I back up my mound of dirt with a wall of milk carton cardboard. Work great. While my tree is in a pot, this will work well for in ground trees.

Steve

Mulch will help.

Water it gently, underneath the drip line. Try not to disturb the mound. I know, sounds silly, but I changed my watering ways and no longer have your problem.

gentle watering will definitely leave mound alone but when mine gets disturbed, I just rearrange with my hands, no biggie

you can build a raised bed around your tree with either lumber or concrete blocks

Instead of a "steep" volcano shape, a wider mound with a plateau top, gentle watering, and mulch over the whole mound works better here. That is, if you do not use a bordering wall of some sort. For a plateau top bordering wall, I began this year to cut 4" tall rings from a very large, used nursery pot made of HDPE plastic. Instead of a borderless mound, I sometimes use a very large black plastic nursery pot with the bottom 5" or so sliced off. After several years of growth, I slice off the very large pot top and begin over time to enlarge the now-potless mound into a bigger mound with plateau top. Whatever it takes to get various fruit to grow well over clay. Landscape contractors sometimes have a mountain of used plastic pots that they will sell for good prices

Don't water the mound. Water just at the bottom of the mound. Also, you should set up micro-sprinklers set at the trunk, facing outward, spraying out, away from the trunk, at the dripline (edge of canopy and somewhat beyond). Mulching can help, but you need to be careful if you're on clay soil (the reason for planting on a mound), not to retain too much soil moisture. I would be hesitant to use any black plastic on top of soil. Here in California, we have pretty intense sun, and this could cause the soil beneath the black plastic to heat up sufficiently, to kill off all your beneficial microorganisms. I would adjust how you're watering (you didn't tell us how you water, so it's a little hard to know how to advise you, exactly). No, you do not want mulch piled up against the trunk, as it can promote too much moisture and encourage root rot. Now, this is all moot if you are not on clay. There is no need to plant on a mound if you have loamy, sandy loamy or DG soils. What kind of soil do you have, and how are you watering? Also, posting a photo will help us to see what's going on.

Patty S.

Most citrus in my neighborhood have a soil-containing ring made of either old bricks, broken cement, or large rocks ( maybe 8-12 inches). We have a neighborhood with quite old houses, so someone is always replacing a chimney or driveway and it's quite easy to find free piles of bricks, stones and cement chunks, on weekend mornings. All my garden beds and tree rings are from a huge brick pile that came with my house. My family members are rather enthusiastic in their watering technique, the two-brick high retaining walls really help the soil stay put!
Pea

Hoosierquilt: I wonder what kind of plastic pots the nurseries in your area use to grow the many, many thousands of potted plants/flowers/vines/trees/bushes there? Whatever works for them should be useful to small time growers also.

I have a pile of broken bricks about 8 FT diameter by 3 FT high that I plan to use at the community garden to hold back the 40 Degree slope the fruit trees are growing in. Right now I am using a live grass wall about 60 feet long.

Steve

Thanks to all who responded.

I've been watering using a hose end nozzle (gently) or a
oscillating sprinkler (again gently). I do have a soaker
hose and that seems to be the way I need to go so I
don't have any water falling on the mound.

I do hose off the leaves to remove dirt and such. I believe
that that is beneficial to almost any plant.

My soil is what's called caliche. Terrible stuff, but then I
live in a town just outside Los Angeles in the San Gabriel
valley called Glendora. Around 100 years ago, it was one
of the centers of the citrus industry here in So Cal. Most of
what is now the Glendora residential area used to be citrus groves.

Caliche is the stuff that Adobe bricks and walls are made of. Add a binder (they used to use straw), water and caliche, mix well, let it dry in the sun and you have Adobe.

I do have an earth basin around the tree with the mound in the middle.

Not sure exactly what I will do, but I think a light layer of mulch on the mound (the rest of the growing bed is already
under mulch) and a ring of something (bricks, rocks) right
at the base of the mound will do the trick.

Do not use an oscillating sprinkler. Citrus trees do not like their trunks to get constantly wet, it will promote gummosis (foot rot, which is phytophthora). You can hose the foliage off, no problems with that, if it makes you feel better :-) During our hot, dry summers in California, it can help to reduce issues with spider mites. I have Caliche, too, in parts of my yard. The rest is DG. When I was growing up in Fullerton as a kid, we had almost all Caliche. I remember it was the first time I ever heard my dad utter a swear word :-) Which, for those of you who do not know, it is literally has hard as cement when dry, but oddly soft when soaked wet. If we want to dig a hole in dry soil, we have to use our impact shovel (translation - jack hammer. No kidding). So, if it is very heavy Caliche with a lot of clay, then planting on a mound is the way to go.

So, you need to do what I told you to do :-) Set two 180 micro sprinklers at the trunk, facing outward. Be sure you've got a bit of a basin at the bottom of your mound. Allow the micro sprinklers to run for about an hour, 1 time a week. That should do it for you. It's what most newer commercial orchards use. In your area, with the older commercial orchards, you'll see the citrus trees all planted on a raised long mound, with flood irrigation ditches on each side of that long, raised mound, flooding each side of the trees with water. Gone are those days, of course, due to our water being ridiculously expensive.

Patty S.

Patty - unfortunately, I do not have a situation where I can
set up micro sprinklers. There is no water spigot nearby.
I'd have to hook up a hose to the micro sprinklers every
time I want to water. Yes, that is a good solution, but not
one that will work for me.

When I used the oscillating sprinkler, it would only run for
5-10 minutes maximum. And with the hot, hot, hot weather
here lately, any moisture on the trunk will be dried up within
a half hour or so at the most. I won't be using the oscillating
sprinkler any more, I'm going with the soaker hose.

I do have a basin around the mound.

qaguy, I would try to set up a sprinkling system, then, if you can. I know it's a lot of work up front, but sure makes your life easier in the long run, and you will have much better success regulating your watering. And your citrus trees will do much better in the long run, as well. Otherwise, you're kind of stuck with hand watering. Watering for 5 to 10 minutes "max" is not going to provide your citrus with the proper depth of water, and basically do nothing. A soaker hose is certainly a better idea, and let it soak for long enough that your ground is moist 18 to 24 inches down. You may only need to water once or twice a week, depending on how slowly draining your soil is. Get a stick (piece of rebar, plant stake, etc.) to use to push down in your soil to see. It will be very obvious, as you simply won't be able to push the stake down if the ground is too dry :-) You can try mulching to help retain both soil and moisture. You may want to try shredded cedar mulch so it stays put, as doesn't degrade as quickly as other types of bark/wood mulch.

Patty S.