How to Sow Mallow Seed: Scarifying, Depth and Why It Hates Transplanting

Sow direct: the taproot makes transplanting a losing move

Mallow puts down a thick, pale taproot in its first two or three weeks, and that root is the whole plant's drought insurance for the rest of its life. Break the tip in a module tray and you get a plant that sulks for a month, flowers short and thin, and burns out in the first hot spell instead of standing through the season. Sow where it is to grow and you get a plant that never wilts once established.

Sow the seed a quarter inch (6 mm) deep in loose soil and firm it down with the flat of your hand. Any deeper and the seedling exhausts itself before it reaches light; any shallower and the hard seed coat sits dry on the surface and never swells. Make a hole with a pencil or a finger tip and drop the seed in rather than scattering, because scattered seed germinates at three different depths and comes up over three weeks.

If you must start under cover, use deep root trainers or four inch (10 cm) pots rather than cell trays, sow two seeds per pot, and get them into the ground before the plant is four inches tall. Past that size the root is already circling and you are better off sowing again outside.

1. Break the seed coat before sowing Mallow seed is a flat, hard-shelled nutlet that can sit in damp soil for a month without moving. Rub the seed between two sheets of medium sandpaper for ten seconds, or soak it in warm water overnight until the seeds swell and sink. Treated seed comes up in ten to fourteen days instead of three to six weeks.
2. Sow two seeds per station, thin to one Germination on saved or older seed runs around sixty percent. Sow two seeds an inch (2.5 cm) apart at each station and pinch out the weaker seedling at the true-leaf stage. Pinch, never pull, or you lift the neighbor's root with it.
3. Firm and water once, then leave it Water the bed thoroughly right after sowing and then let the surface dry between waterings. Mallow seed rots in permanently wet ground far more readily than it dries out, and the seedlings damp off in still, saturated soil.

Do not sow into freshly manured or heavily fed ground. Rich soil gives you a soft, six foot (1.8 m) plant that splits open at the base in the first storm. Mallow flowers best and stands upright in ordinary, even poor, well-drained soil.

Soil temperature decides how long you wait

Mallow germinates over a wide range but slowly at the cold end. Push a soil thermometer two inches (5 cm) into the bed in the morning, before the sun has been on it, and use that reading rather than the air temperature. Sowing into cold ground does not kill the seed, it just leaves it sitting there for the slugs.

The practical window opens once the soil holds above 55F (13C) overnight and the last frost has passed. Seedlings tolerate a light frost but a hard one cuts them off at the stem.

Spacing: it fills far more ground than the seedling suggests

A first-year mallow looks like a modest rosette until midsummer, at which point it throws up branching stems three to four feet (90 to 120 cm) tall and nearly as wide. Plants set at a foot apart shade each other's lower leaves, hold damp air in the middle of the clump, and give hollyhock rust exactly the conditions it wants.

Set the final spacing at twenty-four inches (60 cm) each way and accept that the bed looks empty in the first half of the season. Air moving through the base of the plant is the single cheapest disease control you have.

In a container, depth matters more than diameter. A twelve inch (30 cm) deep pot holds a mallow far better than a wide, shallow bowl of the same volume, because the taproot goes down rather than out.

Thinning, and telling a mallow seedling from a weed

Mallow seedlings are distinctive once you know them. The two seed leaves are heart-shaped with a small notch at the tip, and the first true leaf is round to kidney-shaped with a scalloped, crimped edge and a long stalk that joins near the center of the leaf. Later leaves become shallowly lobed, like a small ivy leaf, and the whole plant carries fine hairs that catch the light.

Thin in two passes. Take the bed down to six inches (15 cm) apart when the first true leaves are open, then to the final two feet (60 cm) when the plants are four to six inches tall. Two passes let you keep the strongest plants rather than whichever seedling happened to be spaced right.

1. First pass at the true-leaf stage Pinch out doubles and anything obviously weak, leaving one plant every six inches (15 cm). Do this in the evening so the survivors are not standing in disturbed soil through the heat of the day.
2. Second pass at four to six inches Take the row down to two feet (60 cm) apart. Keep the plants with the shortest gap between the leaf stalks, not the tallest ones. A stretched seedling has been reaching for light and will flop later.
3. The thinnings are worth eating Young mallow leaves are mild and mucilaginous, closer to a young lettuce than a herb. Rinse the thinnings and use them raw in a salad or wilted, the same day. They do not keep.

What to write down at sowing time

Mallow is easy to lose track of because the plants that come up on their own next year look identical to the ones you sowed. A short sowing record turns the second season from guesswork into a decision.

Note the position on a sketch of the bed as well as the date. Volunteers will appear a few feet away, and knowing where you deliberately put a plant is the only way to tell a seedling you want from one you should hoe off.