There is not much that can be 'done' to fix the problem because I think its the doing that is partly causing the problem sorry. The problems usually begin before plants are switched to flowering. Often times too much watering and too much nutrients and additives result in the opposite affect of what is written on the bottle.
The roots end up shocked and their growth slows. To make matters worse for the plant, there are additives for every little leaf issue, and more additives are put into the soils bringing with them salts and more shock to roots further inhibiting their ability to recover.
The next problem is this idea that the decision to switch to flowering often is determined from the plants height, the amount of nodes, and arbitrary veg times stipulated on some grow videos.
The result is that switched plants are not in the position to produce bud. Their roots are either under developed, or in shock, sometimes rotting, sometimes with disease from over feeding, over watering etc. Roots also have not have the chance to spread through the growing medium and occupy the diameter and circumference of the pot. A sign of this is the lack of filling out of plants at least the majority of the foliage filling out to the pots rims. Plants stretch outward usually at least as much as roots stretch out to fill the pots.
This reduces their ability to handle the shock of flowering, the shock of the loss of nitrogen, the increase of potassium and the shutting down of their growth cycle. This begins and appears usually at about the first or second week of budding but is often missed until week 4 when the metabolics of plants go into hyperdrive.
The lack of proper root development during vegging also results in undeveloped cell walls, stems that are like celery stalks, they may be thick in diameter but the stem wall itself is thin. The ability of plants to then deliver the needed extracts from the soil to the top of the plant and then down to the lower branches is stunted. This is seen by the onset of early leaf color disappearing and what looks like nitrogen deficient and potassium deficient leaves.
Following on from that, growers are then instructed by various plant problem sites, books and videos that their plants are suffering from whatever deficiencies, or soil issues which means that the plants end up being assaulted with yet more nutrients, additives and unneeded watering further hurting the roots. Even worse is when growers determine that it is a root problem and then are sold additives to be fed into the roots to sort the problem, however they usually make things worse by that stage of root shock.
End result, plant foliage that begins dying at week 4 instead of what you would see at week 7-8, necrotic leaves and in some cases cooked plants.
The answer is prevention and doing away with that mechanical way of determining when to switch your plants. Water thoroughly then let that pot totally dry out (even if it takes ages to dry), then water again.
Most root problems will be avoided doing this - excessive watering is almost 80% of the cause of most plant deficiencies. Growers also have to learn to read their plants with almost a 'gift' like manner rather than like playing music from a music sheet so to speak.
Some of the signs you are looking for are as follows:
- What is the speed in which your plants are drying out the pot, is it slow, medium, fast, an increasing metabolism is a good sign plants are preparing to be switched.
- Are the plants stretching outward as much as they are growing upward, this is a good sign that roots are filling out the container the plants are in
- Do the leaves look too green, patchy, tips burning, spots appearing, leaves dying or otherwise, this is a sign that the root area is under stress (discounting any other grow room issues).
- Are the leaves stretching outward, upward or drooping, these will tell you whether there is too much moisture in the soil, or too much nutrient, or too much heat on the leaves.
- Are the plants stretching with big gaps between nodes, this is a sign there are issues going on, other than genetics, this can be lack of light lumens or heavily stressed plants
- Are bugs being attracted to your plants. If your plant is becoming a bug magnet it is sometimes a sign the plant is also sick, plants emitt an odor that attracts bugs when they are sickly.
All these and more are signs to look for which tell you that your plants are not ready to switch to flowering...and that is without even covering the issues of room temps, pH and EC which are usually pointed to as the source of most problems.
Allow your plants the time they need to veg into adults with fast metabolism and full leaf sets and they will act like adults when producing buds for you.
Sorry I cannot be more directly helpful but I believe a lot of the deficiency issues I read about online stem from this issue alone, shocked roots.
