Hemionis Arifolia are tender ferns with heart shaped leaves. Adorable to look at and pet friendly, too! As pretty as she looks, she's not for the faint at...heart. Some TLC is definitely required as ferns crave higher than average humidity levels, warmer room temperatures and prefer filtered water at room temperature. The Heart Fern also does really well in a vivarium or terrarium because of its tendency to thrive in high humidity environments. To increase the humidity you can add a pebble tray under its pot or keep it in your bathroom provided there is enough light. Ferns need only a little fertilizer, once a month is enough.