Different experiments in order to determine the polyamines (PA) putrescine (Put), spermidine, (Spd), spermine (Spm) and cadaverine (Cad) effect and concentration in corn (Zea maysJ cv. M8 510, c.v. M8 513 and a regional type; and in Sietecueros (Tibouchina lepidata) seedlings were made. PA were determined during ear of corn formation by High Performance Liquid Chromatography (HPLC). Put was the most abundant followed by Spd and Spm. Cad was detected but with unmeasurable values. Applied PA modified growth patterns of regional corn and so, ear of corns that normally don't fill out grain, was developed. Besides, there was size increase and the number of grains in each ear of corn was higher. In corn plants, affected by chilling (_30 C/6 Hr), height growth was suspended, leaves were burn out and the number and size of corn ears decreased. PA treatments reverted the negative effect caused by chilling, keeping plant growth normal; furthermore, normally inactive ear of corns were released, resulting in higher grain yield than in controls. In slow growing Sietecueros seedlings, PA applications released plant growth, reaching more than 100% of height increase in treated seedlings in relation to control.