Why organic fertilizer?
I advocate the use of organic, non-toxic growing methods that are safe for the gardener, the environment and for those that will consume the fruit. In addition, the fact that studies have shown that food grown organically tends to have higher nutritional value and more flavor than using non-organic methods is good enough reason for me. Plus, I have found that organic gardening is much easier on my budget, time and energy.
It's all about the soil!
The main difference between organic fertilizer and synthetic fertilizer is that the latter is much more concentrated with a high salt content. Of course tomato plant roots can't tell the difference between organically vs. synthetically delivered nutrients, but the soil that supports and nurtures the garden can tell. This salt will dehydrate and kill most of the good micro-organisms that should be living in the soil. No only are these organisms needed to break down the nutrients added to your soil to make them available for plants, but they maintain soil structure and quality. If you kill them, your plants will become dependent on your adding more and more synthetic fertilizer while your soil breaks down and erodes away. This means more work and more expense for you.
Start by feeding the soil where the tomato plants will grow. Addition of organic material in the off-season feeds the micro-organisms in the soil improving nutrient and water retention year-round. You can easily accomplish this by composting directly in your garden beds. During the growing season, use compost, mulch, foliar sprays and organic fertilizer to feed plants and soil.
What to feed tomato plants
Fortunately, today there is a multitude of pre-mixed organic fertilizer products on the market. First it's important to know that there are three stages of tomato plant growth that have distinct fertilizing needs.
Organic fertilizer at the seedling stage
Tomato plants started from seed will need feeding once they develop their true leaves (second set of leaves to emerge). At this stage, they need mostly nitrogen for leaf and stem growth along with some potassium and phosphorous.
One easy way is to add a bit of an organic liquid fish emulsion product to the watering container to make a diluted solution for watering the seedlings. Do this about every two weeks. Liquid fish fertilizer is a byproduct of the fishing industry.
An even easier way to fertilize seedlings is to start out planting the seeds in a organic, pre-packaged seed-starting soil.
Organic fertilizer for the potting-up stage
When tomato seedlings have been transferred into 4” containers, they will like continued use of the liquid fish emulsion. Or again, they can be planted in a pre-packaged organic potting soil mix that contains everything already. I do both: my tomato plants are potted in an organically-certified soil mix containing all the necessary nutrients and I throw a little fish emulsion in with the water every two weeks.
Organic fertilizer for the garden-planting stage
When tomato plants are going into the garden, they will need less nitrogen, more phosphorus for root growth and more potash to encourage flowering and fruiting. Too much nitrogen can result in more leaves than fruit. In order to keep things as simple as possible, I use Gardener's Supply Company (GSC) Organic Tomato Fertilizer. I just follow the package directions that call for fertilizing twice during the lifetime of the plant: First, it goes into the planting hole for each plant when I transplant into the garden --Second, it gets worked into the soil around each plant just about the time when the plants begin to produce blossoms.
Some gardeners create their own blend of tomato fertilizer by combining specific organic ingredients. Gary Ibsen provides a list of his favorite tomato fertilizer ingredients in his book, The Great Tomato Book (see references below).
Another option is to use foliar spray. This is a very diluted solution applied directly to the leaves. If not diluted properly, the solution can burn foliage. Seaweed solution works the best, according to author Bob Flowerdew, because it is rich in almost every element especially potassium. Mr. Flowerdew says that it works like a "vitamin" producing fast results--plants become more green and healthy while better resisting pests and diseases. This is because plants absorb nutrients through their leaves almost twenty times faster than when they are applied to the soil, according to Gary Ibsen of Tomato Fest Heirloom Seeds.
For foliar feeding, I alternate between sprayings with compost tea and a kelp/seaweed solution. This is recomended to do every 2 weeks or so but I tend to do it randomly when I think of it. I'm just not that disciplined.
It's best to apply foliar sprays when the weather is cooler such as in the morning or evening. As long as the solution is diluted properly, there's no worry about applying it too much.
The Gourmet Gardener. Bob Flowerdew. 2005. Kyle Cathie Unlimited. Pages 16-18
The Great Tomato Book. Gary Ibsen with Joan Nielsen. 1999. Ten Speed Press. Pages 37-40.
Return from Organic Fertilizer to Grow Tomato Sauce homepage.