Yes. Strawberries live too long for a single fill, so topping up is part of growing them. The rule is to refill part way and never back to the brim.
Why Lettuce Growers Say Never Refill
The Kratky method was designed around quick crops that finish on one fill. For those, refilling is unnecessary and risky. Strawberries fruit for months and will empty any container several times over, so the advice has to change.
When to Top Up
Top up when the level has fallen to roughly a third of the container, or sooner if the lowest roots are close to being out of the solution. Do not wait until it is nearly dry. A fruiting plant can finish the last of it in a day.
How Far to Fill
Fill to about half or two-thirds, leaving at least a couple of inches of air under the net cups. The roots that have grown in that air gap are adapted to air. Submerge them and they suffocate, which is how a well-meant refill kills a healthy plant.
What to Fill It With
- With an EC meter: measure first. If the reading is high, add plain water. If it is in range or low, add nutrient solution.
- Without a meter: alternate plain water and half-strength solution.
- Check the pH after every top-up.
When to Start Fresh
Every few weeks, empty the container and refill with new solution, again leaving the air gap. Topping up corrects the strength but not the balance, since the plant uses some nutrients faster than others. A full change resets everything. Do it sooner if the solution is cloudy, green or smells.
Related guide: How the Kratky method works with strawberries.
