Gadenin日本語Get the appThe three groups, and how fast each flowers
Garden stock is sold in three broad groups that differ in how long they take from sowing to flowering and how much cold they need on the way. Knowing which group you have decides your sowing date, and getting that wrong is the usual reason a plant grows well and never blooms.
The quickest group behaves as an annual and flowers roughly ten weeks from sowing, given cool conditions. It is the group to grow where summers turn hot early, and it is the one most suited to a spring sowing in a cold-winter garden. It still needs a cool spell to bud properly; it simply needs less of one.
The slowest group behaves as a biennial. It is sown in summer, overwinters as a sturdy young plant, and flowers early the following spring on tall, heavy spikes with the strongest scent of the three. It needs a mild winter or a cold frame, and it repays the wait. Between the two sits an intermediate group, sown in late summer for flowers in early spring, hardier than the annual kinds and quicker than the biennial ones.
None of these are cultivar names, and you do not need cultivar names to shop sensibly. A seed packet will always tell you the sowing season and the weeks to flowering, and those two numbers place it in one of these three groups immediately.
| Group | Sowing to flowering | How it is grown | Suits |
|---|---|---|---|
| Annual, quick flowering | About ten weeks | Sow late winter under cover or earliest spring direct | Cold winters, or gardens where summer heat arrives early |
| Intermediate | Roughly four to six months | Sow late summer, overwinter under a frame or row cover | Mild to moderate winters, early spring flowers |
| Biennial | Two seasons | Sow summer, overwinter as young plants | Mild winters, tallest spikes and the strongest scent |
One spike or many: column against branching
The second division is structural and matters more day to day than the first. Column types put everything into a single unbranched spike, sometimes a foot (30 cm) or more of packed florets on one stem. They are the cut-flower form, they are planted close, and they are pulled once that one spike is cut, because there is nothing else coming.
Branching types make a shorter central spike and then a succession of side shoots. They are the garden form. Planted wider, pinched at four or five true leaves, and deadheaded back to a leaf joint, they will flower for six to ten weeks rather than delivering one concentrated burst.
The rule that follows is absolute and worth remembering: never pinch a column type. Removing the growing tip of a single-spike plant destroys the only flower it was going to produce. Pinching a branching type, by contrast, is the single most effective thing you can do to lengthen its season.
| Type | Spacing | Pinch the tip | Season | Best use |
|---|---|---|---|---|
| Column, single spike | Six to eight inches (15 to 20 cm) | Never | One concentrated flush | Cutting for the house |
| Branching, garden type | Eight to twelve inches (20 to 30 cm) | Yes, at four or five leaves | Six to ten weeks with deadheading | Beds, doorways, pots |
| Dwarf, compact branching | Six to eight inches (15 to 20 cm) | Optional | Several weeks | Containers, path edges, windy sites |
Doubles strains and what the packet means by a percentage
The third division is between flower forms. A single flower has four flat petals and is pleasant but light on scent. A double flower is a full rosette of petals, holds on the spike far longer, and carries much more scent. Almost all stock is bought for the doubles.
No strain gives only doubles. Seed sold as a doubles strain produces roughly half double-flowered plants and half singles, and the packet may quote a percentage in the fifty to seventy range. That is not a defect and it is not a marketing dodge; fully double flowers have no functional reproductive parts and cannot set seed, so every generation has to come from the single-flowered plants.
What makes this manageable is that the two kinds look different long before they flower. In a doubles strain the seedlings that will open double are paler, a light yellow-green, with larger and rounder leaves, while the future singles are darker, smaller and narrower. Sort at the two-leaf stage, keep the pale ones, and you can fill a bed entirely with doubles from seed that would otherwise have given you half and half.
Raise about twice as many seedlings as you need plants. Sorting works well but is not perfect, and it costs nothing to be generous at the tray stage and ruthless afterwards.
Night-scented stock is a different plant
Sold under the same common name and often shelved beside the others, night-scented stock is a separate species and behaves nothing like garden stock. It is a thin, sprawling annual with small, dull lilac flowers that stay shut and unremarkable all day, and it looks like a weed in the border. After dark the flowers open and release a scent that is stronger and further-carrying than anything the showy kinds produce.
Grow it for that alone, and grow it accordingly: scatter the seed thinly among other plants right beside a door, a window that is open on summer evenings, or a seat, where it will be hidden by day and unmistakable at night. It is direct sown where it is to flower, needs no support, no pinching and no feeding, and it flowers in a few weeks from sowing. Sowing a small pinch every three or four weeks keeps it going through the summer.
The two are best grown together. The showy doubles supply the spikes you look at and cut; the night-scented species supplies the smell that reaches the far end of the terrace after dark. Neither does the other's job.
Choosing, and writing down what suited you
Match the group to your winter first, then the structure to your purpose. Cold winter and cutting in mind means an annual column type sown under cover in late winter. Mild winter and a scented doorway means an intermediate or biennial branching type sown in late summer and overwintered. Containers on a step mean a dwarf branching type and a night-scented sowing tucked in among them.
Record which group each batch belonged to alongside the sowing date and the date of first flower, because the phrase on the packet is easy to forget and the behavior is not. Two seasons of that record will tell you which of the three groups actually performs in your garden, and after that the choice stops being guesswork.