Gadenin日本語Get the appThe pods explode, and they are not subtle about it
About a fortnight after a flower fades, a fat green pod swells in its place, roughly the size and shape of a small olive, covered in fine hairs. As it ripens, tension builds in five segments of the pod wall until the slightest touch, a passing hand, a bird, a heavy raindrop, makes the whole thing spring apart and curl violently inward, flinging its seed six to ten feet in every direction. It is loud enough to feel and it is genuinely startling the first time.
This is the plant's dispersal mechanism and it is extremely effective, which is why a single plant left to its own devices seeds a wide patch of ground. It is also charming, and if there are children in the garden they will find the plant long before you point it out to them. There is no way to disarm it; the only variable is whether the pod goes off in your hand or on the ground.
Telling a ripe pod from an unripe one is a matter of touch. An unripe pod is firm and stays put when you press it gently. A ripe one feels slightly springy and tense, has usually paled a little, and will go off under almost no pressure at all. If you want the seed, work on the pods that are still firm but have started to pale, because a fully ripe one will be gone before your fingers close.
- Cup before you pinch Bring your free hand up underneath and around the pod so it is enclosed, then pinch the stalk with the other hand. If it fires, it fires into your palm. A small paper bag slipped over the pod works even better.
- Bag whole stems for a big harvest Slip a paper bag over the flowering section of a stem, tie it loosely at the bottom, and leave it a week. The pods burst inside the bag and the seed collects at the base. Do not use plastic; it traps moisture and the seed molts.
- Dry and store properly Spread the seed on paper somewhere airy and out of the sun for a week. Store dry and cool in a paper envelope, labeled with the year. Seed stays viable for several years but germinates most reliably in the first two.
- Leave a few pods on purpose If you want the patch to come back on its own, leave three or four pods on one plant to burst where they stand. That is enough for a generous stand of seedlings next spring.
Self seeding, and how to keep it within bounds
Garden balsam self seeds freely and will hold a patch of damp shady ground for years without any help. In many gardens that is exactly what is wanted: the seedlings come up in a mass in late spring once the soil warms, and you thin them to the spacing you want and have a full stand of plants for nothing. They come up where the parent plants stood, plus a broad ring around them and anywhere downhill that water has carried seed.
Where it is not wanted, the control is simple and has to be regular: pick the pods off weekly while they are still small and firm, before any of them can ripen. Miss a fortnight in late summer and several dozen pods go off at once. Removing the plants at the end of the season is far too late, because by then the seed is already in the ground.
Seedlings that do come up where you do not want them pull out easily at the two leaf stage, roots and all, because the root system is shallow and fibrous. Left until they are six inches (15 cm) tall they still pull, but they leave a hole in the bed. Hoeing works too. What does not work is ignoring them, because a plant that reaches flowering size will reload the ground for the following year.
| Stage | What to expect | Your options |
|---|---|---|
| Flower fades | Pod forms in the axil within two weeks | Pinch off now for no seed at all |
| Pod green and firm | Safe to handle, seed not yet mature | Remove, or bag for a controlled harvest |
| Pod paling and springy | Will fire at the lightest touch | Cup in a hand to collect the seed |
| Pod burst | Seed thrown six to ten feet (2 to 3 m) | Expect seedlings there next spring |
| Seedlings emerge | Late spring, in a mass | Thin to spacing, transplant, or hoe off |
Moving self sown seedlings and growing on
Self sown seedlings transplant well when small and badly once they are large. Lift them at the two true leaf stage with a spoon or an old fork, taking as much soil as you can, and set them out at their final spacing of 10 to 14 inches (25 to 35 cm) apart. Water them in and shade them for two or three days with anything to hand, and they carry on without a pause. A seedling moved when it is already 8 inches (20 cm) tall sulks for a fortnight and never quite catches up.
Do not move them into a border and then let them dry out. A newly transplanted balsam has very little root and no reserves at all, and one hard wilt at that stage sets it back a month. Water daily for the first week.
Volunteer seedlings from your own plants will not necessarily look like their parents, particularly the double flowered forms, which throw a mixture of doubles and singles and a range of colors. That is part of the pleasure of letting the patch run, but if you want a matched planting, sow saved seed deliberately and be prepared to pull out the ones that come up wrong.
Cuttings do work on this plant, and shoot tips will root in a glass of water in about a week, but there is little point. Garden balsam is an annual that dies at the first frost, it grows to flowering size from seed in eight to ten weeks, and seed is produced in embarrassing quantity. Save the cuttings technique for something that will live longer than one season.
What to record
Note the date the first pods started bursting and the date the first seedlings appeared the following spring. Those two dates set the whole rhythm of managing this plant in your garden: the first tells you when weekly pod removal has to start if you want to stay in control, and the second tells you when to be out looking for seedlings to thin or move.
It is also worth marking on a sketch of the bed where you let seed fall deliberately. Balsam seedlings are easy to mistake for weeds at the two leaf stage, and knowing that the mass of green in one corner is the stand you wanted rather than something to hoe off saves the patch.