Gadenin日本語Get the appThree methods, and what each one is for
Seed is how the plant propagates itself, whether you help or not. A mature four o'clock sets hundreds of hard black seeds and drops them under itself, so you will have volunteers next spring regardless. Collecting seed deliberately is worth doing when you want to move the plant to a new part of the garden or share it, but be clear that seedlings vary in color and a batch saved from a mixed group will drift toward the darker shades over a few generations.
Tuber division is the method that keeps a color. The tuber is a clone of the plant that made it, so a division from the plant with the flowers you liked will produce exactly those flowers. It also flowers far earlier than a seedling, because it starts the season with stored reserves and does not have to build a plant from scratch. In a cold garden where the tubers are lifted anyway, division costs nothing extra.
Cuttings are the backup. They root readily in warm weather and are useful when you want a copy of a particular plant part way through the season and do not want to disturb the tuber, or when you want to carry a plant through winter on a windowsill instead of storing a heavy tuber.
| Method | Best time | Comes true to color | Flowers in year one |
|---|---|---|---|
| Saved seed | Collect through late summer and autumn | No, colors vary and drift | Yes, about eight to ten weeks after germination |
| Tuber division | At planting time in spring, before growth starts | Yes, exactly | Yes, several weeks earlier than seedlings |
| Softwood cuttings | Early to mid summer, from non-flowering shoots | Yes, exactly | Sometimes, late in the season |
Saving and storing seed
Seed forms behind each faded flower and ripens over roughly two to three weeks. It is ready when it is hard, deeply wrinkled and fully black; a seed that is still green or leathery will not germinate and will not ripen off the plant. Ripe seed detaches with almost no pressure, which is exactly why so much of it ends up on the ground.
Collect by cupping a hand under a branch tip and running your fingers along it, catching what falls. Go over the plant every few days from mid summer on. Spread what you collect on paper somewhere dry and airy for a week, then store in a paper envelope somewhere cool and dry. Label it with the color of the parent plant and the year even though the color is not guaranteed, because it still tells you something.
Seed stays viable for several years in dry storage, so a single good collection covers you for a while. Wear gloves and keep the envelope out of reach of children; these are poisonous seeds that happen to look like something worth eating.
Dividing tubers and taking cuttings
Divide at planting time in spring, when the stored tuber is dry, firm and just beginning to show pink growth buds at the crown. Do not divide in autumn when you lift; the cut surfaces will not heal reliably in storage and the whole piece is likely to rot. A tuber that has been in the ground two or three years is large enough to split into two or three pieces, and each piece must carry at least one visible growth bud to be worth anything.
Cut with a clean sharp knife, straight through, and leave the pieces on a bench in a dry airy place for two or three days so the cut surfaces dry to a firm skin before they go into soil. Plant with the crown two to three inches (5 to 8 cm) below the surface, and do not water heavily until you see shoots; a freshly cut tuber in wet cold soil is the easiest way to lose it.
For cuttings, take six inch (15 cm) shoot tips in early to mid summer from growth that is not carrying flower buds. Strip the lower leaves, cut just below a node, and put them in damp gritty potting mix somewhere warm and bright but out of direct sun. They root in two to three weeks at soil temperatures around 70F (21C). A rooted cutting will make a small tuber of its own by autumn, which can then be stored like any other.
- Collect seed only when it is black and hard Run your fingers along the branch tips every few days from mid summer. Take only fully black, wrinkled, hard seeds; green or soft ones will never germinate. Dry on paper for a week, then store in a labeled paper envelope somewhere cool and dry, out of reach of children.
- Split the tuber in spring, not autumn Wait until you can see pink growth buds on the crown. Cut cleanly so each piece has at least one bud, then leave the pieces to dry for two or three days until the cut surfaces have skinned over.
- Plant divisions shallow and dry Set each piece with the crown two to three inches (5 to 8 cm) deep in well-drained soil and water once, lightly. Hold off further watering until shoots appear, usually within two to three weeks in warm soil.
- Root cuttings in early summer Take six inch (15 cm) non-flowering tips, strip the lower leaves, insert into damp gritty potting mix, and keep at around 70F (21C) in bright indirect light. Expect roots in two to three weeks and a usable young tuber by autumn.
Wear gloves for all of this. The sap irritates some skin, and you will be handling a lot of cut tissue when dividing tubers or taking a batch of cuttings.
What to write down
Record which parent plant each batch of seed came from and what color it was, then next season record what colors actually came up from it. Two years of that and you will know how much color drift your own garden produces, which is more useful than any general statement about the species.
For divisions, note the date you split each tuber, how many pieces it gave, and how long each took to show a shoot. Slow or failed pieces almost always trace back to being cut without a growth bud or planted before the cut had dried, and the record makes that obvious. Note the first flowering date of divisions alongside that of seedlings sown the same spring, since the size of that gap is the whole argument for keeping tubers.