Gadenin日本語Get the appThe shape of the season
A four o'clock grown from seed does everything in one season and does it fast. Germination in warm soil, then eight to ten weeks of pure growth in which the plant goes from a seedling to a knee-high bush and puts down a tuber, then flowering every evening from mid summer until the frost kills the top growth. There is no rest period and no second flush to wait for.
An overwintered tuber compresses the front half of that. It shoots as soon as the soil warms, reaches full size in perhaps six weeks, and is flowering well before the seedlings sown at the same time have made their first bud. In a cold garden that difference of several weeks is the reason to bother lifting and storing.
The single most common scheduling mistake is treating the growth phase as though nothing needs doing. That is exactly when the spacing decision has to be made, because a plant that is a foot (30 cm) across in early summer will be a yard (90 cm) across by the time it flowers, and by then it is too late to move its neighbors.
| Stage of season | Main job | Decision to make |
|---|---|---|
| Late winter to early spring | Check stored tubers for softness; nick and soak seed if starting indoors | Seed, stored tuber, or both |
| After the last frost, soil above 65F (18C) | Sow direct or plant out tubers and started seedlings | Where each plant goes, given three feet (90 cm) of eventual width |
| Late spring | Thin seedlings hard; clear self-sown volunteers you do not want | Which volunteers to keep and which to pull |
| Early summer | Deep weekly watering; stop all feeding; take cuttings if wanted | Whether growth is going to leaf rather than bud |
| Mid summer | First flowers open at dusk; shorten sprawling branches once | Whether the plant is in the right place to be enjoyed in the evening |
| Late summer into autumn | Strip seed weekly; collect what you want to keep | How much self-seeding you are willing to have next spring |
| First hard frost | Cut the blackened top growth back to six inches (15 cm) | Lift the tuber or leave it in the ground |
| Winter | Cure lifted tubers, then store dry at 45 to 55F (7 to 13C) | Check monthly and discard anything soft |
The four decisions in order
The first decision is how to start. Direct sowing after the last frost is simplest and gives strong plants, but flowering begins late in a short season. Starting indoors four to six weeks early brings it forward. Planting a stored tuber beats both by a wide margin. Most gardens end up doing all three at once, and that is fine.
The second is spacing, taken in late spring while everything is still small. Thin to 24 to 36 inches (60 to 90 cm) between plants and be ruthless about it. A crowded row of four o'clocks flowers less than a thinned one and shades out whatever you planted in front of it.
The third is seed, taken from mid summer onward. Strip the hard black seeds weekly and you keep control of the plant. Let them drop and you will have a carpet of seedlings under the plant next spring and outward from it every year after that. Neither is wrong, but choose deliberately rather than discovering the answer when the seedlings come up next spring.
The fourth is winter, taken at the first hard frost. Where the ground freezes, lift the tuber. Where it does not, cut the top back, mulch, and leave it; the plant will come back larger and flower earlier. In borderline gardens with heavy wet soil, lift, because winter wet kills more tubers than winter cold does.
Lifting and storing in a cold garden
Wait for the first hard frost to blacken the foliage. That frost is the signal, not a date, and it does the plant no harm because the tuber is well below the surface. Cut the top growth back to about six inches (15 cm) so you have something to hold, then dig a wide circle a foot (30 cm) out from the crown and lever the whole thing up rather than pulling on the stem.
The tuber is bigger than you expect, dark-skinned outside and pale inside, and on a three-year-old plant it can be the size of a large parsnip or bigger. Shake off the loose soil but do not wash it. Leave it somewhere dry, airy and frost-free for a week to cure, then pack it in a box of dry sand, vermiculite or shredded paper and keep it at 45 to 55F (7 to 13C).
Check the box once a month. Any tuber that has gone soft, smells, or shows spreading dark patches comes out immediately, because rot moves through a packed box over a few weeks. A tuber that shrivels slightly is fine; one that shrivels badly has been stored too warm or too dry and should be moved somewhere cooler with slightly more moisture in the packing.
Label the box clearly. A stored four o'clock tuber looks enough like a root vegetable that it has been mistaken for one, and it is poisonous.
What to write down
The dates that matter are few and they repeat closely year to year: when you sowed or planted, when the first flower opened, and when the frost came that ended the season. Kept for two seasons those three dates tell you exactly how much earlier you need to start next time to get flowering when you want it.
Add the position and final width of each plant, whether it came from seed or tuber, and how many tubers went into store against how many came out sound in spring. That last ratio is the one that tells you whether your storage conditions are actually working, and it is the number nobody remembers without writing it down.