How to Plant and Grow Viburnum
Where will they grow?
Viburnums are a diverse group of plants, with some growing only in very mild climates, and others thriving in extremely cold areas. The ones that we sell on butterflybushes.com are suitable for growing in USDA zones 4 or 5 through zones 8 or 9. Though there are many hundreds of wonderful, garden-worthy viburnums out there, we only offer those that serve as valuable food sources to caterpillars and/or butterflies.
Most people think of viburnums as shade plants, and they are quite adaptable to shady areas. However, in full (6+ hrs/day) to part (4-6 hrs/day) sun, you'll get the best flowering and the best leaf coverage. If you are planting viburnums to attract butterflies, sun is imperative, since they are "cold blooded" and hence more attracted to bright, warm spots.
Like most shrubs, viburnums do best in well-drained soil. Regular moisture is ideal. Once the plants are established, they can withstand dry conditions, but they look best if any kind of water stress (both too much and too little) is avoided.
Do not add anything to the soil at planting time - your natural soil is just fine. Viburnums that are grown for their berries typically require two different, compatible varieties to be planted, such as All That Glitters and All That Glows. You cannot plant two of the exact same variety and hope for fruit: in order to for berries to form, two distinct cultivars are necessary. The two varieties can be planted anywhere within 50'/15.24m of one another to ensure pollination occurs. As long as both are grown in favorable conditions, both will get fruit.
Viburnums do not have any unusual fertility requirements, so no supplemental fertilizer is required. However, if you want your plant to grow faster, you can apply a granular rose fertilizer in early spring. Subsequent applications in late spring and again in early July may be made to encourage further growth, but this is not necessary.
Viburnums that are grown for their berries cannot be trimmed or cut back at any time of the year - pruning in late winter/spring would remove the flowers (and thereby the potential for fruit), and pruning after bloom would remove the developing berries. Branches may be selectively pruned out as needed, but avoid any kind of trimming or cutting back unless you are willing to sacrifice flowers and/or fruit.
Pests and diseases
Viburnums are, by and large, resistant to deer. They are usually pretty trouble-free in terms of pests and diseases as well, though native species can incur damage from the invasive viburnum leaf beetle. Cornell University wrote this excellent article about easy, non-toxic management of that pest.