Using Steel Greenhouse is not ideal it would only create some trouble, it is very difficult for those tiny hands to control the hose.
Your child will need the basic children's gardening tools in order to get started.
He should have a hoe, a rake, a spade, something to measure with, kid-sized gloves, and a watering can.
There are many websites which offer great tips for working with child gardeners as well as lines of tools built just right for children ages 5-8.
You'll be amazed at how sturdy these tools are with their forged metal heads and hardwood handles. You'll appreciate that these tools were made to last.
A watering can must absolutely be the right size in order for your child to manage it easily.
Help him select a watering can that not only looks cool, but which is also the right size for him to manage when it's full of water.
Never expect him to use your watering can. Even empty it will be very awkward for him to carry, and it will be impossibly cumbersome when filled with water.
Buy him the right watering can so that the watering job can continue to be fun for Pop-up Greenhouse him.