Hydrangeas are one of American gardeners favorite summer flowering plants, for good reason. They produce loads of colorful flowers! They are exceptionally easy to grow and will perform their best when planted right and in the right spot. 

Here's a breakdown of what you need to know regarding planting hydrangeas...


Cultural Preferences


Important: Before choosing a variety of Hydrangea to plant in your landscape or gardens, make sure to verify whether or not the variety will grow in your USDA Plant Hardiness Zone. You'll find USDA Zone listed on every Hydrangea page in Wilson Bros Gardens.


Soil 

In Ground: Hydrangea are easy to grow in average, moist but well-drained soil. As with so many other ornamental shrubs, constantly soggy or wet soil can cause root rot and other harmful plant diseases. It's a good idea to test soil drainage in the planting area before planting.

In Pots & Containers: Hydrangea growing in pots appreciate a moist but well-drained soil. Constantly soggy soil can and often will cause root rot or other harmful or deadly plant diseases. Therefore, when planting a Hydrangea in a container or pot, I recommend using a quality potting soil or potting mix, or a 50/50 combination thereof in a container that has a drainage hole(s). You can also add 10 to 20 percent perlite or pumice to the soil mix to enhance drainage. 


How To Test Soil Drainage  

If you are uncertain about soil drainage in the area you intend to plant your Hydrangea, 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. 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 and possibly a need to add organic matter to help retain moisture. A slower rate indicates poor draining soil and is a caution you 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

Hydrangeas grow best in a soil that ranges between 5.0 and 8.0 on the pH scale. Soil pH can effect bloom color on some hydrangeas, specifically mopheads/French hydrangeas and lacecap hydrangeas. Soil pH can effect bloom color. An acid soil will produce one color while an alkaline soil produces a different color. For example, you can turn some varieties of pink Hydrangea to blue by lowering the pH (making it more acid). The flowers of white Hydrangea do not change color regardless of soil pH. 

In strongly acid soil (pH below 6) hydrangea flowers turn blue. In alkaline soil (pH above 7) flowers turn pink or even red. In slightly acid or neutral soil (pH 6 to 7), blooms may be purple or a mix of blue and pink on a the same shrub. Keep in mind that some Hydrangea varieties vary in their sensitivity to pH. 


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, and whether or not it's suitable for growing Hydrangea, it's a good idea to test the soil 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 SulfurAluminum 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.



Light Needs

Hydrangea will tolerate full sun in northern zones but likes some afternoon shade or filtered sun in warmer southern zones. I recommend at least 5 hours of direct sunlight per day or all day lightly filtered sun for best flowering. Note that oakleaf (H. quercifolia) and peegee (H. paniculata) hydrangea varieties will generally tolerate more sun than the mopheads (H. macrophylla) and other Hydrangea species.



Planting Hydrangeas in The Ground

Scroll down for container planting instructions


Step 1

Start by digging your planting hole at least two to three times as wide and no deeper than the rootball of your hydrangea. 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 you might need to mix in a soil amendment to the native soil removed from the planting hole. When planting in dense clay or poor soil it is beneficial to thoroughly mix in some good organic matter, such as composted cow manure, mushroom compost, sand, and/or a good planting mix at a 50/50 ratio with the clay soil. When planting in very sandy, quick-draining soil you might want to consider mixing in some top soil, peat moss and/or compost to help retain moisture. When planting in fertile, loamy, well-drained moist soil there is no need for adding a soil amendment.


Step 3

To remove your Hydrangea from the container it was growing in try to lift and remove the rootball from its container. If the root ball is stuck in the container it's best to cut the container away. After having removed the plant from the container, use your finger or a claw tool to loosen some feeder roots around the surface of the root ball. If root bound, you can 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 surface of the root ball making it easier to loosen roots.


Step 4

If you are planting in well-drained soil set your Hydrangea in the planting hole so that the top edge of the rootball is at or slightly above ground level (1-inch or so) to allow for settling. If your soil is moderately drained, meaning it drains slowly after rain, the top of the root ball should be 2 to 3 inches above ground level. If necessary, add some backfill soil mixture to the bottom of the hole to achieve proper planting height. 

Note:  If the soil is poorly drained (constantly soggy or wet) improve drainage, plant the root ball in a raised bed entirely above ground level, or select a different plant species more tolerant of wet soils.



Step 5

After setting your Hydrangea in the planting hole, use one hand to hold the plant straight and your other hand to begin back-filling your 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 back-filling 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, avoid placing any soil on top of the root ball.


Step 6 (Optional)

When planting your Hydrangea in a site site far away from a water source you can use remaining soil mixture to build a water retaining berm (catch basin/doughnut) 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 year or so.


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 Hydrangea 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 cured, shredded or chipped wood mulch or pine straw around the planting area to conserve moisture and to suppress weed growth. Avoid the use of fresh 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 your plant as this could cause the bark to rot.


Container Planting Instructions


Hydrangea growing in pots appreciate a moist but well-drained soil. Constantly soggy soil can and often will cause root rot or other harmful or deadly plant diseases. Therefore, when planting a Hydrangea in a container or pot, I recommend using a quality potting soil or potting mix, or a 50/50 combination thereof in a container that has a drainage hole(s). You can also add 10 to 20 percent perlite or pumice to the soil mix to enhance drainage. 

Also make sure to choose a container that is large enough to allow for 2 to 3 years of growth before shifting up to a larger size container. This might mean your planting pot would be 8 inches or more in width than the root ball of your plant. 

Container color will matter as well. Not only will you want to pick a color of container that goes well with the flower and foliage color of your Hydrangea, you'll also want to pick a container that matches the style of your home or other structures and other plants in the surrounding environment. 

Many nursery & garden centers offer a wide variety of containers to choose from. Before heading out to buy a container take pictures of your home and the surrounding environment. Doing so will help you to choose just the right color and style.


Step 1

Before filling your container with the soil mix, we recommend lining the bottom with shade cloth or a porous landscape fabric. This will keep the drain holes from becoming stopped up with soil. 


Step 2

To remove your Hydrangea from the container it was growing in try to lift and remove the rootball from its container. If the root ball is stuck in the container it's best to cut the container away. After having removed the plant from the container, use your finger or a claw tool to loosen some feeder roots around the surface of the root ball. If root bound, you can 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 surface of the root ball making it easier to loosen roots.


Step 3

Pour a small amount of your soil mixture in the bottom of the container. Set the plant in the container and make necessary adjustments by adding or removing some soil so that the top edge of the root ball will sit 1/2 to 1" below the rim of the container.



Step 4

Backfill with your potting soil around root ball, tamping as you go, until the level of potting soil is even with the top edge of root ball.


Step 5

Water thoroughly until water starts to drain from the holes in the bottom of the container. Add more potting mix if settling occurs during watering.


Step 6 (Optional)

Apply a 1/2" layer of wood chips or sphagnum moss to soil surface to help conserve moisture.



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