Calendula Care: Deadheading, Watering and Keeping Plants Compact

Deadheading is the whole job

Calendula is an annual with one purpose, which is to set seed and die. Every flower head left on the plant to ripen tells it that the job is done, and a plant carrying a dozen ripening seed heads stops making new buds within a fortnight. Take every head off as it fades and the plant simply cannot finish, so it keeps branching and flowering from early summer until frost stops it. There is no other job on this plant that comes close in effect.

Do it properly. Snapping the dead head off at the top of its stalk leaves a bare stick and the plant branches from lower down anyway, so cut or pinch the whole flower stem back to the first pair of good leaves below it. That produces two new shoots from that pair of leaves, each of which will carry a flower. Deadheading calendula correctly is therefore a way of building the plant, not just tidying it.

1. Go over the plant every two or three days A flower head takes about a week to open, fade and start setting seed. A pass every second or third day catches all of them and takes two minutes per plant.
2. Cut back to a pair of leaves Follow the flower stalk down to the first good pair of leaves on the branch and cut just above them. Two new shoots come from that point within a week.
3. Take the faded ones as well as the dead A head with drooping, papery petals is already setting seed. Do not wait for it to look obviously dead, because by then the signal has been sent.
4. Pick for the kitchen and it is the same job Every head cut at its peak for drying is a head that never sets seed. Harvesting and deadheading are the same operation on this plant.

Stop deadheading three or four weeks before you expect the first hard frost if you want the plant to self seed, or keep going to the end if you do not. That single choice decides whether the bed has volunteers next spring.

Grow it hard: no feed, full sun, ordinary soil

Calendula flowers best in soil that a gardener would think too thin for a vegetable. Fed with nitrogen or sown into a bed that has just had manure worked in, it makes big soft leaves, long weak internodes and comparatively few flowers, then falls apart in the first summer downpour. It also mildews far worse, because the soft growth and the crowding go together.

Give it six hours of direct sun and free draining ordinary ground, and do not feed it at all during the season. Part shade is tolerated, and in a hot climate afternoon shade actually extends the flowering, but deep shade gives a leaning plant with pale flowers held on long bare stems. If you only have rich ground, sow at the wider spacing and plan to cut back earlier than you otherwise would.

Water at the root, and only when it needs it

An established calendula finds most of its own water through a normal summer and only genuinely needs watering in a dry spell. Judge it in the morning: a plant that wilted in afternoon sun and recovered by evening was never short of water, while one still limp at first light has run out at the root. Watering in response to afternoon droop is how people end up with soft plants and root rot.

When you do water, soak the base properly, half a gallon (about 2 liters) per plant, rather than sprinkling daily. Keep the water off the foliage: calendula leaves hold water in their slight stickiness, and wet leaves in a crowded plant are exactly where the late season powdery mildew begins. Containers are the exception and need checking every day in hot weather, because a pot dries out from the top and calendula in a dry pot goes straight to seed.

1. Check at first light, not in the afternoon Afternoon wilting in full sun is normal and self correcting. Only a plant that is still flat in the morning has run dry.
2. Soak once rather than sprinkle daily One thorough watering every week to ten days in dry weather beats a daily splash, which keeps roots at the surface and weakens the plant.
3. Aim the can at the soil Use a can without a rose and water the base. Wet leaves in a crowded row are where mildew starts in the second half of the season.
4. Mulch once the plants are established An inch (2.5 cm) of straw or leaf mold holds moisture and keeps the lowest leaves off wet soil. Keep it back an inch from the stems.

Cut back hard at midseason and it starts again

Even a well deadheaded plant goes leggy after two months of flowering. The lower leaves yellow, the stems get bare and woody at the base, the flowers come smaller, and the first white mildew appears in the crowded middle. That is the moment to cut, not to nurse it along. Take the whole plant back by half, down to a point where you can see young shoots in the leaf joints, and it rebuilds and flowers again within three weeks.

Do not be timid about it. A quarter trim gets you a slightly shorter leggy plant. Take it down to eight or ten inches (20 to 25 cm), cut every stem to roughly the same height, and rake the cut material away rather than leaving it lying on the crown. Water the plant well the day before you cut and it regrows fast; cut in the middle of a drought and it sits bare and sulks for a month.

1. Cut on the signal, not on a date Yellowing lower leaves, bare stem bases, smaller flowers and the first mildew together are the signal. Usually seven or eight weeks after the first flower.
2. Halve the plant in one pass Take shears to it and cut every stem to eight to ten inches (20 to 25 cm). Uneven cutting gives uneven regrowth that flops.
3. Clear the debris off the crown Rake the cut stems away and compost them elsewhere. Left piled on the base they hold wet against the crown and rot it.
4. Water it in and wait three weeks A good soak after cutting brings the new shoots away quickly. Do not feed it, even now, or the regrowth will be soft.

In a long season you can do this twice. A plant cut in midsummer and again in early autumn flowers right through until the frost blackens it, which is far longer than most annuals in the same bed.

What to write down about the growing season

Three records make next year's calendula better. The interval from sowing to the first open flower, measured in days rather than dates, tells you how to stagger the sowings for continuous bloom. The date of the hard cut back and the date the second flush started tell you how late you can still cut and get flowers before frost. The date you stopped deadheading records the decision about self seeding.

Add a sketch of the bed with the position of every plant on it. Calendula seed falls straight down and the volunteers come up in a ring around the parent, so this year's planting plan is next spring's weeding map. Note which plants stayed compact and which went soft and flopped, together with what had been done to that ground the previous autumn, because the difference is almost always feed rather than the plant.