Controlling aphids is actually easy, though somewhat time consuming. A sharp stream of water will knock the little buggers off the plant, although a hose nozzle may be too strong - especially for tender plants like peas.
Another effective alternative is insecticidal soap. The soap washes off the aphid’s protective waxy coating and causes dehydration, thus killing the insect. Insecticidal soap spray is economical, nontoxic, and environmentally safe both indoors and in the garden.