Gadenin日本語Get the appSow into cool soil, not warm soil
Sorrel is a cool-season perennial and its seed behaves like one. It moves at soil temperatures of 45 to 70F (7 to 21C) and germinates fastest around 60F (16C). That is a much lower window than basil or beans, and it is the reason sorrel can be sown while the bed is still too cold for anything else.
In practice this means two sowing windows. The larger one is early spring, as soon as the ground is workable and no longer sodden; seedlings appear in seven to fourteen days and the plants have a full season to build the root that carries them through winter. The second is late summer, once the worst heat has broken. Sowing into soil above 80F (27C) gives patchy, slow germination and seedlings that bolt before they have made a crown, so skip the middle of summer entirely.
| Window | Soil temperature | Days to emerge | What you get |
|---|---|---|---|
| Early spring | 45 to 60F (7 to 16C) | 10 to 14 | Full first-season crown, light picking by early summer |
| Mid spring | 60 to 70F (16 to 21C) | 7 to 10 | Fastest emergence, still a full season ahead |
| High summer | Above 80F (27C) | Patchy | Avoid: thin stand and early bolting |
| Late summer | Falling through 70F (21C) | 7 to 12 | Small crown that overwinters, real cropping the following spring |
Cover a quarter of an inch and firm it
Sorrel seed is small, flat and brown, roughly the size of a grain of coarse sand. Cover it about a quarter of an inch (5 to 8 mm) and no more. Buried deeper it uses up its reserves before the shoot reaches light, and you get a thin stand you blame on old seed when the fault was depth.
Firming after covering matters as much as the depth. Loose soil dries in a band right where the seed sits, and once that band dries the seed stops for good. Press the drill closed with the back of a rake or the flat of your hand so the seed is in contact with damp soil rather than sitting in an air pocket.
- Draw a shallow drill Run a quarter-inch drill with a stick or the corner of a hoe. A deeper trench collects water and the seed sits cold and wet, which is the commonest cause of a poor spring stand.
- Sow thinly along the row Aim for a seed every half inch (1 cm). Sorrel seed is cheap and the temptation is to pour it, but a dense band is hard to thin without tearing out the ones you want to keep.
- Cover and firm Draw the soil back over, then press it down. The surface should look level and slightly compacted, not fluffy.
- Water with a fine rose A coarse jet washes the covering off and floats the seed into hollows. Water gently and keep the surface damp until the seedlings show.
Sorrel seed keeps its viability for about three years in a cool dry place. Seed older than that germinates unevenly, so sow it twice as thickly and thin harder rather than trusting it.
Thin to 12 to 18 inches and mean it
This is where most sowings go wrong. Sorrel seedlings look tiny and it feels wasteful to pull them out, but a single mature plant makes a clump 12 to 15 inches (30 to 38 cm) across and stays in that spot for four or five years. Left at seedling spacing the plants shade each other, the leaves come small and thin, and you cannot get a knife in to cut them.
Thin in two passes. The first pass, at two true leaves, takes the stand down to about 3 inches (8 cm) apart, which insures against losses to slugs. The second pass, at four or five leaves, goes to the final 12 to 18 inches (30 to 45 cm). Rows can be 15 to 18 inches (38 to 45 cm) apart, which leaves enough room to walk in and cut.
| Stage | Spacing | What to do with the thinnings |
|---|---|---|
| Two true leaves | 3 in (8 cm) | Too small to be worth much; compost them |
| Four to five leaves | 12 to 18 in (30 to 45 cm) | Lift with a little root and transplant, or eat as a sharp salad leaf |
| Between rows | 15 to 18 in (38 to 45 cm) | Leave clear so you can cut without treading on crowns |
Thinnings lifted carefully at four or five leaves transplant well if you water them in and shade them for two or three days. That is the cheapest way to extend a row.
Sowing in containers
Sorrel grows perfectly well in a pot, and a container has one real advantage: it stops the plant seeding itself around the garden. Because the plant is perennial and deep-rooted, the pot has to be bigger than people expect. Give one plant a pot at least 10 inches (25 cm) across and 10 inches deep, which is roughly 3 gallons (12 L) of compost. Anything smaller dries out at midday in summer and the leaves go leathery and bitter.
Sow three or four seeds in the middle of the final pot and thin to the strongest, or sow into a small pot and move it on once it has four leaves. Sorrel resents being potted up late, when its taproot has already run to the bottom, so make the move early or sow direct into the final pot.
What to record from the first sowing
A perennial rewards notes far more than an annual does, because you only get one chance a year to learn anything. Write down the date you sowed, the date the first seedlings broke the surface, and the soil temperature if you took it. Two seasons of that tells you your own sowing window far more precisely than any general advice can.
Also record where each plant ended up, ideally as a rough sketch of the bed. Sorrel dies right back in winter and the crowns are invisible; without a note you will put a fork through them in early spring, exactly when they are about to be the first thing you can pick.