Marjoram

Light and exposure

Marjoram demands full sun, like all Mediterranean herbs. Give it the warmest and brightest spot you have, open to the midday sun, sheltered from wind, against a wall that holds the heat. It needs at least six hours of direct sun to develop that soft, sweet scent that sets it apart from oregano.

In shade it grows limply, stretches and loses its aroma. Under an often overcast sky, growing it in a pot is a real help: you follow the sun, move the plant close to a warm wall, and can easily bring it in as soon as the nights cool. That is in fact the growing method best suited to its tender nature anywhere winter brings frost.

Watering

Marjoram needs moderate watering, without excess. It likes soil that stays fresh at the surface during active summer growth, but it hates having its roots in water. Let the top few centimetres of soil dry between waterings, and water preferably in the morning, at the base, without wetting the foliage.

In a pot, where the substrate dries faster, watch closely in summer and water as soon as the surface is dry, without ever soaking it. A marjoram that gets too much water, especially in cool weather, develops collar rot. At the end of the season and for a plant you bring in for winter, cut watering back sharply: at rest and in the cool, it wants almost no water.

Soil and repotting

A light, loose and above all well-draining soil suits it perfectly. It does not demand rich earth: an over-fed substrate makes it grow soft leaves and reduces its scent. A little mature compost at planting is enough to support its growth.

In heavy, clayey soils, lighten with coarse sand and plant on a slight mound so the water runs off. In a pot, a mix of good potting soil and sand, over a drainage layer at the bottom, recreates its original conditions and limits the risk of rot, its main weak point wherever the climate is damp.

Temperature and humidity

This is where everything is decided, and it is what separates it from oregano. Marjoram is markedly more tender: it grows well between 18 and 25 degrees and already suffers when the nights turn cool. It is perennial in USDA zones 9 and 10 only, and does not survive the winter outdoors anywhere frost sets in.

In practice, two strategies. Either you treat it as an annual: sown in the warmth, put out only once the last frosts have passed and the nights hold above 10 degrees, harvested all summer, then left to finish with the first cold. Or you grow a plant in a pot that you bring in before the frosts to a bright, frost-free spot, a cool conservatory or a sunny windowsill, to restart it the following spring. Never count on it to come back on its own in the garden the way oregano does.

The exact threshold is worth knowing so as not to be caught out: marjoram takes a very light, brief frost without great damage, down to about -1 degree, but a few degrees lower and its foliage browns and wilts in a single night, a stage it almost never recovers from once the cold season has set in.

Pruning and upkeep

Pinch the stem tips regularly during the growing season. The plant branches, stays compact and bushy instead of bolting, and each pinch triggers new tender shoots to harvest. It is the same gesture as for basil, and it almost doubles production.

The main harvest is done before and during flowering, when the foliage is most fragrant: cut the stems fairly low to prompt regrowth. For a plant brought in for winter, cut it back after summer to give it a compact shape before its rest period in the cool, and remove dry or damaged stems.

Pests and diseases

Marjoram is little prone to disease when its conditions are met, sun and good drainage. Problems almost always come from moisture: collar and root rot threaten in soil that is too heavy or too watered, especially under a damp summer and on plants brought in for the cold season and over-watered while at rest.

Too much water and a lack of air also favour powdery mildew, that white felt on the leaves. The defence is cultural: space the plants, give air, water at the base in the morning and let it dry between waterings. A few aphids may appear on the young shoots in warm weather, without real seriousness.

Propagation

Sowing is the most common method. Sow under cover, warm between 18 and 20 degrees, from March or April, on the surface as the fine seeds need light to germinate. Emergence is a little slow and capricious, allow two to three weeks, and keep the sowing nice and warm. Only transplant and put the plants out after mid-May.

Marjoram also takes easily from cuttings in summer: take a non-flowering stem of ten centimetres, remove the lower leaves and place it in water or in a light, moist substrate until it roots. It is a good way to keep a plant from one year to the next by overwintering the cutting in a frost-free spot.

Month-by-month care calendar

Green Hub tips

• Never confuse marjoram and oregano. Oregano (Origanum vulgare) stays outdoors and comes back every spring; marjoram (Origanum majorana) is tender and does not survive a freezing winter outdoors.
• Two strategies for winter: either grow it as an annual and resow each year, or bring a pot into a bright, frost-free spot, watered to the minimum.
• Put it out only after mid-May. Like basil, a mild April is a trap, the late frosts kill it.
• Harvest before and during flowering: that is when the foliage is most fragrant, before the plant exhausts itself making seeds.
• Pinch the stem tips often for a bushy, compact plant. Each pinch triggers tender shoots and almost doubles the harvest.