and have more space, they seemed only focus on growing roots and totally ignored the top. And strangely, none of my several citruses in ground died even after I gave up and stopped caring them.

I recently read "oxygen stress" on this forum and started wondering that maybe the reason. But I really don't know what to do about it since the mulch is not really thick.

If I were to go by just what you've been telling us, I'd question the quality of the soil, first of all. Does it drain well? Is it of a nice texture? What is the pH?

Did you plant the tree too deeply in the hole? Did you add a bunch of amendments in the hole and as backfill. You didn't say so, and I hope not. Is it watered by an irrigation system set on the needs of turfgrass?

Did the tree come out of the pot with a root ball that appeared to be very bound up and tight?

I think the soil drains ok, it's on a mound and there is a nearby french drain about 8 inch below the mound top. Before I planted the tree, I put it in a fabric pot for half a year. Now, the root grows far beyond the original pot area. The soil surface of the original pot is still soil surface now. When I planted the tree, all I did is mostly loosening up the soil, maybe added 10% compost bought from homedepot. The soil quality is not good. The house is a new construction and there is no top soil in the yard. But other trees grow pretty well, stone fruit trees, avocado and a Manila mango. I used two micro sprinklers watering the tree and found that the water might have trouble penetrating the mulch. I changed to 20 feet 0.5gal/6inch drip line wounding around the tree below the mulch. A little better than micro sprinkler but not much. The root is actively growing. Where ever there is moisture there is this root, if it is the citrus root. As for the top, maybe shrinking slowly.

I killed other trees, but I usually can get them growing for the second time. For citrus, it seems I can never get it right even though I have not kill any yet.

Citrus are heavy feeders and poor competitors relative to neighboring plants/grass; your tree looks a bit underfed, which is partially the cause of the prolific root growth looking for food.
Avocados are by contrast very strong competitors for food and water and will send roots out and down very aggressively to "steal" from its neighbors.

Okay, first off, there are areas of San Diego that are on pure clay. You don't seem to really know what kind of soil you have, or how it drains, and the fact that there's a french drain nearby makes me suspicious that you're sitting on clay. Before you plant any plant, especially a citrus or avocado tree, you need to determine what kind of soil you have, and what kind of drainage you have. You didn't really use a mound type of planting - that requires a much larger, taller mound, and is used for those on clay soil with poor drainage. So, let's first figure out what kind of soil you're dealing with: Dig a hole about the size of a 5-7 gal pot. Fill it with water. See how long it takes to drain. It should drain within a couple of hours. If not, (or, if it sits all night), you've probably got clay soil that is not draining well. If this is the case, you're going to want to plant on much taller mounds, and use amended soil. Next, the mulch you have around the tree needs to be removed from the trunk. It is possible your tree is planted too deeply as well. Remember, "less is more" for trees. Seeing a little of the root flare, especially with citrus, and especially in clay is a good thing :-) If you do have good drainage and you think your soil is poor, it's probably mostly DG, which is very common for us here in San Diego county (this is what I'm on.) Then, mulching regularly with compost and bark mulch will help to return organic materials to your soil. Again, keep the mulch away from the trunk. PH is not an issue for us here in San Diego county, don't worry about your soil pH. We're pretty neutral here (or we wouldn't be the epicenter of citrus growing.) Our pH range here is perfectly suitable for citrus, so no worries there.

Next, you should water deeply about once a week. Check your soil moisture with a stick. I use one of the cheap green plastic covered stakes from Lowe's. You should be able to insert the stick 18" or so. If you can, then you're moist enough. If not, or if you can see your trees are visibly dry, then water. It sounds to me like you're only surface watering, which would account for so much surface roots in the mulch. Create a nice well around your citrus at and beyond the drip line. This is where the water should accumulate from your microsprinklers, allowing it to pool and then percolate down.

You should also be applying a good quality granular citrus fertilizer 3 to 4 times a year, as John has mentioned. I apply in Feb, April, June/July and then in Oct.

Patty S.

Thanks Patty and everyone, my soil is compacted clay because of the new construction site. It doesn't drains well. A larger mound won't fit well in my small back yard. I will try to remove mulch around the trunk, add some more fertilizer, and deeper watering.

BTW, the French drain was added by our landscaping contractor when we moved here two years ago. French drain seems like standard for those contractors. They are every where.