I've been in the nursery and landscaping business in mid-Georgia since the early 1980's. This has provided much experience with planting and growing hydrangeas. In one region of the country or another and from one property to the next From one job site to the next the type of soil can vary tremendously. Almost regardless of the soil type, with proper planting techniques you can successfully plant and grow hydrangeas.

Best Growing Conditions for Hydrangea

Sun - The amount of sun a hydrangea needs or will tolerate depends on your location. In zones further north (6-4) many types of hydrangeas can and will tolerate all day exposure to direct sunlight. In zones further south (7-9) most varieties of hydrangea will appreciate a break from the sun during the hottest part of the day. When in doubt about the sun needs for a specific variety of hydrangea consult with your local nursery and garden center or whoever you purchased the plant from.

Soil Type Preferred - Hydrangeas grow best in well-drained, 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 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. They like the soil to hold a good supply of water, especially when plants are in full bud and blooms are developing, but not so much water that the soil stays constantly soggy or wet.

Soil pH Preferred - Hydrangeas will tolerate a wide range of soil pH anywhere from 5.5 to 7.5 on the scale. However, the pH of the soil can effect flower color on some types of hydrangea, particularly some varieties of the mopheads (Hydrangea macrophylla). Whenever growing plants that prefer a specific pH it's a good idea to test the soil. Testing kits are available at most local nursery and garden centers or you can buy soil test kits online here. Your local Extension Service might provide soil testing services as well. Depending on the results of the soil test, you can add lime to raise the pH or soil sulfur to lower the pH (make more acid).

Step By Step Hydrangea Planting Instructions

1. If you are uncertain about soil drainage in the planting area, it's best to test it before planting. To test soil drainage, dig a hole 12" wide by 12" deep where you intend to plant your hydrangea. 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 sandy soil, may signal potentially dry site conditions; a slower rate is a caution that you either need to improve drainage or look for a plant species that is tolerant of wet soil conditions.
2. To plant your hydrangea, begin by digging a hole 2 to 3 times as wide as the root ball or container that the plant is growing in, and about as deep as the root ball is tall. As you are digging, place the soil removed from planting hole around outside of of hole.
3. Depending on the fertility and porosity of the soil you are planting in, you might need to add a soil amendment to the native soil removed from the planting hole. When planting in heavy clay soil, it's a good idea to thoroughly mix in some good organic matter such as composted cow manure, mushroom compost, and/or sand at a 25 to 50% ratio with the clay soil. When planting in very sandy, quick-draining soil you might want to consider adding in some peat moss and or compost to help retain moisture. When planting in fertile, well-draining soil there might not be a need to add any soil amendment. If you use a soil amendment, thoroughly mix it with the native soil removed from hole before backfilling.
4. Next, remove your plant from the container it was growing in. If the plant is root- or pot-bound, you may need to use a utility knife to cut and remove the container from the root ball. Scratch the surface of the root ball to loosen the feeder roots. Do so gently so not to damage the root system.
5. Next, if the soil is well- or moderately-drained, place the plant in the planting hole with the top edge of the root ball slightly above (1-2 inches) the ground level to allow for settling. Add some soil to the bottom of the planting hole if necessary to adjust planting height. (If the soil stays soggy for more than 24 hours after a heavy rain, and there's nothing that can be done to improve drainage, I usually set the the plant so that half of the root ball or more is above the ground level, and then build a mound of soil around the entire rootball, tapering the mound from the top edge of the rootball gradually to ground level.)
6. Next, when planting so that the root ball is only slightly abve ground level, begin backfilling the planting hole by pulling soil around the root ball, tamping lightly as you go to remove any air pockets. When the hole is half-filled, soak with water and then resume backfilling. Backfill to top edge of rootball gradually tapering your soil mixture to existing ground level, as shown in the diagram above to the right. Essentially, you will be creating a slightly raised mound around the root ball. Do not place any of the backfill mixture on top of the root ball.
7. Next, use remaining soil mixture to build a water retaining berm around the outside perimeter of the planting hole. This berm will help to catch water from rainfall during the first and second growing season as your Hydrangea is becoming established. After the second season the berm can be removed.
8. Next, water deeply. I recommend a first watering with a solution of Root Stimulator (containing Vitamin B1) as this will help promote vigorous root development.
9. Next, apply a 2" layer of aged, shredded wood mulch or bark or up to 4" layer of pine straw around your newly planted shrub. Make sure not to place mulch against the trunk as this can cause disease or other damage - leave a 2" space between mulch and trunk.

Note: The above mention planting methods can be used for most types(species) of shrubs. Some types of shrubs may require slightly different planting methods. Always consult with your local nursery and garden center professional about specific planting needs for the shrubs you intend to purchase and plant.

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