Posted by Brent Wilson on 8/25/2016 to
Fruit Gardening
Plum trees are exceptionally easy to grow and will provide loads of tasty fruits when planted right and in the right spot.
Here's a breakdown of what you need to know...
Soil
Plum trees grow and produce the best fruit in well-drained but moist fertile soil that is rich in organic matter, but tolerate a wide range of soils as long as water and nutrients are not limiting and soil pH is adequate. They like the soil to hold a good supply of water, especially when the fruits are developing in summer, but not so much water that the soil stays constantly soggy or wet, which can cause problems with the roots. They are tolerant of heavy clay soils if drainage is good. In soil with low fertility or compact clay it'll be worth your time to mix in some organic compost to the native soil.
How To Test Soil Drainage: If you are uncertain about soil drainage in the area you intend to plant, it's well worth taking the time to test the drainage before planting. To test soil drainage, dig a hole 12" wide by 12" deep in the planting area. Fill the hole with water and let it drain. Then, after it drains, fill it with water again, but this time clock how long it takes to drain. In well-drained soil the water level will go down at a rate of about 1 inch an hour. A faster rate, such as in loose, sandy soil, may signal potentially dry site conditions. A slower rate indicates poor draining soil and could be a caution you might need to improve drainage, plant in a raised mound or bed, or look for plants that are more tolerant of wet or boggy conditions.
Soil pH
Plum trees grow best in a slightly acid to neutral soil ranging between 6.0 and 6.5 on the pH scale. Most average garden soils fall between a pH range of 6.0 to 7.0.
Testing Soil pH Soil pH is a measurement of the alkalinity or acidity of soil and is measured on a scale of 1-14, with 7 as the neutral mark. Any measurement below 7 indicates acid soil conditions, and anything above 7 indicates alkaline. If you're unsure about the pH of your soil, or whether or not it is suitable for growing plum trees, it's a good idea to test the pH in the planting area. You can quickly test soil pH with an inexpensive soil pH tester probe. To raise the pH (make more alkaline) you can add pelletized limestone to the soil. To lower the pH (make more acid) you can apply Soil Sulfur, Aluminum Sulfate, or Chelated Iron. Adding organic compost to the soil or using compost as mulch can also help to increase acidity and maintain acid soil conditions.
Learn More: What is Soil pH and How To Adjust It?
Light Needs
The best and most fruits will be produced when plum trees are growing in full sun. However, trees that receive a little shade during the hottest part of summer days will still produce good crops of fruit.
Step-By-Step Planting Instructions
Step 1
Start by digging your planting hole at least three times as wide and as deep or not much deeper than the root ball of your plant. The wider the hole the better. Place native soil removed from planting hole around the perimeter of the hole, in a wheel barrow, or on a tarp.
Step 2
Depending on the type, fertility and porosity of the soil in the planting area, it may be beneficial to amend the native soil. When planting in heavy clay soil mix in a good soil conditioner, compost, and/or planting mix at a 50/50 ratio with the soil to enhance porosity and ensure good drainage. When planting in a sandy, quick-draining soil amending with top soil, organic compost, and/or peat moss will help to retain moisture and supply vital plant nutrients. When planting in fertile, loamy, well-drained moist soil there may not be a need to amend soil.
Step 3
To remove your tree from the container it was growing in, firmly grasp the base of the trunk and try to very gently lift and remove it from its container. If the root ball is stuck in the container either cut the container away or place the plant on it's side and gently pound on the side of the container to loosen the root ball. After having removed the plant from the container, loosen some feeder roots around the surface of the root ball. If root bound, you can gently spray the sides and bottom of the root ball with a stream of water from a garden hose. This will help to wash away some soil from the exterior of the root ball making it easier to loosen roots.
Step 4
Set your tree in the planting hole so that the top edge of the rootball is at or slightly above ground level to allow for settling. It may be necessary to place some of your backfill soil mixture in the bottom of the hole to achieve proper planting height. If your planting site drains slowly after rainfall, plant with the root ball several inches or more above the ground level. If your soil stays constantly soggy or wet take measures to improve drainage in the planting site.
NOTE: All plum trees purchased from a nursery are grafted. This means that a branch was removed from a specific variety of tree and then "attached" (grafted) to a seedling of another type of tree. Take care when you plant a new plum tree not to bury the graft, where the fruiting stock joins the rootstock. This is usually a bulging area near the base of the trunk of the tree.
Step 5
After setting your tree in the planting hole, use one hand to hold the tree straight while using your other hand to begin backfilling the soil mixture around the root ball, tamping as you go to remove air pockets. When you have filled the hole to the halfway point you can soak the soil. Then continue backfilling to the top edge of the root ball. If you are planting the root ball higher than ground level taper your soil mixture gradually from the top edge of the root ball to the ground level. To avoid suffocating your plant, do not put any soil on top of the root ball.
Step 6 (Optional)
When planting your tree in a site far away from a water source you can use remaining soil mixture to build a water retaining berm (catch basin) around the outside perimeter of the planting hole. This basin will help to collect water from rainfall and irrigation often reducing the need for hand-watering. The berm can be removed after a growing season or two.
Step 7
Next, deeply water the planting area, including the root ball, to a depth equal to the height of the root ball. For an extra boost, you can water your newly planted tree with a solution of Root Stimulator, which stimulates early root formation and stronger root development. Root Stimulator reduces plant shock and promotes greener, more vigorous plants.
Step 8
Apply a 1 to 2" layer of pine bark mulch or a good organic compost, or a 3- 4" layer of pine straw, around your newly planted tree. Do not use freshly chipped or shredded wood for mulch until it has cured in a pile for at least 6 months, a year is better. Avoid placing or piling mulch directly against the base of the plant as this could cause problems with the bark.
Apply a 1 to 2" layer of pine bark mulch or a good organic compost, or a 3- 4" layer of pine straw, around your newly planted tree. Do not use freshly chipped or shredded wood for mulch until it has cured in a pile for at least 6 months, a year is better. Avoid placing or piling mulch directly against the base of the plant as this could cause problems with the bark.
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