How to Sow Spinach: Soaking, Chitting and Sowing in Warm Weather

Three reasons it germinates badly

Spinach seed is noticeably harder to germinate than other leafy crops. There are three reasons: the seed coat is hard and slow to take up water, germination falls away sharply above 77F (25C), and seed that has been through heat goes dormant. Before worrying about technique, work out which of the three applies.

It germinates best at 59 to 68F (15 to 20C), where it comes up in three to five days. Above 77F the rate drops visibly, and in the high 80s almost nothing comes. Sowing in late summer and getting nothing is a soil temperature problem, not a skill problem.

Too little water is just as common. Spinach takes a long time to absorb water, so a watering that only wets the surface leaves the seed to dry out partway. Until it germinates, not letting the surface dry is the priority.

Decide about resowing at seven to ten days. Seed that has not come by then almost never does. Fix the cause first, then sow again.

The kind of seed decides the treatment

What you need to do is set by what the seed looks like in the packet. There is spiky, husked seed, smooth de-husked seed, and coated or pelleted seed, and each of those germinates more evenly than the one before. If germination is your problem, buying treated seed is the shortest route to solving it.

1. Spiky husked seed The coat is thick and slow to take up water, so an overnight soak helps most. It is cheap and common in older varieties.
2. Smooth de-husked seed The coat has been removed so it takes up water fast and germinates well sown straight. It is also more vulnerable to drying, so the watering afterwards cannot be neglected.
3. Coated or pelleted seed Treated with fungicide or a wetting agent and made larger so it can be sown one at a time. Soaking washes the treatment off, so sow it dry with no pre-treatment.

Soaking coated seed overnight washes the treatment off and makes things worse. If the packet says do not soak, follow it.

Soaking and chitting

Chitted seed dies quickly if it dries after sowing, so only chit when you know you can water it consistently for the following week.

1. Soak overnight Put husked or smooth seed in water at room temperature for half a day to overnight. Beyond twenty-four hours it runs short of oxygen and spoils, so lift it out in the morning.
2. Drain and surface dry Drain in a sieve and blot the surface dry. Sticky seed clings to your fingers and you cannot space it.
3. Chill for two or three days Wrap in damp paper in a sealed box and put it in the fridge. The cold breaks dormancy, which is exactly what fixes poor germination in warm weather.
4. Sow as the root shows Sow when a white root is a millimeter long. Left longer, the root snaps as you sow and that seed dies. Sow on the day you see it.

Sowing measurements

Sow in drills. Press the edge of a board or a cane in to make a drill about half an inch (1 cm) deep with a flat bottom, then drop the seed. A flat bottom puts the seed at one depth so it comes up together. Broadcasting makes thinning hard to judge and leaves the crowns badly ventilated.

Sowing while it is still warm

If the forecast shows a hot spell, delaying by a week is a better decision than sowing anyway. Seed that goes dormant is wasted, and you will be sowing again regardless.

1. Water the bed the day before Soak the bed the day before to cool the soil and settle the moisture. That is more stable than sowing dry and watering afterwards.
2. Shade netting on hoops Put shade netting over the bed on hoops to soften the sun and the impact of rain. Laid on the soil it traps heat, so it has to be raised.
3. Sow in the evening Avoid the heat of the day and let the seed take up water overnight. There is less time before the next watering, so less risk of drying.