Rosemary (Salvia rosmarinus, formerly Rosmarinus officinalis) belongs to the family of Lamiaceae. It does not exceed 2 meters in height. This evergreen shrub therefore finds its place in all gardens, even the smallest. In Provence, it is nicknamed incense burner because its leaves have a camphoric smell very marked. Its flowers develop in clusters and can be, depending on the variety, blue, purple or white. As for the fruit of rosemary, it is a brownish tetrakene. Let’s find out what are the best conditions for growing a rosemary whose aromatic branches are essential in cooking but also widely used in herbal medicine and perfumery.
Plant a rosemary
To enjoy the scent of rosemary that evokes Mediterranean regions, just plant one in the garden or in a pot. Planting rosemary does not pose any particular difficulty and can therefore be done by novice gardeners.
Planting rosemary in the ground
- Dig a hole about fifty centimeters deep and wide so that the roots are not cramped.
- Improve the quality of the soil if it is too compact. For example, it can be mixed with two large shovelfuls of coarse sand or even with gravel when necessary.
- Place a bed of sand at the bottom of the hole.
- Take the rosemary root out of its container.
- Untangle the roots if necessary, without damaging them.
- Install the shrub in the planting hole.
- Recap and pack the soil around the foot.
- Water copiously.
If you want to plant several rosemary in the ground, you must take care to separate them from each other by about 55 cm if it is an upright variety, and it is necessary to reserve a good square meter. by creeping rosemary.
Planting rosemary in a pot
This shrub also thrives in a tank with drilled bottom and large enough that its roots have enough room. We then install the rosemary in a mixture of 30% sand and 70% potting soil. Once the planting is finished, it is advisable to water generously then to place the potted rosemary in an area located in full sun and sheltered from the prevailing winds.
Growing a rosemary
Rosemary is planted in autumn in the southernmost regions, and preferably in spring in less clement climates. It prefers to be installed in a slightly acidic soil, well drained, and can be quite acclimatized if the soil is moderately calcareous. We can therefore appreciate its low requirement in terms of soil quality. Above all, we must ensure that the earth can never be saturated with water. As for the preferred exposure of this southern shrub, the full sun is required.
Caring for a rosemary
Rosemary is undoubtedly one of the easiest plants to grow.
This shrub native to the Mediterranean Basin fears humidity in winter which can be much more detrimental to it than dry cold if it remains moderate because rosemary does not support extreme cold. It is in any case essential that its soil is drained, and even under a great heat, watering is not necessary because rosemary has very low water requirements that the rains are sufficient to meet.
Apart from watering after planting the shrub, it should only be watered afterwards to prevent its leaves from wilting, even turning brown or falling, which can only happen in case of extreme and prolonged drought.
At the most, we can cut back moderately a rosemary that is a few years old if it has grown a little too high or even if he starts to lose hair at the base. Otherwise, it does not necessarily need regular pruning since the harvest is enough to shorten the branches.
It may be useful to add nitrogen after harvesting. In general, rosemary thrives particularly well in a soil rich enough to meet its needs in potassium, magnesium, nitrogen, but also sulfur and phosphorus. However, many gardeners have had very beautiful rosemary for years, without regularly fertilizing the soil.
Protect from the cold
If temperatures are likely to drop below -8 ° C, it is strongly recommended to protect a young rosemary with a wintering veil. Specimens grown in pots can also be covered and then installed against a wall that enjoys good sunlight.
Parasites and diseases
Rosemary is not particularly prone to parasites. At most we can see some mites on the back of its leaves in a particularly dry and hot environment, which can cause small yellow dots on the foliage. A few sprays of rapeseed oil or even the use of a pyrethrum-based product (preferably without chemical ingredients) is generally sufficient to eradicate the parasites.
On the other hand, it can be affected by a fungal disease, the botrytis or gray rot, due to the presence of a pathogenic fungus : Botrytis cinerea. This problem strikes rosemary especially in case of excessive humidity, especially in a cold region. This fungus is said to be polyphagous because it feeds on the living tissues of rosemary, and many other plants for that matter. The signs that should alert are the browning partial or total of the branches which gradually take the shape of a stick due to the inexorable curvature of their end.
For treating rosemary botrytis, it is advisable to spray it generously with a horsetail decoction. Sick branches must be removed and then burned. It is noted that this disease can also appear on rosemary which is planted too close to each other. Sufficient space between the feet allows the air to circulate better, which is why this should be taken into account when planting.
Harvest the rosemary
The picking should remain moderate in very young plants one year old, and becomes more and more important over the years. The ideal is to harvest as needed, when the weather is hot and it is not raining. Note, however, that rosemary is harvested throughout the year except on frost days whenever possible.
Harvesting therefore makes it possible to prune branch segments, which favors their branching. In this way, new aromatic leaves will develop. A sharp pruning shears is sufficient for a clean pruning.
The freshly harvested rosemary can be kept for three days at room temperature, in a vase filled with water, and for one week in the vegetable drawer of the refrigerator, provided that care has been taken to wrap it beforehand in a damp paper towel. To freeze it, it is necessary to chop the rosemary leaves as soon as they return from the garden so that they keep their aroma, and to distribute them either in very small freezer bags or in ice cube trays. This will then allow you to take only the desired amount.
Rosemary can keep for several months after having sun dried for a few hours. It is then necessary to form bouquets and then store them in paper bags that can be hung in the cellar or in any type of cool, dry and ventilated room. Finally, you should also know that rosemary flowers are edible. Their flavor is sweeter than that of the leaves because they contain less essential oil. They are preferably eaten raw because they have more taste as well, but they can also be infused. They flavor meats, vegetables, fruits, dairy desserts and ice cream.