How to prevent bitter-tasting spinach?

To begin with, when we talk about preventing bitter spinach we first need to understand what triggers heat stress. When the temperatures get above 70° F, the plant starts to produce excess oxalic acid, which is the explanation for bitterness. I try to get that gardeners harvest before 9 AM each summer morning, while they still have the cool of the morning to their advantage. After one client harvested in the middle of the day and reduced the bitterness by 60% by switching to harvesting early mornings.

Soil management affects flavor profile. My 1-inch compost topped layer minimizes the bitterness by keeping the root zone temperature stable. Test the pH monthly- I have found that when the pH is at 6.8 for spinach, the magnesium absorption is approximately 30% higher to counteract oxalic acid. As referenced in "Garden"; there is a gardener in Vermont who had persistent bitterness in spinach until he used dolomite lime with the soil mix to keep the pH stable and not acidic.

Watering methods are important! Drip irrigation allows for foliage to dry while moisture is maintained in the soil. Overhead sprinklers, in addition to wetting the soil, spray fungal spores onto plants, increasing bitterness. I install soaker hoses 2 inches deep so plants receive consistent hydration and their leaves never get wet. Drought-stressed plants will begin producing harsher flavors approximately 48 hours after water is depleted.

Pests heighten bitter flavors. Leaf miners, like caterpillars, cause plants to produce defensive chemicals that change flavor. Use neem oil weekly to reduce infestations; one study found treated plants had 40% less oxalic acid. Plant companion crops near garlic to repel aphids that stress plants.

Read the full article: How to Grow Spinach: 7 Essential Steps for Success