The main thing is Ratio, and PPM. Your Potassium rate is also low.
You also need Nitrogen in flowering. Its a myth to cut nitrogen in flowering. All nitrogen is, is Protien. It makes no sense to cut protien when the plant will put on more mass, and create more hormones during flowering than any stage of its life. Nitrogen/Protien is the most important lement. The meaning of Protien is of most importance.
It basically best to have a ratio of 1-1-2 the whole way. My fertilizer is 19.5-20-39.. Weed likes the same amount of nitrogen, and Phosphorus, and 2 times the amount of Potassium.
Human beings eat protien, and our bodies turn it into Nitrogen. Plants skip this process and use nitrogen.
The word » protein « comes from the Greek »proteos«, meaning the »first one« or the »most important one«. Protein is truly the body’s most important building block. Life takes place in proteins, and store vital information in proteins.
My base formula is 4-20-39, and then I add Calcium Nitrate-15.5-0-0 and Epsom Salts.
An example is using fish as a nitrogen source. It will need to be broken down into smaller molecules before being available to the plant, and then taken up as nitrogen. Fish is protien to human beings.
In an 8 weeks flowering strain you can add Momopotassium Phosphate if your using chemicals.
Add MPK in weeks 2.5-4 in flowering for an 8 weeks strain while keeping the base formula going in ever increasing small amounts until the last 2 weeks of flowering.
If you miss the window of 2.5-4 weeks in flowering window, extra PK will do you no good.
You can also supplement more Epsom salts in weeks 4-6. The sulfur in Epsom Salts helps produce more terpenes.
Weeks 7-8 is best to cut back by about 50%-60% of the normal feed.
Flushing is also a myth, and has no scientific basis.