Is it normal to get itchy when working in the garden and to go away when showering?

While I don't think: this happens to everybody, it isn't terribly uncommon. Certain individuals, especially those susceptible to eczema, have sensitive skin. Numerous irritants/allergens can be found among plants, weeds and grasses. Best option: wear protective clothing including gloves (vinyl), long sleeves and pants tucked into socks. Apply OTC barrier cream/lotion with quaternium-18 bentonite where exposed.