Planting a Japanese Snowball: Space, Soil and Site

The spacing mistake that cannot be undone

A young Japanese snowball in a container looks like an upright shrub with a few side branches. It is not. As it matures the branching becomes strongly horizontal, and the spread usually finishes greater than the height: a plant that reaches eight to twelve feet (2.4 to 3.6 m) tall will commonly cover twelve to fifteen feet (3.6 to 4.5 m) across.

That matters more here than for most shrubs, because the usual remedy for a plant that has outgrown its space is to cut it narrower, and that remedy is not available. Shortening the tiers removes the flowering wood and the layered structure at the same time. A snowball planted three feet from a path becomes a permanent annual pruning problem, and after a few years of that it is neither a good shrub nor a good path.

So set it out for the mature spread. If the space is genuinely only six or eight feet wide, this is the wrong plant for that space, and it is much cheaper to accept that at planting time than four years later.

Site and spacing

Full sun gives the heaviest flowering, but in hot summer regions the plant is better with sun until early afternoon and shade after it, which keeps the leaves from scorching and the soil from drying. Deep shade produces a thin, stretched plant with sparse tiers. Shelter from the strongest wind helps, because the long horizontal extensions are brittle and snap at the fork.

The soil wants to be moist and free draining, with organic matter worked through it, and slightly acidic to neutral suits it best. It does not tolerate standing water at the roots, and it does not tolerate a thin dry soil over rubble. Both problems show up the same way, as scorched leaf margins in midsummer, so check drainage before blaming the heat.

Getting it in the ground

Autumn is the best season in most climates, while the soil still holds summer warmth and the plant is shutting down for the year, which gives the roots months to establish before the first dry spell. Early spring is the second choice. Avoid planting in the middle of summer, and avoid planting into frozen or waterlogged ground.

1. Water the plant in its pot first Soak the rootball thoroughly an hour before you start. A dry rootball planted into moist soil will stay dry for weeks, because water runs around it rather than into it.
2. Dig wide rather than deep Open a hole two to three times the width of the rootball but no deeper than the rootball itself. Loosen the sides so roots can leave the hole, and break up any compacted layer at the bottom.
3. Check the flare before you backfill Lay a straight edge across the hole. The point where the trunk widens into the roots should sit level with the surrounding soil, or an inch (2 to 3 cm) proud on heavy ground.
4. Tease out circling roots Pull the outer roots loose with your fingers, and cut through any that circle the rootball. Roots left circling stay circling, and the plant never anchors properly.
5. Orient the tiers before you fill Turn the plant so its best developed side faces the main viewing point and the lowest tier has open ground to run into. This is the moment to make that decision, not later.
6. Backfill and settle with water, not with feet Return the original soil in stages, watering each stage to collapse air pockets. Firm gently by hand. Treading the soil hard destroys the structure you just loosened.
7. Mulch, keeping the trunk clear Spread two to three inches (5 to 8 cm) of bark or compost over the root area, out to the drip line, with a hand's width of clear ground around the stem base.

Do not add fertilizer to the planting hole. Fresh roots meeting concentrated feed are checked rather than encouraged, and a plant set in good soil with a mulch on top has everything it needs for its first year.

Whether you will get berries

Before planting, decide which form you are dealing with, because it settles the fruit question permanently. Plants carrying fully double, ball shaped white flower heads are sterile: the showy globe is made entirely of enlarged, infertile florets, there are no functional flowers inside it, and no amount of pollination or companion planting will produce a single berry. The flat lacecap type, with a ring of large white bracts around a center of small fertile flowers, does set fruit, and carries red berries that darken to black by late summer.

So if berries and birds are part of the reason you want this shrub, choose the flat flowered form and plant it in a position where you can see the fruit. If you want the pure white globes, plant them knowing the season ends when the flowers do. Planting a second snowball nearby does not help a sterile form, and it is a common and expensive misunderstanding.

One thing does apply to both forms. Set the plant where the horizontal tiers are seen from the side and slightly below rather than looked down on from above, because the layered flowering only reads properly in profile.

The first year

For the first full growing season, treat the plant as if it were still in its pot. The rootball holds most of its roots, it dries out much faster than the ground around it, and it is the only thing you are actually watering. Soak it directly, weekly in normal weather and twice a week in heat, until the leaves drop in autumn.

Do not prune in the first year beyond removing anything broken in transit. Do not feed. Do let the lowest tier reach the ground if it wants to, and note in your records the planting date, the measured width of the plant at planting and the direction you faced it. Measuring the spread again each autumn is the clearest sign of whether the plant is establishing, and it also tells you well in advance when it is going to reach the path.