For young hatchling nymphs you can use tall faunariums or kritter keepers as these will keep the humidity up better for the delicate and prone to dehydrating nymphs.
Never get your food plants from garden centres or near farmer fields or anywhere you suspect pesticides to be used. Pesticides will make your stick insects very sick and eventually result in death.
If there is any mould on your cage floor caused by moisture and poop, its definitely time for a clean out. Stick insects like Praying mantis get sick from mould spores and can/will lead to death.
Baby stick insects are not the brightest so make sure you plug up any access to water with kitchen towel or wrap up the base of the stems where they peep out of the jar/glass with tin foil or cling film.