Silk Tree
Albizia julibrissin
Warmth and shelter come before every other consideration — a cold, open site is where this one fails.
- Type
- Tree · Perennial
- Botanical family
- Mixed / other
- Foliage color
- Green · Gold and chartreuse
- Flower color
- Pink
- Sunlight
- Full sun and genuine warmth, in a site with shelter.
- Watering
- Regular water for the first 2–3 years; drought stops mattering after that.
- Feeding
- A light balanced feed in spring, and nothing high in nitrogen.
- Frost tolerant
- Yes
- Flowering
- June
- Pruning
- Late winter and no other time, while it is fully dormant.
- Apr–Jun Bud Break
- Jun–Aug Flowering
- Aug–Nov Fruiting
- Nov–Dec Dormancy
- Jan–Apr Dormancy
- Plant spacing
- 26 ft 3 in
- In-row spacing
- 26 ft 3 in
- Between rows
- 32 ft 10 in
- Square-foot density
- Not suited to SFG
- Root system
- Woody, shallow and far-reaching
- Working depth
- 12–24 in
- Can reach
- 4 ft down where the soil allows
- Spread
- 52–79 ft across, about 2–3× the width of the plant
Almost all of a tree’s roots are in the top two feet of soil, where the air is, and they run out well past the branch tips. The deep taproot most people picture belongs to the seedling; the tree grows out of it and spends the rest of its life spreading sideways instead.
A legume that fixes its own nitrogen, suckers from the roots and seeds itself freely, which together are why it is invasive across the southeastern United States.
The habit is Silk Tree’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.
Beneficial predators that hunt this plant's pests — grow their favourite flowers nearby to recruit them. companion plant
- Bats ChiropteraHunts Fall webworm
A single bat takes hundreds of moths and mosquitoes in a night, and the moths are the parents of your cutworms, corn earworms and hornworms. Put up a bat box on a warm south wall, leave a night-scented corner unlit, and never spray after dark.
- 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.
- Tachinid fly TachinidaeHunts Fall webworm
Bristly, house-fly-lookalike parasitoids that lay eggs on caterpillars, beetle grubs, and earwigs — the maggot consumes the host from within. Adults sip nectar from shallow umbels and daisies.
Trees, like this one.
The Cottage Garden Companion — the gardener's herbarium at cottagegardencompanion.com