Improving Crop Size and Quality

The size, quality, and flavor of the fruits and vegetables being grown and sold are important factors that buyers consider when purchasing product from growers. By extension, these pieces also become important factors for us growers, since we need to care about what the consumer cares about.  

Hopefully you get paid based on how good a job you do growing your crops. If not, then that is a totally separate conversation. If, however, you get paid based on how great a job you do, then you should  constantly be asking yourself how you can improve.  

Influencing crop production in a positive way usually means that we need to have the basic balance of  nutrients, then focusing on specific nutrients at specific critical points of influence. Influencing fruit size and quality is no different. In general, the concept is fairly simple: a focus on trace minerals and phosphorus for blossoming and pollination, then calcium and boron in the cell division stage (right after blossoming and pollination), then switching to potassium and trace minerals during the fruit fill stage, with nitrogen as needed.  

Let’s expand on these concepts:  

Blossoming and Pollination

The important factors to trigger bloom on a reproductive crop are the reproductive minerals, especially phosphorus and manganese. The ammonium form of nitrogen may also be used. However, just having bloom doesn’t mean that the crop pollinates. Many crops require bees for best pollination, with some crops requiring seven visits for complete pollination.  

The higher the brix content, the more interest a bee will have in pollinating the crop, and the more  efficiently it can do so. Therefore, it becomes critical for a crop to have adequate levels of the  photosynthesis minerals, including the critical trace minerals iron and manganese, so that the crop is photosynthesizing at a really high level.  

In addition, just because the bee does its job is no guarantee that the plant successfully pollinates. If  the trace minerals copper, zinc, and boron are inadequate enough, the pollen tube collapses and the  pollen never gets where it needs to go for successful pollination. This is more of a problem on some crops than on others.  

Cell Division

Right after successful pollination comes the cell division stage, which is where we start seeing tiny fruit appearing. During this stage, one cell divides into two, two into four, four into eight, eight into sixteen, sixteen into thirty-two, etc. The maximum potential size of these fruits is determined by how many cells are produced. The maximum potential quality is determined by how much calcium is in each cell. By extension, this means that boron and manganese are important again, because of their influence on calcium. About 60% of the calcium that goes into the fruit will go in during this 10–14-day stage.  

We can have some impact on the cell walls of the fruit later on, but most of it occurs during the cell division stage which makes it very important to have plenty of calcium available early on. 

Cell Expansion / Fruit Fill

Once past the cell division stage, the crop goes immediately in the cell expansion stage, more commonly called the fruit fill stage. This is when actual fruit size is determined, mainly by potassium, but also by sugars, nitrogen, and boron.  

The challenge is that many times this is when the issues start showing up. Maybe the fruit is too small and the grower tries to blow them up using potassium or water. This works well only when enough calcium was used early, during the cell division stage. If the available calcium levels were inadequate, the potassium or water applications create a large fruit that is no longer structurally sound because the calcium has become diluted too much. In that case, the crop will not have a good shelf life. If severe, the fruit will split.  

In summary, it may be helpful to think of the cell division stage as the rubber on a tire. In order for the tire to hold high air pressure, it needs a strong tire. So it is for fruits and vegetables; imagine calcium as being the rubber part of the tire, having to be built well first, then imagine potassium as the air. Our goal should be to have lots of calcium going into the fruit early, then lots of potassium later to fill the  fruit. 

All-Natural Fertilizers and Soil Amendments for Higher Quality Fruits and Vegetables 

Accelerate and a trace mineral package (such as MicroPak) are good products for addressing the minerals we discussed during blossoming and pollination. During cell division, ProCal is a good option. ProCal is micronized to 1 micron in size, which is very very small, then chelated with plant derived amino acids for rapid uptake. For fruit fill, Pro-K 0-0-20 is a great option because of how available it is for plants to absorb.