Phosphorus helps roots of newly planted vegetables

March 07, 2009|By JEFF RUGG / Creators Syndicate

Q: How much and what kind of fertilizer should be used for tomatoes? Please describe fertilizer by ingredient ratio, such as 10-10-10, if possible.

A: The first thing that should be done is to have your soil tested. This is more important if it is a new garden. Follow the directions that come with the container from the testing laboratory. It is often a good idea to label the soil as having come from a vegetable garden or a lawn because the testing lab is used to giving results to farmers. Otherwise, your results may come back being listed in tons per acre.

Without a soil test, garden experts often recommend that one pound of a general fertilizer such as 10-10-10 or 15-15-15 be worked into the top 4-6 inches of soil for every 100 square feet of garden. A garden soil that has lots of organic matter or compost may not need any additional fertilizer.


It is often helpful for newly planted vegetables to get a dose of a starter fertilizer. It is important to get roots established and phosphorus helps to do this. Phosphorus is the middle number of the three, so a ratio of something between 10-30-10 to 10-50-10 would be good. Follow the label directions and pour the liquid into the soil right around the base of the plant.

It just so happens that phosphorus is also beneficial to plants trying to produce flowers and fruit. Potassium also helps, so fertilizers two to five times higher in the middle or the last two numbers than the first number will be good. Exact numbers are not important, just the ratio of low nitrogen to higher phosphorus and potassium.

If you are growing a leafy crop like lettuce, then a higher nitrogen fertilizer is better, since it promotes leaves not flowers.

Slow release fertilizers are generally best. They continually release fertilizer to the crop as it grows and needs the nutrition. They can be in the form of stakes or granules. Fast release fertilizers can wash out of the soil where they do no good to the intended crop and may pollute lakes, streams and groundwater.

Compost is a good slow release fertilizer, besides adding beneficial organic matter. All garden soils from sandy to full clay will benefit from adding compost.

Q: I was thinking of using Styrofoam cups for starting my vegetable garden plants from seeds. Will they work and can I plant them in the ground with the cup, or do I have to remove the cup? Will removing it damage the roots?

A: Styrofoam is one of those products that is great for what it does, but maybe not so great for some other uses. It is made by adding gases into heated polystyrene. The foam that comes out is over 95 percent air. It is a great insulator as it is a poor conductor of heat, so it is used in hot beverage cups.

Styrene is named after the styrax plant. It produces a resin that can be used to make synthetic rubber. Styrene is found in many foods, including nuts, meats and fruits. Polystyrene is a synthetic material that is used in rubber and plastic parts for boats, carpeting and food containers. It provides an economical and sanitary product that makes a very small percent of the material sent to landfills, according to the EPA.

There are newer products used for food container packaging that are made from corn, sugar cane and beet products and are also good insulators and very sanitary. They may not currently be as economical, but they are heading in that direction as more restaurants use them.

While recycling is technically possible, it is rarely done, except for packaging peanuts. It does not biodegrade, so using it in your garden will not work very well. It can be used to start the seeds. The cup will hold the soil for the seedlings and it will need a drainage hole in the bottom. When the plant is ready to go in the garden, gently slide it out of the cup. If the roots are wrapped around the bottom of the soil, spread them out as you place them in the hole. Save the cups and use them again for several years.

E-mail questions to Jeff Rugg, Kendall County unit educator, University of Illinois Extension at To find out more about Jeff Rugg and read features by other Creators Syndicate writers and cartoonists, visit

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