by Everyone, even a novice gardener, knows that the natural cycle of development and reproduction of any higher plant includes flowering, the formation of an ovary in place of the pollinated flower, and then fruits with seeds. In most cases, vegetable and berry crops are grown specifically for the sake of fruits.
For example, we eat tomatoes, zucchini, corn, strawberries, watermelons, cucumbers, currants, beans, etc. with pleasure. These are all fruits.
However, some garden plants are grown for their other “parts” – large above-ground leaves (single or gathered in a head) or underground juicy root vegetables. The former include all kinds of lettuce, spinach and other leafy greens, onions, different types of cabbage (for example, Chinese cabbage); the latter include radishes, beets, horseradish, carrots, daikon, celery…
And when such plants begin to bloom profusely, the gardener is not happy. The fact is that the flower-bearing arrow (it is because of it that this process is called “bolting” or “coming out into a bolt”), developing, blooming and forming ovaries, actively “takes away” from the ripening vegetable useful substances and energy, which it would direct to the “production” of edible parts. As a result, instead of large leaves and juicy root crops, we get them small, withered, dried out, with a changed taste and texture – that is, lush flowering and … a poor-quality harvest.
Why can plants in a garden bed bolt and how to prevent this situation? Let’s look at the example of radishes.
Why does radish bolt?
“Responsible” for bolting (i.e. accelerated release of the flower stalk) are phytohormones of the gibberellin family, the so-called flowering stimulants, which provoke generative development, i.e. accelerate reproduction, but not vegetation. And they can begin to act actively due to several factors, including changes in the length of daylight hours, the prevalence of high or low temperatures at certain stages of the plant’s growth cycle, and the presence of stress, such as a lack of water or minerals.
In simple terms, there may be several reasons for a plant to shoot up quickly – let’s look at the most common ones.
Firstly, it is untimely sowing. In the case of bolting crops, we are talking about the danger of recurrent frosts or unheated soil, and the length of daylight.
In the first case, if the sowing is done too early, the plants will experience cold stress already at the sowing and germination stage, and as a result of the stress, they will try to multiply quickly and produce seeds in order to survive in extreme conditions – that is, they will produce flower stalks faster.
If we talk about lighting, radish is a short-day crop. Ideally, such plants should be in the light for 10-12 hours. With excessive lighting, if the daylight lasts at least 13-14 hours and the air temperature reaches 25°C (and radish does not like heat and experiences stress), instead of a root crop, you will again most likely get an arrow. This is especially true for late-season plants, which do not have time to form a full-fledged underground part before the natural lengthening of daylight and the onset of heat.
Another reason for radish bolting is dense plantings. If the plants are cramped and uncomfortable in the garden bed, they have to “fight for resources”, they will also “strive” to bloom faster and give seeds instead of forming high-quality root crops.
Low humidity during the growing season (especially in combination with high temperatures) is also stress for the plant, and can also cause a similar situation, bolting. And for root crops, like the same radish, there is also coarsening, overdrying and bitterness of the underground part.
How to avoid radish bolting
What to do to get not a lush “bouquet” in the garden, but the long-awaited root crops and leaves? Follow some simple rules when cultivating such plants.
Firstly, select varieties that are not prone to, resistant to, bolting – these have been bred for all crops that are prone to this problem.
For radishes, these are primarily early varieties and hybrids – 16 days, 18 days, Double F1, White Breakfast, Deca, Zarya, Poker, Carmen, French Breakfast, Heat, Quarta, Rondar F1, Early Red, Champion, Rhodes, Celeste F1. If you want to get its root crops all year round and several times a season, and not just in the spring, choose varieties and hybrids marked “for continuous cultivation”, which are also not prone to bolting – for example, Würzburg 59, Gloriet F1, Hussar, Jolie, Duro, Ramtoush…
Secondly, choose high-quality seeds and observe the sowing dates of crops so as not to expose them to either temperature or light stress. Thus, radishes can be sown in greenhouses as early as March, and in open ground – in April (in regions with an unstable climate and the likelihood of recurrent frosts, the bed should be covered with spunbond at night).
If you are late with the timing (it is already May) or you have chosen late varieties of radish, you will have to cover the plants in the bed with dark non-woven material so that they are in the light for no more than 10 hours a day. Such partial shading will contribute to the formation of denser and juicier root crops.
Thirdly, take proper care of the seedlings. First of all, do not allow the plantings to become too dense, which we have already mentioned. When sowing, radish seeds are distributed evenly over the surface of the bed, at a distance of 3-4 cm between plants in a row and about 10 cm between rows. If you have difficulty handling small seeds, choose larger pelleted ones or be prepared to thin out the seedlings thoroughly as soon as the first pair of true leaves appear on the plants.
Do not forget about the plants during the growing season. So, you already know that radishes prefer cool weather and plenty of water, the soil in the garden bed with them should always be moderately moist. If you grow the crop at home on the windowsill, place the containers with crops away from the radiators and do not allow the soil to dry out; if you grow radishes in beds, follow the watering regime and norm, after watering, be sure to loosen the soil, and also ventilate greenhouses and hotbeds so that excessively high humidity and heat do not ruin the plants.
Let’s summarize. If some negative nuances arise during the cultivation of plants (low humidity against the background of heat, untimely sowing, recurrent frosts, lack of moisture and nutrition, dense plantings, etc.), radishes, like some other vegetables prone to flowering, can go into bolting. To prevent this from happening, it is important to understand the technology of the process, correctly select varieties for certain conditions and carefully follow simple agricultural technology for growing crops.
