pH for Kratky Strawberries

Nutrients dissolve and stay available to roots only within a certain pH range. Outside it, a nutrient can be present in the solution and still be out of reach of the plant. Iron is the usual first casualty when pH climbs too high, which shows as yellowing between the veins of the newest leaves.

This is why adding more nutrients rarely fixes a plant that looks hungry. Check the pH first.

• Liquid test kits use a few drops of indicator in a small sample and a color chart. They are cheap, reliable and need no calibration.
• pH pens give a number on a screen. They are faster and more precise, but need regular calibration and proper storage to stay accurate.

Always test after the nutrients are mixed in, since nutrients change the pH of the water.

1. Add a very small amount of pH down or pH up. A few drops goes a long way in a small container.
2. Stir thoroughly.
3. Wait a few minutes and test again.
4. Repeat until the reading sits between 5.5 and 6.5. Most growers aim near 6.0.

pH adjusters are strong acids and bases. Follow the label, add them to the water and never mix the two together.

pH does not stay where you set it. As the plant feeds, the pH of the solution usually creeps upward, and hard tap water pushes it up further. In a Kratky container nothing is circulating or being replaced, so the drift builds up.

Test whenever you top up, and at least once a week while the plant is fruiting. If the pH keeps running away, replacing the whole solution is quicker than chasing it with adjuster.

• Why Your Kratky Solution's pH Keeps Rising
• pH Drops vs pH Pen: Which Is Better for a Small Kratky Setup?