Kowhai
Sophora microphylla
Shelter is the requirement here — hard frost and wind both find the young growth first.
- Type
- Tree · Perennial
- Botanical family
- Mixed / other
- Foliage color
- Green
- Flower color
- Yellow
- Sunlight
- Full sun to light shade, in a spot the hard frosts miss.
- Watering
- Regular water while young; it handles dry spells once established.
- Feeding
- A balanced feed in spring, and nothing high in nitrogen.
- Frost tolerant
- Yes
- Flowering
- March
- Pruning
- Barely any — light shaping once the flowers are done.
- Mar–Mar Bud Break
- Mar–May Flowering
- May–Jul Fruiting
- Jul–Dec Dormancy
- Jan–Mar Dormancy
- Plant spacing
- 16 ft 5 in
- In-row spacing
- 16 ft 5 in
- Between rows
- 20 ft 6 in
- Square-foot density
- Not suited to SFG
- Root system
- Woody, with a taproot it keeps
- Working depth
- 24 in–5 ft
- Can reach
- 10 ft down where the soil allows
- Spread
- 25–41 ft across, about 1.5–2.5× the width of the plant
It anchors downwards as well as sideways, which is what lets it stand in a gale and what makes it hate being moved. Plant it small: past a few years in the ground a taprooted tree transplants badly, and often not at all.
A legume, so the roots carry nodules fixing nitrogen from the air and the tree feeds itself on poor ground.
The habit is Kowhai’s own; the figures are what that habit usually comes to at this size, not a measurement of this species. Roots follow the soil either way: a compacted pan, a high water table or heavy clay stops them well short of any of it, and deep open ground lets them go further.
- Scale insects Scale insects on the stems
- Root & crown rot Root rot in waterlogged soil
- Wind damage to young trees
Beneficial predators that hunt this plant's pests — grow their favourite flowers nearby to recruit them. companion plant
- Hoverfly SyrphidaeHunts Scale insects
Bee-mimicking flies whose legless larvae graze aphid colonies clean while the adults pollinate. A ribbon of shallow, nectar-rich flowers kept in bloom all season recruits wave after wave of them.
- Ladybird (lady beetle) CoccinellidaeHunts Scale insects
The gardener’s favorite ally: adults and their alligator-shaped larvae each eat thousands of aphids, plus scale, mealybugs, and other soft-bodied sap-suckers. Grow flat, open flowers for the adults and never spray a colony that ladybird larvae are already working.
Green-leaved trees, like this one.
The Cottage Garden Companion — the gardener's herbarium at cottagegardencompanion.com