I planted 4 dwarf bean plants from seeds. It's been three weeks and they were doing pretty well. Recently I've noticed that the tips of the leaves are drying out and curling inwards, or tearing at the edges. I have been watering these plants but I'm conscious of overwatering. About two days ago I gave the plants some diluted hydroponic fertilizer. However the problem was present before I put the fertilizer on the plants. I also examined the leaves and couldn't see any pests. The climate where I am is subtropical humid. I would love to save my bean plants and any help will be so appreciated!
It certainly sounds like a water problem - too much / too little. Firstly, you need to check the moisture content and the easiest way to do this is with your finger, if the soil feels damp then don't water. If the soil is too wet is can lead to fungal disease of the roots and preventing the roots taking up water. The other common problem stopping the roots taking up water is the curl grub. Curl grubs are fat white grubs in the shape of a letter C hence their name. They love new roots and munch through all the seedlings roots very quickly preventing the uptake of water. A classic sign of these pests your plant always looks thirsty. Unfortunately once the seedling's roots have been affected they will not recover and need to be taken out and the seedlings replace