Ok dis my 3rd time growin and i wanna get them ready for outside but i think they're too small i have failed my preivious times 1st neglected by my pot smokin friend

n the other they were just duds... so im tryin my best to not kill these...
Well... I planted around 8... 5 survived.... and on just whithered... so now i have 4 but... 3 weeks over and they havent grow to just about 2 1/2 inches... idk what is wrong i plan to plant them real soon like mid april or begin May i live in VA near A river that connect to the Chesapeake Bay so im near ponds and creeks i just want them to be at least 6 or 7 in. before i let them go in the wild and take their own course for which mother nature will provide. guys please help. you know most that can help me make a good grow. im dead broke and i use mostly sunlight or just a heat lamp but i dont like heat lamp cuz im scared they can burn them please help guys.