Raising gas bubbles as soon as you dig with a stick; Plants with a puny silhouette; Conical and spiral snails no longer burst during the day; Low, rotten, sometimes black roots.
Compacted or too old sol.
Slope the soil and suck the dust. Press the ground to remove gases. Clean filters 2 days later, then fertilize 1 week later. If the plants do not repel after 2 weeks, change the ground. By prevention: do not leave the same soil for more than 3 years.