When Is The Best Time To Water Most Plants (mainly Tomatoes) With Regards To Soil Moisture?

Question

We have raised bed (4×12 feet x 18 inches tall) on top of grass with layer of stone then filter fabric then compost/soil. I use a hydrometer to measure the moisture and the top layer (1-2 in) is generally “dry” (2-4) but beyond that it remains consistently 4-7 (moist) even with minimal watering. Is this ok for root development? Don’t want to overwater and contribute to root rot but it seems like drainage issue (very bottom of raised bed registers as wet (7-9) with minimal watering). Area gets around 8-10 hours sunlight. Picture of hydrometer attached. Picture of plant attached – slight yellowing at bottom.

Answer 1

I don't think the soil should be staying that moist at that level. It sounds like your bed may not be draining well. If you see signs that your plants' roots are suffering, you'll know for sure they are staying too wet. The soil should be allowed to become almost dry before you water again.

I'm wondering if the filter fabric is the cause. Unless the compost/soil is heavy. You might consider slipping out the filter fabric if possible. You can add perlite to the soil if it is heavy.

https://www.gardeningknowhow.com/edible/vegetables/tomato/watering-tomato-plants.htm