Gadenin日本語Get the appFlowers on bare wood, and what that costs
The whole character of this tree comes from flowering before leaf-out. In early spring the fat, felted gray buds that have sat on the twigs since the previous summer split and open into white flowers of six tepals, faintly fragrant, often with a thin pink stain at the base, carried on a completely bare framework. There is no foliage to soften or hide them, which is why a well-grown tree stops people in the street.
The cost is that the flowers are exposed at the most unstable time of year. Every bud you can see in late winter was formed the previous summer and has already survived the winter; nothing you do now adds to their number. From bud break to petal drop, roughly two to three weeks, the display is entirely at the mercy of overnight temperatures.
Understanding this changes what you worry about. Cold in midwinter is irrelevant to a tree hardy to -25F (-32C). A single clear night at 28F (-2C) during flowering is not.
| Stage | What is happening | What you can affect |
|---|---|---|
| Previous summer | Flower buds form on ripening wood | Water in drought, do not overfeed |
| Autumn and winter | Buds sit dormant, felted and gray | Nothing, and that is fine |
| Late winter | Buds swell and lose the felted scale | Count them, watch the forecast |
| Bud break | Tepals show white, most vulnerable point | Cover small trees on frost nights |
| Full flower | Two to three weeks if mild | Enjoy it, record the date |
| Petal drop | Tepals fall, leaves push out | Clear fallen tepals from wet ground |
Frost turns open flowers brown overnight
Frosted magnolia flowers do not look frost-damaged at dawn. They look translucent and slightly limp. By afternoon they are brown, papery and hanging, and within two days they drop. There is no recovery and no treatment; the season's display is over, though the tree itself is entirely unharmed and will flower normally the following spring.
The variable you can influence is thaw speed. Flowers that warm slowly, in shade, frequently survive a night that destroys the same flowers on a tree in full early sun. This is why the aspect chosen at planting does more for the display than anything you do afterwards, and why the tree on the shaded side of a garden often outperforms the one in the open.
On a small tree, a light sheet or row cover thrown over on a night of forecast frost and removed before the sun reaches the branches genuinely works. On a mature kobus magnolia at 30 feet (9 m) there is nothing practical to be done. Accept the lost year when it comes; it is a weather event, not a fault in your growing.
Do not cut off frost-browned flowers as a tidying job on anything you would need a ladder for. They fall on their own within days, and every cut on a magnolia is a wound that seals slowly.
A tree with no flowers at all: the four causes
There is an important distinction between a tree that flowered and lost the flowers to frost, and a tree that produced no flower buds at all. The first is bad luck. The second has a cause, and it is nearly always one of four.
Work through them in order. Age is by far the most common answer and the hardest one to hear, because the only remedy is time. A seedling kobus magnolia commonly takes 10 to 15 years to flower and sometimes longer, and no amount of feeding, pruning or root treatment shortens that.
If the tree is clearly old enough and still bare, look for a pruning history, then shade, then drought stress in the previous late summer. Between them those four explain almost every case.
- Age, first and most likely A tree raised from seed flowers when it is ready and not before, typically after 10 to 15 years and occasionally past 20. Grafted stock flowers far younger. If yours came as a small unbranched whip and has never flowered at eight years old, it is almost certainly a seedling and simply not mature. Keep it watered and leave it alone.
- Pruning, which removes next spring's flowers Every flower bud for the coming spring was set on the wood by late the previous summer. Anyone who shortened the shoots in autumn or winter, however lightly, cut those buds off. A tree that is trimmed annually for shape will never flower well, and the fix is to stop cutting for two full seasons.
- Not enough light Flower buds form on wood that ripened in good light. A tree overtopped by a larger neighbor, or squeezed against a north wall with no sky above it, produces long thin shoots and few buds. It needs full sun for most of the day, with the morning-shade caveat that protects the open flowers from fast thawing.
- Drought in the bud-setting period A tree that was seriously dry in late summer sets fewer buds, and you find out the following spring. If you had a hot dry end to the season and thin flowering followed, that is the connection. Deep watering in late summer, not spring, is what prevents a repeat.
After the flowers go over
Do nothing. The tepals fall, the leaves push out, and the tree gets on with the growing season. There is no deadheading job on a magnolia, no cutting back, and no post-flowering feed. This is the moment when gardeners used to roses reach for the pruners, and it is the single most damaging habit you can bring to this tree.
Some of the flowers set seed, and by autumn you may see knobbly, irregular pinkish fruits that split to show bright red-coated seeds hanging on threads. They are worth looking for and cause no harm. Removing them makes no difference to next year's flowering, so leave them for the birds.
Records that pay off
The date of first open flower, kept year after year, is the most useful number you can hold on this tree. Set beside the overnight lows for that week it tells you, over time, whether your site loses flowers most years, occasionally, or almost never, and that is the difference between an unlucky spring and a badly chosen position.
Alongside it, note the number of visible buds in late winter and how heavy the eventual display was. If the buds were plentiful and the show was poor, that is frost. If the buds were few in the first place, look back at the previous summer's rainfall and at whether anyone pruned.