Some plants not suitable hydroponics include root vegetables, large trees, and cacti. These plants need things that water based systems cannot provide. You can still grow almost anything else with great results in your setup.
I tried growing carrots in deep water culture once. The roots came out stunted and forked in all directions. They needed soil to push against as they grew. Without that pressure, my carrots never formed right.
Root vegetables like carrots, beets, and radishes need 8-12 inches (20-30 cm) of loose medium to grow into. Most hydroponic systems don't offer this depth. Your roots have nothing to shape them as they develop.
You will see hydroponic plant limitations with potatoes too. Tubers form when you bury stems in darkness. Standard setups expose everything to light. You can grow sweet potato greens but your tubers won't develop well.
Large trees and shrubs count as crops bad for hydroponics in most cases. They need stable anchoring that your water alone cannot provide. Their root systems grow massive and would outgrow any container within a year or two.
Cacti and succulents evolved for drought conditions. Their roots rot fast in your constant moisture. You would need to let the system dry out between waterings. This defeats the purpose of running hydroponics at all.
Corn takes up huge amounts of space for what it produces. Each stalk gives you maybe two ears at most. The space to yield ratio makes it a poor choice for your indoor setup. Grow corn in a garden if you want fresh ears.
What not to grow hydroponics also includes plants that need wind or insects to pollinate. Corn fits here since it relies on wind to move pollen. Indoors you would need to hand pollinate every single plant yourself.
Some growers do succeed with modified setups for these difficult crops. Deep container systems with loose media can grow your carrots. Potato towers with layers of growing medium work for tubers. These need special gear beyond standard hydroponics.
I focus my hydroponic space on leafy greens, herbs, tomatoes, and peppers now. These plants thrive in water based systems with fast growth and high yields. The return on your effort beats trying to force difficult crops to work.
If you really want root vegetables, try a garden bed alongside your hydroponic setup. You get the best of both worlds that way. Fast growing greens from hydroponics and root crops from your soil beds outside.
When I first started, I wasted months trying to grow things that don't work well in water. Now I pick crops that match my system. My harvests doubled once I stopped fighting against plant biology and worked with it instead.
You can grow almost anything in hydroponics with enough effort. But your time and money go further when you pick crops that match the system. Save the tricky plants for your outdoor garden and let your hydroponic setup shine with what it does best.
Read the full article: Hydroponic Nutrient Solutions: The Complete Guide
