I've seen MUCH worse. If the redness of the petioles is visible from the top of the leaf, as reddening VEINS, you really need to worry, but actually your plant doesn't look bad to me.
You can get all sorts of stuff online... make sure whatever you get has micronutrients in it. The cactus stuff is interesting because cacti are one of the few classes of plants that require virtually NO nitrogen from the soil for growth! So cactus nutes are good for bloom! Mg probs... can't tell without seeing the leaf surface.
stinkyattic Reviewed by stinkyattic on . Why do I always see Red? All the plants I have grown always get red veins on leafs and stems, espically in the early stages of life. for example... 3.5 weeks old. All Sativa Dominant except the One Indica which has bigger fan leafs also the most purpal veins right up the stem of the small plant. ProMix with added perlite Ph 7, Ph Runoff was 6.5, Water with 2.5ml of Pure BLend Pro Grow per gallon, and superThrive, Ph 6.7-6.8. Water with every watering. Recomended Dose of Nutes on bottle is 7ml per gallon for Rating: 5