Watering the vegetable garden

Water is a rare and essential commodity in the vegetable garden. Without it, plants cannot grow, but it is important to recognize the needs of each plant depending on the species, the type of soil, and the climatic conditions. SPECIES There is a classification of plants according to their water needs: • Camel plants include plants that are very resistant to aridity and can grow even in exceptional drought. Example: Helichrysum, ice plant, thyme, rosemary, beans, garlic, onions, or shallots. • Sober plants include plants that regularly need water but in small quantities. They tolerate slight water stress. Example: Basil, borage, tomatoes. • Demanding plants include plants that need moist soil, but not soggy soil. Example: A large majority of root vegetables, corn, lettuce, zucchini. This classification was also created based on the root hair: the larger and longer the roots, the more water they will be able to draw from the soil (example: tomatoes). Since less water is present on the surface of the soil due to evaporation, any plant with a less developed root system will need more frequent watering (example: lettuce). SOIL TYPE The characteristics of the cultivated soil are essential to take into account when adjusting water needs. There are 3 types of soil: Sandy soil: very draining, it retains very little water. In summer, it heats up quickly, causing the water to evaporate. Watering must therefore be frequent. Clay soil: retains water, it dries out very slowly. It is asphyxiating for the root system and can cause plants to rot. In summer, it becomes very compact and hard to handle. Beware of overwatering. • Silty soil: It is between the other two types of soil. It is a more compact soil than sand but less so than clay. Silty soil is well-draining but retains enough water and minerals to nourish plants. It is necessary to check the soil moisture before watering. If you do not know the type of your soil, there is a simple and effective method. To do this, take a little soil in your hand. Moisten it and knead it for a few moments. If the mass of soil remains compact, it is clay soil. If the soil is malleable but the mass breaks, it is silty soil. On the other hand, if the soil feels rough like sand and does not stay compact, your soil is sandy. CLIMATIC CONDITIONS The weather will greatly influence water needs and can vary the frequency of watering. 3 factors: • The wind dries out the plants and accelerates the evaporation process of the water contained in the cultivated soil. • The sun: be careful with plants in full sun where the risk of the soil drying out and leaf burns is high. The need for water is less important when the plants are installed in a shady corner. • Temperature: Heat also accentuates the process of evapotranspiration. This is the evaporation of water contained in the tissues of the plant in addition to that contained in the soil. When the plant loses water from its cells through this phenomenon, it is said to be "transpiring". This mechanism is vital for the plant. When these 3 factors are combined, watering must be copious and regular because they can evaporate up to 10 liters of water per day and per m². To limit evapotranspiration, it is advisable to mulch the crops. Composed of either straw, grass clippings or dead leaves, mulch will protect the top layer of the soil and limit the evaporation of water from the soil. This will allow for less frequent watering, promote organic life and nourish the soil by decomposing. When and how to water? Watering should be applied to the base of the plant and not on the foliage to limit fruit rot or diseases such as powdery mildew. We recommend watering early in the morning whenever possible so that the plant can draw water before temperatures rise. It is also possible to water in the evening during periods of high heat, when the soil has used up its water reserves during the day. Watering adds a certain humidity to the air, which is responsible for many diseases when it is too high. At dawn, the first rays of the sun will gently dry and warm the air. Watering at the end of the day should be avoided at the end of the season when nights become cooler. It is important not to water in full sun, as the risk of burns is high and the water could evaporate before the plant has time to benefit from it. A localized watering system (such as drip irrigation or oya) has the advantage of being able to control the water supply both in quantity and frequency. How much? On average, for an unmulched vegetable garden below 25°C, you need about 20 liters of water/m² every 3 days when the plants are fruiting in loamy soil. For a mulched vegetable garden below 30°C, you need about 20 liters of water/m² every 6 days in loamy soil. Please note that these data are averages and may vary depending on climatic conditions and the species grown. Below is a graph showing the importance of mulching on watering frequency: What equipment should be used to water crops? A watering can The bulb directed upwards or downwards allows for two types of rain watering, while the neck will be used to water at the base of some plants that do not like having wet foliage. A drip system Even though it is expensive equipment, the advantages are considerable: better seedling emergence, fewer weeds between the rows, more targeted watering to avoid diseases, and less evaporation. A sprinkler system This solution is for gardeners with a large garden. Sprinkling can be essential to recover a plot that is too dry in summer or should be reserved for certain vegetables that prefer to receive water on the foliage rather than at the feet (winter radishes, lettuces, Asian cabbages, etc.). Often beneficial, its use nevertheless requires some precautions to avoid wetting the foliage of plants sensitive to fungal diseases located nearby. It is also a very water-consuming system that should not be used in the middle of the day or in the heart of summer. How to evacuate too much water in the vegetable garden? Soil that is flooded for several consecutive days is hydromorphic: aerobic life therefore no longer occurs and the microorganisms essential for good soil activity disappear. It will be wise to carefully observe the slopes of the land and any natural basins that could turn into real ponds in winter. A few shallow drainage ditches at the end of the rows, a judiciously placed basin and a few other small common sense jobs are often enough and can prevent many disasters.