When planted right and in the right spot, Viburnum plants are exceptionally easy to grow.
Here's a breakdown of what you need to know to be growing Viburnum like the pros...
Cultural Preferences
Soil Preferences
Most Viburnum varieties tolerate a wide range of soils, however prefers a moist, but well-drained soil. That said, some Viburnum varieties might tolerate moist or dry soils better than others. Therefore, it's a good idea to know the soil moisture preferences of the specific variety of Viburnum you're planting. On every plant page in the Wilson Bros gardens website you'll find specific soil moisture preferences under the description tab.
How To Test Soil Drainage
If you are uncertain about soil drainage in the area you intend to plant your Viburnum, 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 and the need to add top soil or other organic matter to the native soil. A slower rate indicates poor draining soil and is a caution, depending on variety and specific soil moisture needs, you might need to improve drainage or look for plants that are more tolerant of wet or boggy conditions.
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.
Most Viburnum grow best in a moderately acid to slightly alkaline soil ranging between 5.5 to 8.0 on the pH scale. That said, check under the description tab on any Viburnum plant page to find the soil pH preferences for the specific Viburnum variety you are planting.
How To Test Soil pH
If you're unsure about the pH of your soil, or whether or not it's suitable for growing your Viburnum, 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 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?
Most Viburnum will grow in full sun or part shade. For best flowering provide at least 4 to 5 hours of direct sunlight or all-day lightly filtered sun. Morning sun with afternoon shade is fine. Morning shade with afternoon sun is fine. That said, check under the description tab on any Viburnum plant page to find the light preferences for the specific Viburnum variety you are planting.
How To Plant Viburnum In The Ground
Scroll for container planting instructions and care tips
Step 1
Start by digging your planting hole at least two to three times as wide and not much deeper than the root ball. 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 amend the native soil. When planting in dense clay or other compacted soils it is beneficial to thoroughly mix in some bagged top soil and/or a good planting mix at a 25 to 50 percent ratio with the soil removed from the planting hole. When planting in very sandy, quick-draining soil mix some top soil, peat moss and/or compost with the native soil to help retain moisture. When planting in a moist but well-drained soil there is no need for adding a soil amendment.
Step 3
To remove your Viburnum from the nursery container it was growing in first squeeze the sides of the pot. Then grasp the base of the plant with your fingertips and try to gently lift and remove the root ball from the container. If the root ball is stuck in the container it's best to use snips or a utility knife to cut the container away. After having removed the plant from the container, loosen some feeder roots around the surface of the root ball.
Step 4
If you are planting in well-drained soil set your plant in the planting hole so that the top edge of the root ball is at or slightly 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 soil drainage or select a different plant species more tolerant of wet soils.
Step 5
After setting your Viburnum 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. To avoid suffocating your plant, avoid placing any soil on top of the root ball.
Step 6 (Optional)
When planting Viburnum in a location that is far from a water source and in well-drained soil, you can use remaining soil mixture to build a 2 to 3-inch high 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 growing season or when the plant has established itself.
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, to stimulate early root formation and stronger root development you can also water you newly planted Viburnum with a solution of Root Stimulator, which reduces transplant shock and promotes greener, more vigorous plants.
Step 8
To conserve moisture and suppress weed growth, apply a 1 to 2" layer of shredded or chipped wood mulch or pine straw around the planting area. As the mulch decomposes it will add vital nutrients to the soil that your plant will appreciate. Avoid the use of 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 your plant as this could cause the bark to rot.
How To Plant Viburnum in a Container
Viburnum 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. When planting a Viburnum in a pot or other container, I suggest using a quality potting soil or potting mix, or a 50/50 combination thereof, in a container with a drainage hole(s). You can also add 10 to 20% pumice or Perlite to the soil mixture to help with drainage.
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 Viburnum, 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.
Container Planting Instructions
Step 1
Before filling your container with the soil mix, I suggest lining the inside bottom of the container with shade cloth or a porous landscape fabric. This will keep the drain holes from becoming stopped up with soil. If you use gravel or other materials in the bottom of the container lay the fabric over it.
Step2
To remove your Viburnum from the nursery container it was growing in first squeeze the sides of the pot. Then grasp the base of the plant with your fingertips and try to gently lift and remove the root ball from the container. If the root ball is stuck in the container it's best to use snips or a utility knife to cut the container away. After having removed the plant from the container, loosen some feeder roots around the surface of the root ball.
Step 3
Pour a small amount of your soil mixture in the bottom of the container. Set your Viburnum 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 pine bark, wood chips pr sphagnum moss to soil surface to help conserve moisture.
How To Grow & Care For Viburnum
Feeding - Watering - Pruning
Viburnums are not heavy feeders, however will benefit from fertilization.
In The Ground: To maintain good foliage color and heavy bloom, and support growth and overall health of the plant, feed your Viburnums growing in the ground after they bloom with a slow-release shrub & tree food. Alternatively, you can feed with a natural organic plant food. To avoid stimulating new growth that could be damaged by an early frost, cease fertilization two months prior to the first frost date in your area.
In Pots: Feed Viburnum growing in pots or other containers with a slow-release granular fertilizer or water soluble liquid plant food listed for use in containers.
How much fertilizer?
This will depend of course on the size of the Viburnum you are fertilizing and the type of fertilizer. Regarding slow-release shrub and tree fertilizers, you'll find application instructions on the package label.
Where to spread the fertilizer?
The root system of a Viburnum might grow 18 inches deep or more but the majority of the feeder roots responsible for absorbing nutrients are in the top 12 inches of soil. Spreading fertilizer on the soil surface is sufficient to reach these feeder roots.
Spread fertilizer evenly around each shrub, beginning a foot or so from its trunk, and then one foot beyond the drip line (branch perimeter) for every 5 feet in plant height.
Note: If the soil is compacted or subject to excessive water runoff, the fertilizer can be applied in a series of holes 6 to 8 inches deep in the same area with about five holes per 1 inch of trunk diameter.
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.
Most Viburnum grow best in a moderately acid to slightly alkaline soil ranging between 5.5 to 8.0 on the pH scale. That said, check under the description tab on any Viburnum plant page to find the soil pH preferences for the specific Viburnum variety you are planting.
Learn More: What Is Soil pH And How To Adjust It?
How To Water Viburnum
Most Viburnum prefer a moist, well-drained soil. Most varieties do not like constantly soggy or wet soil conditions, which can lead to root rot and other harmful plant diseases. That said, some Viburnum varieties might require more water while others are drought tolerant. Therefore, it's best to know the soil moisture needs of the specific Viburnum variety you are growing. On every Viburnum plant page in Wilson Bros Gardens website you'll find specific soil moisture needs under the Description tab.
Note: When watering with an automated irrigation system it's best to set your timer to water during the early morning hours and not in the late evening or at night, which can lead to the onset of fungus and other foliar diseases. Test the soil moisture often during the first few weeks after planting and adjust irrigation time if necessary to maintain a moist but not wet soil.
At Planting Time
Immediately after planting deep soak the soil in 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 Viburnum 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.
During the First Active Growth Season
In average garden soil you should not have to water your newly planted Viburnum every day. More often than not, this causes soggy soil conditions that can lead to root rot and other harmful plant diseases. In the absence of sufficient rainfall, water only as needed to keep the root ball and surrounding soil damp to moist. Keep in mind that deep soaking less frequently, and allowing the soil to dry out somewhat before watering again, is much better than splashing just a little water on the plants every day. Shrubs planted during the winter dormant season, when plants are not actively growing and evaporation is much slower, will require much less water. So, be extra careful not to overwater during winter!
Thereafter
When established, Chinese Snowball Viburnum are quite drought tolerant. Only during prolonged drought will established plants require supplemental irrigation. If you see new leaves wilting or the tips of new stems bending over during dry weather this could be a sign your plants could use a good deep soaking. Just make sure to check soil moisture before watering.
How To Prune Viburnum Plants
Viburnums do not require pruning, however plants can be pruned for shaping, to control size, or to remove damaged or dead branches. Taller growing Viburnum varieties can be pruned to form very attractive small trees.
When to Prune
More extensive pruning to reduce size, shape the plant overall, or to tree form should be performed in late winter or early spring, before new growth begins to emerge. Light pruning to cut back a stray, damaged or dead branch can be performed almost any time of year. Damaged or dead branches should be removed as they occur.
Note: To avoid frost damage to new growth that is stimulated by pruning, cease pruning Viburnum two months prior to the average first frost date in your area.
How to Prune
Use a sharp pair of bypass hand pruners when pruning Viburnum. When pruning branches larger than 1" it may be necessary to use long-handle lopper pruners.
How you prune a Viburnum will depend on the variety:
Snowball Viburnum (V. macrocephalum)
This shrub or small tree flowers on old wood, so do not prune until after it flowers. Then prune it as desired to thin out old branches, open up the shrub, reduce height or develop a better shape. To remove a branch or stem, make cuts a quarter inch from the point where they intersect another branch or trunk. Avoid cutting too close to the point of origin, which can remove some of the bark and cause injury. Remove dead or diseased wood by pruning the entire branch back to a point of healthy, disease-free growth. You can rejuvenate old plants by cutting them down to a short stump but, after doing so, the plant may not bloom for two years.
Other Viburnums
Healthy specimens rarely need pruning. Prune Viburnums after flowering only if pruning is necessary for shaping. Old or crowded plants may be thinned and shortened to bring flowers to eye level. After 4 to 5 years you may remove 1/3 of the oldest stems, and thereafter prune every 2 or 3 years.
How To Tree Form A Viburnum
Taller growing Viburnum can be pruned to form very attractive single- or multi-trunk small trees.
Young Plants
If you have a young multi-stem Viburnum under 2 feet in height, choose 1 to 3 of the healthiest and most upright trunks or main branches and remove the rest by cutting them off 1/4" above the ground or from their origin on a trunk. That said, more than 3 trunks is okay. Then allow your Viburnum to grow to 4 feet tall or more before removing lower branches.
Older Plants
If your Viburnum is 4 feet or taller, begin tree-forming by selecting 1 to 3 of the healthiest and most upright trunks or main branches. If you're lucky, there will be only 1 to 3. More than 3 trunks is okay. Remove unwanted trunks or main branches by cutting them off 1/4" above the ground or from their origin on a trunk. Make sure before you remove a trunk or branch that it will not ruin the look of the canopy (top of the tree). Then start removing the lowest branches and side shoots on the trunks moving your way up and leaving lateral branches on the top 2 feet of growth on a 4- to 5-foot tall shrub.
In future years, as your tree grows taller, you can clip off lower branches, side shoots, or suckers until your tree has the desired size and proportion of canopy to trunk. Removal of larger branches should be done during late winter, before new growth has emerged.
Plant Long & Prosper!