Propagating Mallow: Saving Seed and Controlling the Self-Sown Colony

Seed is the only propagation route that works

Mallow is grown from seed and effectively nothing else. Softwood cuttings root poorly and the rooted ones rarely make a plant worth keeping, because the taproot that gives mallow its drought tolerance never forms from a cutting. Division fails for the same reason: there is a single central root, not a clump of crowns, and cutting it usually kills the plant.

This is not a limitation in practice. Mallow comes readily from seed, germinates within a fortnight when scarified, and flowers in its first or second season. A plant grown from your own saved seed will be better adapted to your ground than anything bought in.

The seed head shatters, so collect it before it does

After the flower drops, the calyx swells into a flat, round disc divided into a ring of wedge-shaped segments, each holding one seed. It is green and soft at first, then goes tan and papery, and at that point it breaks apart at a touch and the segments drop straight down around the plant.

The window between ripe and shattered is only a few days, and it is easy to miss because the seed heads sit under the foliage. Check the lowest, oldest seed heads on each stem twice a week from midsummer; those ripen first and tell you the rest are coming.

Collect when the disc has turned pale tan and the segments separate cleanly under thumb pressure but have not fallen. Seed collected green will not store; seed collected a week late is already on the ground.

1. Cut whole stems into a paper bag Hold a paper bag under the stem, cut, and invert the stem into the bag in one movement. Anything that shatters on the way is caught. Never use a plastic bag: any residual moisture will mold the seed within days.
2. Finish drying indoors for a week Spread the heads on a tray in a warm, dry, airy room for seven to ten days. The discs will break up on their own and the flat nutlets fall clear when you rub them between your palms.
3. Winnow and store cool and dry Tip the mix from one bowl to another in front of a fan; the light chaff blows off and the heavier seed stays. Store in a labeled paper envelope in a cool, dry place, not in a sealed jar unless the seed is thoroughly dry.
4. Bag the heads if you cannot check often Tie a paper or fine mesh bag over two or three developing seed heads on the best plant. They shatter into the bag and you collect at leisure, which also stops those particular heads seeding into the bed.

Saved mallow seed stays viable for three to four years if kept dry and cool, though germination drops noticeably after the second year. Label every envelope with the season it was collected; there is no way to tell old seed from new by eye.

It self-seeds hard, and the seed heads are the control point

This is the point on which mallow becomes either a good garden plant or a nuisance. A single well-grown plant produces thousands of seeds, drops them within a couple of feet of the stem, and those seeds sit in the soil for years before germinating. Two seasons of leaving the seed heads on and you have a permanent mallow patch that reappears wherever you dig.

The whole of the control is in one habit: do not let the seed heads ripen unless you want them. Deadheading through the flush, which you are doing anyway if you are picking flowers for tea, removes almost all of the seed load. Leaving the last flush of the season to seed is what actually populates the bed.

Decide deliberately each year how many seed heads you want to leave. Two or three heads on one plant produce far more seed than you will ever sow. Everything beyond that is next year's weeding.

Mallow seed survives a compost pile at ordinary garden temperatures. Put seed heads and seeding stems in the bin, not the heap, or you will spread the colony to every bed you mulch.

Managing the volunteers you already have

Volunteers appear from early spring onward, usually in a dense scatter within two feet (60 cm) of where the parent stood, and often in the gravel and path edges nearby. They are worth thinning rather than eliminating: a self-sown seedling that has never been moved makes the best plant you can get.

The critical thing is to hoe early. A mallow seedling at the two-leaf stage comes out with a flick of a hoe. The same seedling four weeks later has an inch of taproot and needs a fork, and by midsummer it snaps off and regrows from the root.

1. Hoe at the seed-leaf stage Run a hoe through the volunteer patch on a dry day when the seedlings still show only their two heart-shaped seed leaves. They wilt and die on the surface within hours. This is the entire job if you do it on time.
2. Keep one or two, in the right places Mark the volunteers standing where you actually want a plant and hoe everything else. Keeping the well-placed ones gives you next year's plants for no work at all.
3. Move a volunteer only when tiny If you must relocate one, do it under two inches (5 cm) tall, lift it with a trowel-sized block of soil so the root tip is undisturbed, replant immediately and water in. Anything bigger will check badly and never catch up with a direct sowing.
4. Dig out established strays properly A volunteer you missed for a season has a taproot several inches long that regrows from any piece left behind. Loosen it with a fork and pull the whole root, rather than hoeing the top off repeatedly.

What to record about seed and volunteers

Seed saving is a year-to-year loop, and the notes are what close it. Which plant the seed came from matters, because you should be saving from the plant that flowered best and rusted least, not from whichever one you happened to reach first.

Record volunteer numbers as well. The count is a direct measure of how well your deadheading worked last season, and it is the only honest feedback you will get on it.