Weigela is a flowering shrub that is not commonly used for bonsai but can create some really interesting and beautiful compositions when good specimens are found.
What makes Weigela such an interesting source material for bonsai is the contrast of its delicate flowers against its craggy bark. Similar to the live vs dead interaction seen with junipers, the contrast of elegance against age can make stunning bonsai compositions.
Weigela plants are widely available for garden nurseries or as 'yardadori', and so they are accessible for bonsai at a low price. They are generally hardy but do have some nuances to get the best out of their flowering capabilities, so let's take a look at how best to care for Weigela bonsai.
- Pests and disease
- Position in the garden
Weigela is a flowering shrub that is commonly used in landscape gardening. It has an upright/spreading growth habit and a wide number of varieties.
In late spring and early summer, Weigela grows trumpet-shaped flowers that vary in color from pinks, reds, and white through to purples and yellows.
Like their leaves, Weigela also has a range of different leaf types. Most commonly they are deep green, but some varieties have a bronze or purple tint and there are also variegated cultivars.
Weigela are deciduous shrubs so can also make a nice winter silhouette when used for bonsai.
Weigela have no specific watering requirements different from other bonsai. The top half-inch of soil should be allowed to dry out between waterings to ensure good oxygenation of the roots. You should avoid overwatering your bonsai.
How and when you prune a Weigela is key to its ability to flower. Flowers will grow on last season's growth, so if you prune your Weigela bonsai in early spring you may be removing flower buds, which will impact the spring display of flowers.
Annual maintenance pruning is best completed in early/mid-summer after the flowers are spent. Trim back elongating shoots to 2 or 3 leaves, or to within the desired silhouette of the tree.
You can apply partial defoliation techniques as part of a mid-summer pruning to help increase branching and fine ramification. To do this, prune off 4 out of every 5 leaves on the tree, so it is left with just 20% of its original foliage mass. This leaf reduction will stimulate the bonsai to grow a second round of branches, which will improve the canopy of your tree.
When it comes to primary development and structural pruning, you can also do this after flowering so you can enjoy the floral display. However, you may find it more beneficial to do your structural pruning in early spring, as the tree will be better able to stimulate interior buds and heal wounds due to the large quantities of stored energy it has from last year's growing season. This will have the downside of missing out on flowering for a year, but if it will set the bonsai up for long-term success I believe that is an acceptable compromise.
Weigela has very brittle branches and can be quite difficult to wire if they have grown much past half a centimeter in diameter. You can try wiring thicker branches, and you can get a very small amount of movement in them, but there is a risk you will snap some along the way.
Fortunately, new growth is malleable and can be wired fairly easily, so long as you are gentle. I'd recommend using aluminium wire when wiring new growth as it is less likely to damage green stems.
Through a combination of directional pruning and wiring young growth, you can create very nice compositions with Weigela.
Weigela bonsai can be found in all shapes and sizes, particularly if they are collected as 'yardadori'. They are commonly used as informal upright bonsai and can also be well suited to cascade designs thanks to their spreading growth habit.
Weigela grows very fine, wirey roots, and can stay in a bonsai pot for many years without repotting.
If you notice the soil is compacted on top and no longer allowing water to flow through, you may need to repot the tree. Equally, if the soil has started to break down and decompose you should repot your bonsai, removing as much of the decomposed soil as you can in the process.
Repotting should be performed in late winter or early spring, just as buds are starting to push. You should avoid summer or autumn repotting, as this increases the risk of ill effects on the tree.
The soil you use should be a modern bonsai substrate that allows good drainagae of water. My are planted in akadam, but other options include mixes of lava, pumice, pine bark or other aggregate components.
Fertilization is key to providing your bonsai with required micronutrients, as well as stimulating growth in developmental pieces of material.
Fertilization should always be tailored to the stage of development your bonsai tree is at. Trees in early development will benefit from heavy fertilization to drive foliage and root growth, whereas bonsai in refinement should be fertilized lightly to avoid coarse growth that ruins the taper of fine branches.
Pests and disease
Weigela are generally healthy plants that do not suffer from any particular health issues. They are still vulnerable to common problems such as spider mites or fungal infections, but these can be treated in the same manner you would with any other deciduous bonsai.
Position in the garden
Weigela bonsai enjoy growing in full sun or partial shade. They are frost-tolerant and ok with temperatures of -5°C to -10°C, depending on the age of the plant and the size of the pot.
If there are concerns about overwintering your bonsai consider healing it in with mulch or storing it in a wind shelter.
Weigela can be propagated in a couple of ways. They root easily from cuttings and can be taken as softwood cuttings in spring or semi-hard cuttings in autumn.
They can also be propagated via seed, which are best planted in autumn.