Spinach plants experience different kinds of problems, and how their leaves look gives clues as to what is going on.
Leaf burn due to excessive sunlight, high temperatures, and improper watering. Spinach prefers cooler temperatures and can suffer if exposed to intense heat and direct sunlight, which can cause the leaves to scorch and turn brown or yellow.
To prevent this, spinach should be planted in a location that receives partial shade, particularly during the hottest part of the day, or shading the spinach in the garden bed with a shade cloth. Additionally, using mulch can help keep the soil temperature cooler and retain moisture, providing a more stable environment for the plants.
Inconsistent watering: spinach like regularly moist, but not waterlogged, soil. Both under-watering and over-watering can stress the plant. Under-watering can lead to dry soil conditions, causing the leaves to dry out and burn, while over-watering can result in poor root health and fungal diseases, which also contribute to leaf damage.
For optimal moisture levels, water spinach plants deeply and consistently, aiming to keep the soil evenly moist. Drip irrigation systems or soaker hoses are particularly effective in providing steady moisture while minimizing the risk of over-watering. Proper soil drainage is crucial to prevent water from pooling around the roots.
Other culprits could be overcrowding (give the plants room to breathe), nutritional deficiency in the soil (although unlikely), insect problems (again, unlikely as spinach doesn't usually have problems with insects), disease (cucumber mosaic virus will show yellow spots on the veins of the leaves - if present yank the plants out of the ground as there is no cure for this virus).
Read this helpful article (which includes a great video) for signs your spinach is preparing to bolt (the end of it's lifecycle). Credit: Gardenary