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Basil (Ocimum basilicum) with its strong green leaves and unmistakable aroma has become an integral part of Mediterranean cuisine. The royal herb, which probably originated in India, has been cultivated in Europe since the 12th century. In order for the popular kitchen herb to thrive, however, it needs a suitable location and good care. If the plant gets brown leaves, it often indicates location or care errors.
Brown leaves on basil
Fresh basil - botanically also known as Ocimum basilicum - is indispensable in both Mediterranean and Asian cuisine. No wonder, then, that the kitchen herb, which has been popular for centuries, has been steadily increasing in sales for several years. However, if the amateur chef carries home the potty he has just bought from the supermarket or even from the expensive gardening store, the rude awakening usually occurs after only a few days on the kitchen bench: the basil plant develops yellow or brown leaves, begins to wilt and finally dies.
Growth accelerators cause stressed plants
The reason for this phenomenon are the industrial growth conditions for both the cheap and the expensive basil pots, which are grown within a very short time thanks to optimized seed selection, targeted use of light and perfect location and soil conditions. However, the plantlets in question look perfect at the time, but have not had a chance to grow into vigorous adult plants. In addition, the sensitive plants have often suffered drastically during transport.
So that the basil pot from the supermarket has a chance of surviving in your home, you should heed the following measures:
- do not remove the protective plastic film immediately
- instead, only remove about one centimeter of the foil every day
- Repot basil in fresh, nutrient-rich substrate
- Distribute the plants, which are usually too close together, over several planters
- bright and warm
- cultivate outdoors if possible
- no draft
- slowly getting used to the new location (caution, sunburn!)
- do not overwater, do not let dry out
- never water from above or spray plant
Ocimum basilicum is an extremely sensitive little plant, which quickly reacts to changes in the environment and, above all, to incorrect care and an unsuitable location with leaf discoloration - regardless of whether you brought it home from the supermarket in a pot or grew it yourself from seed. Brown leaves or leaf spots are usually a sign of care mistakes, which can be turned off. In the following overview we will explain the possible causes of the brown spots and how you can quickly get your ailing basil plant back in shape.
Basil is not suitable for a window sill culture. The warmth-loving plant feels most comfortable outside in the fresh air, where it prefers a spot in full sun on the balcony or in the garden. Plant the herb in a place where there is at least sun six hours a day receives.
However, do not plant or place the basil plant directly in the blazing sun, but slowly get used to it over a period of several days. A sudden move from the artificially lit supermarket to the herb bed in full sun often leads to brown spots on the leaves - in this case it is sunburn. Shade the affected plant over the midday hours and cut off the stained parts of the plant.
Basically, basil plants should be brought into the house at temperatures below 12 °C, because as originally tropical plants they cannot tolerate such coolness despite the centuries-long culture in Central Europe. On the other hand, warm temperatures from 20 °C are optimal, preferably more. But be careful: Basil bushes do not like drafts or locations that accumulate heat, for example in front of a bright south-facing wall. An airy location that also offers protection from rain is ideal.
tip: Cultivate the herb together with tomato bushes planted under cover, because the two types complement each other perfectly: the essential oils of the herb keep pests away from the tomato plants, while the basil itself benefits from the cover.
In contrast to most other herbs from the Mediterranean region, Ocimum basilicum is an extremely heavy consumer, which should be converted to a suitable substrate as soon as possible after purchase. The plant feels most comfortable in a potting soil that has the following properties:
- rich in nutrients, the highest possible proportion of humus and compost
- no peat
- deep, well drained (if necessary loosen up with perlite, expanded clay or sand)
- pH between 6.5 and 7.5
If the basil is in soil that is too light, you should either change the substrate, upgrade it with high-quality compost or supply the plant with herbal fertilizer more often.
Heavy, wet soil or lack of drainage
Heavy, loamy soil is only suitable for growing basil after a massive improvement with compost and sand, and you should definitely install effective drainage here. To do this, fill the bottom of the planting hole with a layer of gravel several centimeters thick. Drainage is also essential in the pot so that excess water can drain away quickly. Too much moisture initially leads to leaf spots, later the roots rot and the whole plant dies. In the event of excessive watering or waterlogging, you should repot the plant in fresh substrate and cut back both the roots and the above-ground shoots vigorously.
Since basil does not tolerate drought or excessive moisture, it quickly develops brown leaves both when there is too much moisture and when the substrate is dry. So that the plant is fit again quickly, you should do the following golden casting rules note:
- use lukewarm water, never cold
- Rainwater or well-stale tap water
- Basil is sensitive to lime
- Water early in the morning if possible, not in the evening
- with evening watering, the leaves dry off slowly
- never water from above, only directly onto the roots
- Never spray the plant
Especially when the basil leaves get wet, they discolor. For this reason, any moisture should be kept away from the foliage - this also applies to rainwater.
diseases and pests
In addition to the care mistakes listed, certain diseases and pests also lead to brown leaves and leaf spots:
- Wilt or stem rot (caused by the fungus Fusarium oxysporum)
- leaf spot disease
- Leaf sap sucking pests such as aphids and thrips
When fighting fungal diseases, it is important to cut out infected parts of the plant as quickly as possible. Other common household remedies such as horsetail decoction and other liquids should not be used, however, as the plants are also sensitive to them. Instead, dust them with dry charcoal or bedrock powder. Alternatively, neem or neem seeds worked into the plant substrate also help. You can also use these remedies in the event of a pest infestation, and the targeted use of beneficial insects, such as predatory mites or ladybugs, often helps.