Caring for Cumin: Weeding, Watering and Keeping the Plants Off Wet Soil

The plant you are looking after

A cumin plant is small and slight. It reaches eight to twelve inches (20 to 30 cm), branches from near the base into thin wiry stems, and carries finely divided thread-like leaves that give almost no shade. It flowers about six to eight weeks after sowing, in small white or pale pink umbels only an inch (2.5 cm) or so across, and the seed fills and ripens over the following four to six weeks. Nothing about it is robust, and it never forms a canopy that suppresses anything.

That slightness governs everything you do for it. It will not shade out a weed, it will not stand up to a heavy watering can, and it will not carry itself upright once the seed heads gain weight. Care for cumin is mostly about removing competition and keeping the plant dry at the right end of the season, not about feeding or training it.

It also means the crop from one plant is small. A row three feet (90 cm) long, well grown, yields a jar of seed rather than a bagful. Plan the area accordingly if you actually cook with cumin, and grow a block of several short rows rather than one thin line, which is easier to weed and lets the plants lean on each other as they fill.

Resist the urge to feed. Cumin on rich ground or a nitrogen feed makes lush soft growth, flowers later, ripens later, and is far more prone to mildew and to collapsing flat in a summer storm. Ordinary garden soil that grew a hungry crop last season suits it well.

Water through growth, then stop

Cumin needs steady moisture from emergence through to the end of flowering, then dryness while the seed ripens. Those two halves want opposite handling and the changeover is the single most important decision of the season. Watering into the ripening period keeps the seed green, encourages mold in the umbels and can cost you the entire crop even in a good summer.

During the growing half, water deeply and infrequently rather than lightly and often. Once or twice a week in a dry spell, enough to wet the soil four to six inches (10 to 15 cm) down, suits a plant with a taproot and encourages it to root deeply. Water at the base in the morning and keep it off the foliage, because the fine leaves hold droplets and stay damp for hours, which is how mildew starts.

Stop watering once the first umbels have finished flowering and the small green seeds are visible. From that point the plant is living on what the soil holds, and that is what you want. If your climate delivers rain during the ripening weeks, that is the point at which you cover the plants or cut them early and finish them under shelter, as covered in the harvest guide.

Keeping the plants off wet ground

As the seed fills, the thin stems bend under the weight and the plant sprawls outward until the ripening umbels are resting on the soil. On dry ground that is untidy but harmless. On soil that is damp after rain or dew it is where a crop rots, because an umbel lying on wet earth stays wet all night and molds from the inside where you cannot see it.

The cheap answer is a shallow mulch of straw, grit or coarse sand laid along the rows once the plants are four to six inches (10 to 15 cm) tall and the last weeding is done. It keeps the seed heads off bare soil, holds moisture during the growing half, and keeps splash off the lower leaves. Do not mulch earlier than that, because it makes the fiddly early weeding harder and keeps the soil cooler than cumin wants.

For a block planting, twiggy sticks pushed in around the edges or a low grid of string at four inches (10 cm) does a better job than staking individual plants, which are far too slight to tie. The aim is not to hold them upright, only to stop the outer plants from folding flat onto the path where they will be trodden on and where the heads will sit in mud.

1. Finish the weeding before you mulch Hand weed within the rows and hoe shallowly between them one last time when the plants are about four inches (10 cm) tall. After mulching it is much harder to get at weeds without disturbing the crop.
2. Lay a thin dry mulch along the rows An inch (2.5 cm) of straw, grit or coarse sand under the plants, kept clear of the stems themselves so the crowns stay dry and airy.
3. Edge the block with twiggy supports Push short twigs or run string at four inches (10 cm) around the outside so the outer plants lean inward instead of collapsing onto the path.
4. Switch to base watering at flowering Once the first umbels open, water only at soil level and only in the morning. Wet foliage overnight during flowering is the usual start of a mildew problem.
5. Cut the water when the seed shows As soon as small green seeds are visible in the first umbels, stop watering entirely and leave the plants to ripen on stored soil moisture.

What to record during the season

Record the date of first flower. That single date, set against your sowing date, tells you how many days your conditions took to bring the crop to flowering, and it lets you count forward four to six weeks to see whether ripening will land before your weather turns. If the flowering date is already late, you know in advance that the year is unlikely to work, and you can cover the bed or plan to finish the heads indoors rather than being surprised.

Note the position of the row and what grew there before, since cumin shares soil-borne wilt problems with other plants in its family and wants three or four years between crops of carrot, parsley, coriander, dill or fennel in the same ground. A rough sketch of the bed each year is enough, and it is the only way to keep that rotation honest.

Finally, write down how much watering you actually did and when you stopped. In a marginal climate the temptation is always to keep watering a crop that looks small, and a note from a previous season saying that you stopped in the third week of the ripening period and still got clean seed is the most persuasive argument against doing it again.