Learn how to water your garden

Water rationally

It’s bringing the right amount of water at the right time. The right moment is before the substrate begins to dry out, in the cool period (rather) in the morning, before the plant shows signs of wilting (approaching without reaching the point of wilting).

How much to bring?

In theory, the amount of water supplied per plant or per m² should just cover what is called Evapotranspiration (ETP).
It is a theoretical figure calculated by meteorologists from several parameters, temperature, wind, light, wind, day length…

Successful irrigation is therefore calculated in mm of water (like rain), by adding the daily ETP since the last water supply, irrigation or rain.
NB: watering or rain of less than 4 mm should not be counted as an input, the loss by direct evaporation is almost total.
The unit of calculation is the mm of water, 1 mm of water is equivalent to 1 liter of water per m² which is really negligible.

An easy-to-do calculation method to assess the value of your watering with a hose. Take a 10 liter watering can and fill it with your hose and garden hose, timing precisely how long it takes. You get a time that represents 1 mm of water on one m² of garden.
All you have to do is calculate the watering time needed for an area by multiplying the number of mm needed X the area to be watered X the time to fill your watering can.
This calculation basis is the same for sprinkler, drip, hose or watering can irrigation.
if you do this calculation you will quickly realize that you are consuming a lot of water in a particularly inefficient way.

Efficient watering provides between 10 and 15 mm of water at each intervention to wet the substrate deeply enough.
In general the daily ETP varies in summer between 4.5 and 6.5 mm of water in summer.
It therefore clearly appears that a correct watering is enough to maintain a culture between 2 and 3 days without problem.
In addition, this technique makes it possible to limit the risk of disease of the collars.

The technical means:

· Sprinkling, whether or not connected to a programmer, is an interesting technique for a homogeneous surface such as a lawn for example. For programming, the calculation can be quite complicated if there are several types of sprinklers with different flow rates on the same irrigation line. · Sprinkling, whether or not connected to a programmer, is an interesting technique for a homogeneous surface such as a lawn for example. For programming, the calculation can be quite complicated if there are several types of sprinklers with different flow rates on the same irrigation line.

· The drip consists in installing a pipe with microdiffusers between the plants by calculating which surface a micro diffuser irrigates to position the pipe (microperforated or with added drippers).
Be careful, due to the thinness of the pipes and the orifices, very well filtered water is required.
· The garden hose fitted with a sprinkler head allows you to distribute the water well manually but strongly wets the foliage, to be avoided on sensitive foliage.
· Watering at the neck of the hose is very useful for evenly distributing the water at the foot of the plants. It is enough to first calibrate the flow rate of the pipe.
· Finally the watering can, although more tedious, is the most economical method of water and very easy to follow. It does not require a pressurized water network (public network or pump).
· Do not forget the Oyas which are porous terracotta jars that are buried and filled with water. This water stored below the soil surface gently percolates through the soil maintaining a certain relative humidity.
It requires an initial investment and is well suited to crops that require little water.
Be careful, don’t forget to cover the oya to prevent it from turning into a mosquito lodge.

In hot countries, water was traditionally provided by surface irrigation in a gravity system, very interesting in certain types of culture, but the gravity side is very limiting for its use.
In addition, this method causes accumulations of salinity in an area. Avoid with plants sensitive to salinity.

Ask all your questions during the gardening program on Sunday morning on France bleu Isère from 9 a.m. to 10 a.m. by calling 04 76 46 45 45.l