Options for Fertilizing Vegetables; Organic vs Conventional? Soil vs. Foliar?

Viragrow's Kelp Meal

Q. I was reading an article from Linn Mills about foliar fertilization,Linn was saying to spray tomato plants with phosphorous. I read an organic article in which they use fish-seaweed extract. In your opinion which is better to use? I see that Viragrow sells these products. I follow you on Xtremehorticulture great advice,I have tried vegetable gardening in ground to no avail this year I built a couple of raised beds-with all the articles i am reading from yourself and Linn i know i will not fail.

A. We want you to decide your options, not us. Yes, we carry Kelp Meal. It is a good product but we are not here to sell you an agenda. We sell both conventional and organic fertilizers - your choice. 

Viragrow's conventional preplant fertilizer
containing nitrogen and phosphorus.

You want to give tomatoes a complete fertilizer at the time of planting. You can use organic sources or conventional fertilizers. The problem with organic sources at the time of planting is that they last so long in the soil. Conventional fertilizers that are quick release will have the nitrogen that stimulates the growth gone basically in 4 to 6 weeks. 

Having the nitrogen disappear in 4 to 6 weeks is a big asset in the promotion of flowering. If this nitrogen is present in high concentrations, it delays flowering and promotes stem and leaf growth. In our climate, we want the tomatoes to get large enough to support fruit and then we want the plant to shift to flowering and fruit production. This is typically in a few weeks. 

For this reason I like conventional fertilizers at the time of planting and then following up with organic sources. Foliar feeding tomatoes with high phosphorus fertilizers is a great idea. You really want to keep that nitrogen away from the plants until they begin to set fruit. Once they begin to set fruit, then you want to feed them with small amounts of fertilizer monthly. 

Viragrow's Organic
high nitrogen fertilizer

This is particularly true when you start harvesting fruits in June or July. This contradicts the idea to never fertilize vegetables during the heat of summer. I disagree 100%. This is the time that they need small amounts of fertilizer continuously. This fertilizer should be focused on the type of growth you desire. With leafy vegetables that are not expected to flower and produce fruits, high nitrogen fertilizers should be used. 

On vegetables which we expect to flower and fruit, we want to focus on high phosphorus fertilizers and keeping our nitrogen levels much lower. Regarding the third number on the fertilizer, potassium, this number should always be high. Potassium is very important in improving the general overall health of the plant and its improved growth during high temperatures.

At the time of planting I use a very old-fashioned fertilizer, 16-20-0. I also improve my soils with compost at this time. If my soils require a high percentage of compost because they are more difficult to dig and plant, I only add phosphorus as triple super phosphate or bone meal. I like bone meal a lot.

Viragrow's organic high
phosphorus fertilizer.

Regarding foliar feeding, you should have two types of fertilizers for foliar feeding. One should be a high nitrogen and low phosphorus fertilizer and the other should be a high phosphorus and low nitrogen fertilizer. If at all possible, these two fertilizers should both be at least moderate in the amount of potassium it contains. Potassium will not stimulate growth or flower production unless for some reason it is missing. In most gardens soils, it is not.

The high nitrogen fertilizer to be applied as a foliar spray should be used on leafy vegetables and flowering/fruiting vegetables in their very early stages of growth. This fertilizer should be avoided as a foliar spray when they reach about one half of their mature size. At this time you should switch your foliar spray to a high phosphorus spray. 

Foliar sprays should be applied once a month when temperatures are not hot. This can be in the early morning hours or evening hours. I prefer morning hours so that the leaves have a chance to dry before it gets dark. When using foliar sprays you should also be using a wetting agent. 

Viragrowis high
nitrogen water soluble (foliar)
fertilizer for leafy green vegetables.

People can and do use liquid detergents for dishes. I don't like to see people using these because of all the contaminants in these detergents. However, I realize they will continue to use them. It is best to use a wetting agent or surfactant that is specifically designed for foliar applications. There are several available. I really, really like the one I have found at Viragrow called EZ Wet. I like it for a variety of reasons but any of those will work.

Bottom line:

• improve your garden soil each time you plant.
• Use a high phosphorus fertilizer mixed with the soil at the time of planting
• apply foliar fertilizers one month after planting
• use high nitrogen fertilizers for leafy green crops monthly
• use high phosphorus fertilizers for flowering and fruiting crops monthly
• never, never forget about potassium and either get it into the soil or apply it with the foliar sprays
• during the heat of the summer, reduce the amount of foliar fertilizer that you apply by half but still apply it monthly



One of Viragrow's water soluble high
phosphorus foliar fertilizers.

• apply foliar fertilizers during early morning hours during the summer

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