It is relatively easy to grow mimosa trees from seeds. The seeds can be purchased from a garden center or harvested from an existing tree. If a friend or neighbor already has a mimosa tree in the garden, there’s no harm in asking if you can have some of its seeds to grow a new one or find mimosa tree for sale online.
What Are Mimosa Trees?
Also called silk trees, or Albizia julibrissin in Latin, mimosas are medium-sized deciduous trees with airy, fern-like foliage formed of lots of small leaflets. In summer, the crown is topped by fluffy pink flowers with long, extended yellow stamens. Berries are produced in autumn and often last for months, hanging from the branches to provide interest throughout the year.
Silk trees are members of the Fabaceae (pea) family of plants, and the fragrant flowers make them attractive to bees, butterflies, and other pollinators. They are commonly grown as ornamental specimen trees and make a great garden focal point.
What Do Mimosa Seed Pods Look Like?
The seed pods from these trees look a little like pea pods. However, rather than being bright green in color, they are pale brown. Mimosa pods are long and narrow, measuring 10-20cm long and 2-3cm wide. The pods are pretty flat in appearance, with small bulges where potential seeds may be found inside.
Can You Eat Mimosa Seeds?
Some parts of the mimosa tree are edible and even have medicinal uses. Young leaves have an aromatic flavor when cooked and can also be dried to make herbal tea. The flowers can be harvested to add color and a sweet flavor to salads. Persian silk tree flowers are said to relieve insomnia and depression when drunk as tea.
However, mimosa seeds are toxic to humans and pets and shouldn’t be consumed.
When to Harvest Mimosa Seeds
Seed pods begin to ripen on the tree from August to September. The best time to harvest them is in autumn when they are fully ripe. The pods will darken in color as they become ready for harvest, and you’ll notice them start to dry out and fall. Try to gather all the pods you need before the first frost.
Use a sharp set of secateurs to snip the seed pods away from the branches or pick up fallen pods from the ground beneath the tree.
Ensure the pods are dry before opening them to reveal and extract the seeds inside. The easiest way to remove the seeds is to shake the pod gently. Each pod contains between 2 and 12 seeds.
Store the Seeds
Once harvested, the seeds must be safely stored until it’s time to sow them. Wrap them in a cloth or paper bag – don’t use a plastic bag as trapped moisture can lead to rotting seeds – and keep them in a cool, dry, dark place. Avoid storing in a shed where harsh winter temperatures may affect the seeds. A garage or indoor cupboard is perfect.
When to Plant the Silk Tree Seeds
The best time of year to plant mimosas from seed is late spring. Wait until the threat of frost has passed. Alternatively, seeds can be grown indoors and moved outside when daytime temperatures rise above 15ºC.
Where to Plant Mimosa Seeds
Mimosas can thrive in most soil types, including loam, chalk, and sand, as long as the soil is slightly moist but well-drained. They prefer a sunny location sheltered from strong winds. A position in full sun is ideal, but mimosa trees will tolerate partial shade.
Prep the Silk Tree Seeds
For germination to be successful, it’s recommended to take some time to prepare mimosa seeds before planting them. However, prep is relatively straightforward and doesn’t require much effort.
- Take each seed and rub both ends of it with sandpaper or a nail file until the hard outer coating has been breached.
- Soak the seeds in hot, but not boiling, water for 24 hours until the seeds have swollen to around three times their original size.
- Remove the seeds from the hot water and allow them to dry.
Planting Mimosa Seeds
Mimosa tree seeds are most likely to germinate successfully when they are planted in pots. Fill pots with good potting mix and push the seed around 2-3cm deep. Sow one seed per pot and cover with moist soil.
If the temperature is high enough, the pots can get moved outside. Choose a sunny spot against a south-facing wall for best results. A windowsill or greenhouse is fine if the air is still a little chilly during the day. Keep the soil moist but not soggy until you see the seeds begin to sprout.
How Long Does it Take for Mimosa Tree Seeds to Germinate?
Mimosa seeds are quick to germinate in the right conditions. Depending on light levels, temperature, and other conditions, it can take anything from a week to a couple of months to germinate mimosa tree seeds.
As the shoots grow taller, carefully transplant them into larger pots. Once the plant reaches around 30-35cm in height and has produced several leaves, it is ready to plant out in the garden.
Transplant the Trees
Ideally, the mimosa seeds will be ready to be transplanted into the garden by autumn. Aim to plant the trees out at least 6 weeks before the first frost is expected.
Choose a position in full sun or partial shade and ensure the tree has plenty of space to grow into. Mimosa trees can spread up to 4m, so position the seedlings well away from buildings and other trees to allow the roots to spread and air to circulate freely.
Water regularly to keep the soil somewhat moist until the tree has started growing well. Mimosa trees grow quickly in the first few years and saplings often flower in their 2nd or 3rd year. Trees planted in full sun usually have the most abundant show of flowers from June-July.
Caring for the Plant
As a mimosa tree grows and matures it becomes relatively low maintenance. Water the tree sparingly during winter and more often during dry spells of summer weather. Mature silk trees prefer well-drained soil and are drought tolerant, so don’t need to be watered very often.
A Persian silk tree doesn’t generally need pruning. But if you do want to tidy the tree up or keep it to a specific size and shape, this is best done in late winter or early spring before the growing season starts.
While mimosa trees are hardy to most UK winter temperatures, it is worth offering some additional protection against the hardest frosts. Mulch in late autumn to provide the roots with additional insulation.
How Long Does A Silk Tree Take To Grow?
A fully mature mimosa tree can reach up to 8m tall. They take on up to 0.5m each year and reach their ultimate height in 10-20 years, assuming it isn’t aggressively pruned.
Albizia julibrissin makes an attractive addition to any outdoor space and is relatively simple to grow from seed. While a potted nursery mimosa tree is affordable and easy to come by, its quick germination and rapid growth rate make it a popular choice among gardeners who wish to grow a tree from scratch.