Magnesium deficiency.
You can't do much to fix a deficient plant in such a tiny pot- the soil conditions fluctuate more wildly and you could be providing ample Mg but the plant may not have the conditions to uptake it due to moisture, pH, oxygen problems in the soil.
That plant needs a gallon pot of LIGHT soil. Read the sticky in my sig. You may foliar feed with a weak solution of Epsom salts (1/2 teaspoon per gallon of warm water) to keep that deficiency from getting worse until the soil conditions are changed.
stinkyattic Reviewed by stinkyattic on . leaf problem, and i am clueless hello there, i am yet another newbie with a sickly plant, ive read loads of these plant problem threads but havent found anything that looks quite like this, any help would be deeply apreciated. just to warn you, im doing this very lo tech the plant is at present under a 20 watt energy saving bulb 24/7 and was planted in bagged soil. its about 5 weeks old and ive fed it once with rose ferteliser i bought in poundland. ive no idea what the ph level is, so that may well be the problem. im Rating: 5