Gadenin日本語Get the appUnderstand the root ball before you dig
Slide a satsuki out of its pot and you will see a dense felt of hair-fine roots, often wound tightly around the outside of the ball and matted at the base. There are no thick anchoring roots. This mat is efficient at taking up water from a small volume, but it will not push out into surrounding soil on its own if it has set hard, and a plant left in that state sits in its original ball and dries out repeatedly while the soil around it stays wet.
Tease the outside of the ball before planting. Work your fingers into the sides and base, pull the outer roots loose and, where the mat has gone hard and corky, score down the sides with a knife in three or four places. This looks brutal and is not. The severed root ends branch and the new tips grow out into the new soil, which is exactly what you need in the first season.
Soak the ball fully before it goes in the ground. A dry peat-based root ball repels water once it is buried and will stay dry under a soaked soil surface for weeks. Stand the plant in a bucket until the bubbles stop, which usually takes ten to twenty minutes, and plant it wet.
If the root ball is bone dry and hard when you buy the plant, deal with that before anything else. A satsuki that has been allowed to dry out completely in its pot may have lost fine roots already, and it needs a season of recovery in shade rather than immediate planting into an exposed spot.
Plant high, never deep
The commonest way to kill a satsuki is to plant it at the depth you would use for an ordinary shrub. The fine root mat needs air. Bury the top of the ball under two inches (5 cm) of soil and the roots suffocate slowly, the plant sulks for a season and then declines with no obvious cause. Every guide repeats this because every year people do it anyway.
Set the plant so the top of the root ball sits an inch (2.5 cm) proud of the surrounding soil, then bring the soil up to meet it and taper it away. On heavy ground go further and plant into a raised mound or a low raised bed. It feels wrong to leave a root ball standing above the level, and it is the difference between a plant that grows away and one that never establishes.
Dig the hole wide rather than deep. Three times the width of the root ball and no deeper than its height gives the fine roots a generous band of loosened, improved soil to run into, while the base of the ball rests on undisturbed ground so the plant cannot sink later as backfill settles.
- Improve a wide area, not just the hole Fork composted bark or leaf mold through the top eight inches (20 cm) of soil across an area at least three feet (90 cm) across. Improving only the planting hole creates a sump that fills with water.
- Check the depth with a cane Lay a cane across the hole and sit the plant in. The top of the root ball should stand an inch (2.5 cm) above the cane before you backfill anything.
- Backfill in stages and firm gently Add soil in layers, working it into the gaps with your fingers rather than treading it. Firm pressure crushes the fine roots and squeezes out the air they need.
- Water in thoroughly Give the plant several gallons slowly, so water reaches the base of the ball rather than running off the proud surface. Let it soak in, then top up any soil that settles.
- Mulch, keeping the stem clear Spread two inches (5 cm) of composted bark or pine needles over the root zone and out beyond it, leaving a bare inch (2.5 cm) around the stem so the bark stays dry.
Containers, which is how most satsuki are grown
Satsuki take to container culture better than almost any other flowering shrub, which is why they are the classic subject for training in pots. In a container you control the medium and the water, and you can move the plant into shelter for its flowering weeks so the display is not shredded by a summer storm. For most growers a pot is the better option, not a compromise.
The medium should be open and acid, based on coarse acidic grit or pumice in the range of an eighth to a quarter inch (3 to 6 mm), with acidic organic matter blended through it. Water must run out of the base within a few seconds of going in, and the particles must stay damp between waterings. A dense general-purpose compost holds too much water around the fine roots and collapses to sludge within two seasons.
Pot into a container only slightly larger than the root ball, since a satsuki in an oversized pot sits in a mass of wet unused medium. Shallow pots suit the shallow root system better than deep ones. Set the surface of the root ball level with or fractionally above the rim of the medium, and leave a half inch (1 cm) of space below the pot rim so you can flood the surface when watering.
| Site factor | What a satsuki wants | What goes wrong otherwise |
|---|---|---|
| Light | Bright morning sun, shade from midday on | Scorched leaves, bleached flowers, dry roots |
| Soil reaction | Acid, pH 4.5 to 5.5 | Yellow leaves with green veins, slow starvation |
| Drainage | Free, with moisture held in the particles | Root rot in wet ground, drought stress in dry |
| Planting depth | Root ball an inch (2.5 cm) proud | Suffocated roots and a slow unexplained decline |
| Shelter | Out of drying wind and driving rain in flower | Wind burn on foliage, flowers destroyed in a day |
| Competition | Clear of tree roots and dense planting | Loses the water it needs at the surface |
The first season after planting
A newly planted satsuki has not yet grown roots beyond its original ball, so for the whole first season you are watering the ball, not the bed. Direct water onto the root ball itself, slowly and deeply, twice a week in warm weather and more in a dry spell. A bed that looks damp on the surface tells you nothing about whether that proud root ball has water in it.
Do not feed at planting. New roots grow into unfertilised soil more readily, and fertilizer salts around damaged fine roots do harm. Wait until the plant has flowered and finished, then begin a half-strength acid-plant feed through the rest of the summer, stopping in good time so late growth ripens before cold weather.
If the plant is set out while it is carrying flower buds, consider removing them. A satsuki flowering in its first weeks in the ground spends energy on the display that it needs for roots, and the flowers will be poor anyway. Taking the buds off costs you one season and buys you a stronger plant for every season after.
Write down the planting date and the exact position, including which way the plant faces and where the afternoon shade falls. If the plant scorches or fails to set buds, the site record is the first evidence you will want, and by the following summer nobody remembers the detail accurately.