Silver wattle

Silver wattle: how do you recognise it?

Habit

Fast-growing tree with a light, open crown. Outdoors in a warm spot up to about 8 m; in a pot usually 2–3 m.

Leaves

Twice pinnate, with a great many tiny leaflets; silver-grey to blue-green, soft and fern-like. Evergreen.

Flowers

Fluffy golden-yellow balls about half a centimetre across, in long sprays, in February–March.

Scent

Sweet and honey-like, especially on sunny days.

Roots

Fairly shallow: it is easily blown over or knocked askew, so a sturdy stake is needed. It also produces suckers.

Flowering: February–March · Plants: May–June · Pruning: April

Why grow it?

• Flowers in the middle of winter, in February–March, when little else is in bloom.
• A lovely sweet scent, indoors in a vase as well.
• Evergreen, fine silver-grey foliage that looks good all year.
• Early pollen for bees on mild days at the end of winter.
• Grows fast: in a pot you have a sizeable flowering shrub within a few years.
• A touch of the south of France on a sheltered patio or in a cold greenhouse.

Silver wattle: where does it grow best?

• Full sun and warmth; outdoors only against a south-facing wall, in a sheltered town garden or near the sea.
• Light, free-draining sandy or loamy soil, acid to neutral. On chalky soil the leaves turn yellow.
• Rather dry than wet: it dislikes wet roots in winter.
• Sheltered from cold easterly winds. Outdoors, allow a spread of about 6 m.
• In a pot: a large container with drainage holes and lime-free compost.

Light

Sun

Soil type

Sand or loam

Acidity

Acid or neutral

Moisture

Dry or normal

Size

8 m tall, 6 m wide

Hardiness

Half hardy (to -8 °C): protect it in harsh winters

Goes well with

• Camellia: Also likes lime-free soil, flowers at the same time and is happy to overwinter cool.
• Olive: Silvery leaves and the same Mediterranean feel on the patio.
• Rosemary: Evergreen and scented, for the same sunny, dry spot.
• Crocus: In open ground under the tree: purple crocuses flower at the same time as the yellow mimosa.

Silver wattle: when and how to plant it?

Plant in May–June.

1. Plant or repot in May–June, once there is no more risk of night frost: that gives it time to root in before winter.
2. Outdoors: dig a hole twice as wide as the root ball and loosen heavy soil with some coarse sand.
3. First drive a sturdy stake into the hole, on the windward side, then set the plant next to it.
4. Plant the root ball at the same depth as in the pot and firm the soil.
5. Water generously, preferably with rainwater, and afterwards only in dry spells.
6. In a pot: a layer of gravel at the bottom and lime-free compost, for example multi-purpose compost mixed with ericaceous compost.

Care

Water

In a pot, regularly in summer, with rainwater; let the top few centimetres dry out between waterings. Sparingly in winter, but never let the root ball dry out completely.

Feeding

Little needed: it fixes its own nitrogen. From April to August, give pot-grown plants an occasional weak dose of feed for acid-loving plants.

Repotting

Every two or three years, after flowering in April–May, into a slightly larger pot with fresh lime-free compost.

Support

A sturdy stake, even in a pot, as the crown catches a lot of wind.

Cut flowers

Cut branches when the first balls open and put them straight into lukewarm water.

Tip: Water with rainwater and use lime-free compost: tap water is often limy and turns the leaves yellow. Prune only straight after flowering, or you will remove next year’s buds.

Silver wattle: when to prune it?

Pruning months: April.

When: Straight after flowering, in April. Pruning later costs flowers: next year’s buds are already formed in summer.

How:

• Cut flowered shoots back to just above a few leaves or a side shoot.
• Remove frost-damaged, dead and crossing branches.
• In a pot, keep it compact by shortening long shoots by a third to a half.
• Remove suckers around the base, as low down as possible.

Caution: Do not prune in autumn or winter: you would remove the flower buds.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

The seed has a hard coat: pour hot water over it and leave it to soak overnight. Sow indoors in spring at about 20 °C.

Suckers

In spring, detach a sucker with a piece of root and pot it up in lime-free compost.

Silver wattle: how does it get through the winter?

Hardy to −8 °C: protect in harsh winters.

• Moderately hardy, to about −8 °C; young plants and the flower buds are more sensitive.
• Outdoors: choose the most sheltered spot in the garden and put a thick mulch over the roots. In severe frost you can wrap the crown temporarily in a double layer of fleece.
• In a pot: overwinter in a light, frost-free place, such as a cold greenhouse, an unheated conservatory or a cool, light hallway. A heated living room is too warm and too dark.
• It can take a light night frost: only bring it in when real frost arrives.

Diseases and pests

• Yellow leaves: Yellow leaves with green veins: the soil or the water is too limy. Use rainwater and lime-free compost.
• Frost damage: Brown leaves and dead twigs after a harsh winter. Wait until May, then cut back to healthy wood: it often reshoots.
• Leaf drop indoors: It sheds a lot of leaves if overwintered too warm and too dark. Move it somewhere cooler and lighter.
• Scale insects and mealybugs: Brown scales or white fluffy tufts on the twigs, often during overwintering. Wipe them off with a cloth or soft brush and water with a little soft soap.
• No flowers: Too little sun or pruned in autumn. Move it into more sun and prune only after flowering from now on.

Through the year

• January: Overwintering: light and frost-free, little water. The flower buds swell.
• February: Flowering starts. Cut branches for the vase.
• March: Full flower and scent. Bees on mild days.
• April: Prune after flowering. Repot if needed.
• May: Plant or move outside after the last night frost. Feed.
• June: Planting. Water in dry spells.
• July: Growth. Water pot plants and feed occasionally.
• August: Next year’s flower buds are forming. No more pruning.
• October: Reduce watering. Get the fleece ready.
• November: Bring pot plants in when frost threatens, somewhere light and cool.
• December: Overwintering. Little water, but never bone dry.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• It is called mimosa, but the true genus Mimosa is a different plant, such as the sensitive plant, whose leaflets fold up when touched.
• Each fluffy ball is not a single flower but a head of dozens of tiny flowers with long stamens.
• Around the Mediterranean, including Portugal and southern France, it has naturalised so widely that it is regarded as invasive; in Belgium the frost keeps it in check.