Gadenin日本語Get the appSeed gives you variation, and that is the point
Globe artichokes raised from seed do not come uniform. Out of a batch you will get plants with fat, tight, well-filled buds and plants with small, spiny, open ones, along with everything in between. That is normal for this crop, and it is why sowing is only the first half of the job.
The plan is to sow more than you intend to keep, grow them all on, then judge them on the first buds they produce and keep only the best. Those keepers become the permanent plants, and every replacement afterwards comes from offsets off them rather than from seed. That way you propagate the good ones instead of rerolling the dice each time.
Sow roughly twice the number of plants you want in the ground. Given how much space a mature plant takes, three or four keepers is plenty for most gardens, so eight to ten seedlings is a sensible batch.
| Stage | Target | Why |
|---|---|---|
| Seeds sown | Twice the plants you want | Half will be worth discarding on bud quality |
| Sowing depth | Half an inch (1 cm) | Large seed; too shallow and it dries out |
| Germination temperature | 68 to 77F (20 to 25C) | Cool compost gives slow, patchy germination |
| Days to emerge | 10 to 20 days | Slower and more uneven than most vegetables |
| Pot size before planting out | 4 to 5 in (10 to 13 cm) | Strong taproot needs depth before it goes out |
Seed is large and easy to handle. Sow two per cell and pinch out the weaker seedling rather than trying to prick apart tangled roots later.
Sowing indoors, well before the last frost
Start indoors or under cover about eight to ten weeks before your last expected frost. Artichokes are slow off the mark and need a long run to make a plant big enough to be worth putting out, and starting late is the main reason first-year plants produce nothing at all.
Use deep cells or small pots rather than shallow trays. The seedling puts down a strong taproot early, and a root that hits the bottom of a shallow tray and circles never fully recovers.
- Sow into deep cells or 3 inch pots Fill with a free-draining seed-starting mix, sow two seeds per cell about half an inch (1 cm) deep, and water from below so the surface is not compacted.
- Keep the compost at 68 to 77F (20 to 25C) A heated propagator or a warm indoor spot gets germination going in ten to twenty days. Below 60F (15C) germination becomes slow and erratic.
- Move to full light as soon as they emerge Seedlings kept warm and dim stretch immediately. Get them into the brightest place you have and drop the temperature a few degrees once they are up.
- Pot up before they check Move each seedling into a 4 to 5 inch (10 to 13 cm) pot when the second pair of true leaves appears. A checked artichoke seedling sulks for weeks.
- Harden off over two weeks Increase outdoor exposure gradually before planting out. These are large, soft-leaved seedlings and they scorch badly if they go straight from indoors into full sun and wind.
Do not sow direct into open ground in a cool climate. Germination is too slow and uneven, and slugs take the seedlings before you ever see them.
The cold trick that makes first-year plants flower
Globe artichokes normally need to experience a winter before they will produce buds. That is why a plant sown in spring and planted out in early summer usually gives nothing at all in its first season and only starts cropping the following year.
You can shortcut this. A young plant that experiences a spell of genuinely cool weather while it is still small is fooled into behaving like a second-year plant and will often bud in its first summer. The technique is to expose the hardened-off seedlings to roughly ten to fourteen days at 50F (10C) or below before planting them out.
In practice this usually means planting out earlier than feels comfortable, once hard frost has passed but while nights are still cold, and letting the weather do the chilling. It is worth doing, but treat any first-year buds as a bonus. The plant's real job in year one is to build a crown.
| Approach | What happens in year one | Best for |
|---|---|---|
| Sow early, chill young plants | Often a small crop of buds | Anyone impatient for a first taste |
| Sow early, no deliberate chill | Leaf growth only, crop next year | Simplest and perfectly reliable |
| Sow late in the season | Small plant, no crop, weak first winter | Not recommended in a cool climate |
| Start from an offset instead of seed | Crops in the following season, true to the parent | Replacing plants once you have good stock |
Do not chill seedlings by putting them in a refrigerator. It is the young plant standing outdoors in cool air that responds, and a sealed cold box just rots the leaves.
Planting out and choosing the keepers
Plant out after the last hard frost, into ground that has been dug and manured deeply, at three to four feet (90 to 120 cm) apart. Plant to the same depth the seedling sat at in its pot, never deeper, because a buried crown rots. Water in well and keep them watered through their first summer, which is when the root system that carries the plant for the next four years is built.
Then judge them. When the first buds appear, on the same plants in the same conditions, the differences are obvious: some plants give fat heads with tightly packed, blunt scales, others give small, loose, spiny ones. Keep the good ones, dig out the rest, and give the space to the keepers.
From that point on you never need to sow again. Every replacement plant comes as an offset from a keeper, which means the quality you selected carries forward instead of being rerolled.
- Prepare the ground deeply first Dig in a heavy dressing of well-rotted manure over the whole planting area. This is a four-year plant and the only easy chance to get organic matter into the root zone is before it goes in.
- Plant at final spacing straight away Three to four feet (90 to 120 cm) each way. Do not interplant closely with the intention of thinning later; disturbing an artichoke root system sets the survivors back badly.
- Water through the whole first summer First-year plants have not yet rooted deeply and dry out quickly. Regular deep watering in the first season is what produces a crown strong enough to survive its first winter.
- Mark and record every plant Note the sowing date, the planting date and a number for each position. When you compare first buds, you need to know which plant produced which head.
- Cull on bud quality, not leaf size Dig out the plants with small, loose or very spiny heads once you have seen their first buds. A vigorous-looking plant with poor buds is taking space from a good one.
Record which numbered plant gave the best terminal bud and how early it arrived. Those notes are what tell you which crown to take offsets from in a couple of springs' time.