Contributed by: Uncle Ben
A common mistake for growers when they reach the flowering stage is
to start hitting the plants with a high P fert like 10-60-10,
continuing to use this blend exclusively, and when their plants start
experiencing a deficit of N or micros as reflected by the dropping of
lower leaves and chlorosis, they wonder why. Plants flower as a
response to long nights, not because of fert blends high in P. A ratio
of 10-60-10 is WAY to high in P. The plant will only take what it needs
and compete for other elements that may be more important at the time.
You may have heard that too much N can inhibit flowering. No
question about it, exclusive use of a plant food that is rich in N such
as blood meal, a 5-1-1 blend, or ammonium nitrate may inhibit flowering
especially if the phosphorous level is low, but most balanced blends
have sufficient amount of P to do the job.
Manufacturers/horticulturists will give you element analysis and what
effect the elements have on plant growth, but remember this does not
necessarily mean you will get better yields. Using a high P fert
exclusively during flowering can actually work against you. It's an
abundant amount of healthy leaves going into 12/12 that produce a lot
of bud, not high P ferts.
I rotate fert blends as the plant *requires* them, not because it
is "the thing to do." For example, when your plants are going thru the
stretch phase during early flowering, they may need more N, especially
if you're getting some yellowing in the lower/mid leaves. Give up the
cannabis paradigms, and give them what they need. Go back to mild high
P fert when the stretch ends, maintaining the foliage in a healthy
state of growth until harvest for maximum yields. A 1-3-2 blend such as
Peter's Pro Blossom Booster, 10-30-20, is one of the best flowering
blends on the market because of several factors - it is higher in
nitrate N and Mg. It is sold under the Jack's Classic label. An added
benefit of Peter's blends is their use of high quality, very pure salts
that will cut down on root burn.