This is one method we use in high drainage sand and a dry season in Florida, to avoid having to water regularly or irrigate. When timed with rainy seasons, we are able to get trees established with no irrigation needed except in months where there is drought or no rain.
This method can allow you to plant a tree and walk away without watering it, for a month or more depending on various weather factors. This method can be especially useful for hedges and other tree plantings in areas that have difficult water access, and in drylands areas where there is no rainfall for many days or weeks. It can be helpful in many different climates and soil types. It isn’t usually needed and might cause problems in heavy, wet clay soils or areas with high water tables or that flood.
- Dig a hole 2-4 times as wide as the pot and a little deeper than the pot size. If soil is compacted, dig deeper and wider, to loosen the soil. We want to encourage the roots to go both out and down.
- Fill the hole to the top with water and let it soak in. Then repeat. You are saturating the entire area so that it will hold whatever rainwater falls better. This could take days in heavy clay soil. If you get adequate rainfall or soil is easily saturated, this step is not necessary. This step is very helpful in the sandy soils of Florida.
- Filling up the hole with water. Note that this whole is about 2X the size of the pot. This encourages roots to spread out. Note the logs around the donut, and that sand from the hole is mounded on the downslope. Think through the design of your water catchment before digging, to save yourself shovel time.
- Once the water has soaked in, fill the bottom of the hole with soil until the top of the soil in the pot is about even with the top of the ground surrounding the hole. Place a small shovelful of a mixture of aged manure and compost/soil in the bottom of hole. We want to keep the stem above the soil, because organic matter right up against the stem can cause disease in some fruit trees.
- You can also place some small sticks or stems or a couple of handfuls of wood chips in the hole, especially of oak. This encourages beneficial fungi, builds organic matter, and can help hold water. We get this wood from our own oak trees that shed it yearly, but have gotten it from neighbors when we didn't have an oak.
- Filling the hole the second time. Meanwhile, a layer of manure, then wood chips and some logs (on the outside) have been laid. Note they are laid in a semi circle on the downslope. We’re planting drought tolerant trees here that may never be watered again except in severe drought situations, so we want to give them as much opportunity to capture any runoff as we can.
- Remove the tree from its pot. Generally it’s better to avoid grabbing the stem and pulling but rather loosening the root ball in the pot, then turning it upside down and shaking it out over the hole. You can damage and tear roots by pulling the tree out by the stem.
- Ensure the roots are spread out and if there is a tap root it is not twisted around but as straight down as possible (even if you have to dig a space for it). Break up the roots if they are “pot-bound” (meaning that they circle around the outside edges of the pot, bound up). Even if you break roots off, the tree will grow better if the roots are pointed outward and downward cleanly. When pot bound, roots can sometimes stay that way for years in the ground, and the tree will stay stunted as if it’s still in the pot.
- Place the tree in hole - ensure that where the stem and root meet is at least one inch above ground level. You do not want to cover the stem with soil or leaves or anything else or have it in an indentation where organic matter or dirt will gather. The place where the stem meets the root is a vulnerable place in many trees, where disease can take hold. This is especially true of stone fruit trees and a few others. Keep the stem clean. A big mistake people make with tree planting is covering the stem instead of just the root zone. This can kill a stone fruit tree.
- Fill hole with a mixture of ½ native soil (that you dug out of the hole), ½ compost or manure - or ⅔ native soil ⅓ manure. You can add more tree stems or wood chips here as well. The newly planted tree stem will have a little hill leading up to it, with a little valley extending 2-3 feet out from the tree and encircling it. Fill the hole with water when ½ filled with dirt (to get the air holes out of it). Then finish filling the hole with dirt, and water deeply. If you fill the hole with pure compost, you are encouraging the plant to keep its roots within that hole instead of reaching out and really establishing itself. We continue to encourage the plant to reach out more and more. Note, you can fill the hole with just the parent material if you have good soil. We add compost to reduce the shock of going from good potting soil to pure sand. We will continue to add organic material around the tree to encourage the roots to continue outward.
- Create a donut mound of sheet mulch, starting at 2-3 feet from the tree stem (mound will include aged manure, seaweed, grass clippings, coffee grounds, even kitchen waste, with wood chips going on top). This mound will be about a foot high. Apply the fertility ring first, cardboard if you want to suppress weeds, and wood chips on top of cardboard on the outside (to keep weeds down). Saturate the donut and tree with water. Unless you have a multi day hot, windy drought in summer or 2 week or more drought in winter, you should not have to water the tree.
- If you want to add more water catchment potential to the tree, create a half circle or half moon or “fish scale” as we call it rather than a full donut, on the downslope away from the tree. Leave the upslope open so that water can flow into the root zone, but the fertility berm will hold it there and allow it to soak in.
- You can add nurse logs around the edges of the donut as well. This encourages beneficial fungi and other beneficial elements and they help hold moisture.
Note: If you have heavy clay soils and regular rain, you may not want water to stand there and might leave the donut open on the downslope so water can drain out.
- Observe, and think about what water does in that area and what your tree needs, and design for it!
Note: Citrus is a surface feeder so it doesn't like cardboard. Recommend that you clear the lawn around the tree completely, put a ring of cardboard around the edge or skip entirely, and mulch 3” with a mix of manure or seaweed, and wood chips.
- The donut feeds the tree roots as water or rain send nutrition into the sand. This mulch donut should last 8 months to one year depending on how much material you have access to and are able to bring in. This is a lot better than quarterly or monthly fertilizing that is usually recommended!
- Add another donut once per year, extending the donut outward depending on how much the tree has grown. We call for a “manure shoveling party” to add manure once per year in the spring, which all our friends look forward to!
- Another option is to simply add “chop and drop” to the donut area and extend that outward. This is the ultimate goal of our tree planting; we want to get all the food the tree needs from our site itself. We do that via nitrogen fixing trees and other plants, to help them do well in our ecosystem.