Gadenin日本語Get the appFlowers on bare wood, before the leaves
The deciduous magnolias flower on bare wood. The buds swell on leafless branches through late winter, open before a single leaf appears, and the leaves push out only as the petals fall. This is what makes the display so striking, and it is also what makes it so vulnerable, because there is no foliage at all to buffer the flowers from cold, wind or sun.
It also means the flower buds you can see on the tree in autumn and winter are next spring's display, already made and already committed. They are large, furry and blunt, quite distinct from the small pointed leaf buds. Once you can tell them apart you can count next year's flowering from a winter's day, and you can also see immediately what a piece of pruning would cost you.
The evergreen magnolias work differently, flowering in summer on the current season's growth and among full foliage. They are far less exposed to frost, flower over a long season rather than in one burst, and the advice below about frost timing applies mostly to the bare-wood kinds.
| Bud type | Appearance in winter | What it becomes |
|---|---|---|
| Flower bud | Large, fat, blunt, covered in gray-brown fur | One flower next spring |
| Leaf bud | Small, slim, pointed, tight to the stem | A shoot and leaves |
| Blind or shed bud | Shriveled or missing where one stood | Nothing, usually from drought last summer |
Frost turns open flowers brown overnight
A single night of frost on open flowers is enough. The petals collapse, turn translucent brown, and hang on the tree for a week or two looking like wet paper. The tree itself is unharmed and will flower normally the next year, but the season is finished, and there is nothing to be done once it has happened.
The damage is a thaw problem more than a freeze problem. Frozen petals that warm slowly, in shade, often recover. Petals that go from frozen to full sun in a few minutes rupture. This is precisely why an east-facing or fully exposed position is the wrong one, and why the same variety survives untouched on the west or north side of the same garden.
Unopened buds are much tougher than open flowers. A frost that ruins a tree in full bloom will often pass harmlessly over a tree still in tight bud, which is why the later-flowering kinds are more reliable in cold gardens. If a hard night is forecast when the tree is just opening, throwing a light cover over a small tree overnight and removing it before the sun reaches the branches genuinely works. On a mature tree there is no practical protection, and the site choice made at planting is the only defense you have.
Do not cut off frosted flowers in the hope of a second flush. There is not one. The browned petals drop by themselves within two or three weeks.
The three reasons a magnolia has no flowers at all
Youth is the commonest and the least satisfying answer. Seed-raised magnolias can take ten to twenty years to flower; grafted or layered plants usually start within three to five years of planting. If your tree came from a nursery in flower or in bud, it is grafted, and patience is measured in a few seasons rather than a decade.
Pruning is the second reason, and it is self-inflicted. Because the flowers form on wood made the previous summer, any winter or spring tidying removes exactly the buds you were waiting for. A magnolia that is shaped every year will never flower properly, no matter how well it is fed.
The third is the site: too much shade, or a dry late summer that stopped bud formation. Buds for next spring are set from midsummer onward, so a hot, dry late summer affects the display you get the following spring. Watering in late summer is the one intervention that reliably raises next year's flower count.
- Check the age and origin of the plant Look for a graft union at the base of the stem: a swollen or crooked joint, or a change in bark texture. A grafted tree should flower within a few years of planting. If there is no union and the plant came as a seedling, it may simply be too young, and no treatment will speed it up.
- Count the flower buds in winter Go out on a still winter day and look for fat, furry buds on the previous summer's growth. If they are there, the tree is going to flower and the only question is whether frost lets it. If there are none, the failure happened last summer, not this spring.
- Review what you cut and when If any branches were shortened after midsummer or during the winter, that is where the flowers went. Stop pruning entirely for two seasons and the tree will normally flower again on its own.
- Water through late summer Give an established tree a slow, deep soak every ten days through any dry spell from midsummer to early autumn. This is the period when flower buds are being formed, and drought at that point is the commonest cause of a bare spring on an otherwise healthy tree.
After the flowers go over
Deadheading is neither necessary nor practical on a magnolia. The spent petals drop cleanly, and on a mature tree there is no way to reach them anyway. Leave them; they break down quickly on the mulch below.
The window immediately after flowering is not the time to prune, despite what is true of most spring-flowering shrubs. Magnolias bleed and heal badly from cuts made in spring, and the correct window is midsummer. Let the leaves come out and the tree get into full growth, and deal with any shaping months later.
Records that pay off
Write down the date the buds started to break, the date the first flower opened, and the low temperature on any night the flowers were open. After three seasons you will know whether your site loses flowers most years, occasionally, or almost never, and whether it is worth adding shelter on the windward side.
Note the number of flower buds visible each winter as well, even roughly, as few, moderate or many. Comparing that against the previous summer's rainfall is the fastest way to prove to yourself that late-summer watering matters.