Homegrown Tomatoes

Posts Tagged ‘chemical fertilizer’

Now that you know what makes up fertilizer, the next question might be how to actually use the fertilizer on your tomato plants.  Even tomatoes grown organically in rich soil need some help in times of swift growth or when having lots of fruit on the plant.

There are several ways to apply the fertilizer:  foliar, liquid and granular.  Each has its strengths and weaknesses, which is what I’ll discuss in this post.  And in actuality, you may choose two or all three methods at different points in your tomato plant’s life.

Foliar Fertilizer

Foliar fertilizer is sprayed onto your tomato plants and absorbed through the leaves.   The absorption rate is swift, and many growers (including me) swear by foliar fertilizing for healthy tomato plants.

Foliar fertilizers in general should be diluted, so that there is no chance of the plant’s leaves being burned.  Good bets for organic foliar fertilizers include Terracycle, liquid seaweed and fish emulsion.

The downside for this fertilizing method is that it must be done early in the morning, before the dew dries.  This is because that’s when the plant’s stoma are open and receptive.  Later on in the day, the stoma are closed, so even if you did a foliar feeding, it wouldn’t be absorbed.

Some people say you can also foliar feed in the evening, when the stoma are once again open.  However, I don’t like to leave my tomato leaves damp in the evening because I feel it increases the risk of fungal diseases in my humid climate.

Liquid Fertilizer

Liquid fertilizer is pretty much what it sounds like; a fertilizer diluted in water.  Liquids can be used both for foliar feedings as well as drenches (i.e. pouring on the soil around the plants).

If you choose to use the liquid fertilizer as a foliar feeding, dilute to 1/2 the strength suggested on the instructions.  If you choose to use it as a drench, give the plants a light watering before applying the drench.

When using a drench, make sure you aren’t splashing any soil up onto the tomato stems or leaves, to reduce the risk of any soil bacteria that may be present  from getting on the plants.

Granular Fertilizer

Granular fertilizer is in solid form and generally sprinkled on top of the soil around the tomato plant.  Some granular fertilizers can be mixed into the soil before you transplant into your garden or a container.

Granular fertilizers can be time-released, feeding the plant over the course of several months.  However, I don’t generally recommend that because the needs of the tomato plant change as the plant gets larger and starts to bear fruit.  I feel that a granular fertilizer that is good for one month is more appropriate…unless it is a granular fertilizer made specifically for tomatoes, like Tomatoes Alive!® Plus 100% All-Natural Fertilizer.

I’m also including solid fertilizers like Jobe’s Tomato Boomers in this category, because they function roughly the same as granular.

Don’t Over Fertilize

The most common mistake is over fertilizing the tomato plants.  I know, it’s tempting to want the plants to grow big right away, but using a lot of fertilizer isn’t the way to get strong, healthy plants.  A lighter touch yields better results.

The exception is if you are growing your tomato plants in containers.  Since you need to water them more often, you’ll also need to fertilize them more often.  It’s better to use less than you think you need at first, because you can always add more.  But if you use too much fertilizer at one time, you risk burning the roots (not a good thing).

Fertilizing tomato plants is necessary for optimum growth (both for the plants and the tomatoes).  But is there a best way to fertilize?  And what about organic fertilizers versus chemical?

Let’s take a look at feeding your tomato plants.

Fertilizing Tomato Plants Organically

Organic fertilizers tend to break down slowly, releasing their nutrients into the soil over time. By “feeding the soil” the plants become stronger and less prone to attack from insects and disease. A good organic approach would be to use a combination of compost, peat, aged manure (or the bagged varietes from the store), and organic amendments such as blood meal and bone meal to create a rich soil.

With this approach, additional fertilizer is usually only necessary only once or twice a season; just after the blossoms appear, and again when a plant is laden with fruit. Good organic fertilizers for this use include fish emulsion, seaweed emulsion, and “manure tea” (fresh manure placed in a large container, filled with water, and allowed to “steep” for about a week). Make sure to dilute any such liquid fertilizer until it is the color of weak tea; even organic fertilizers can “fry” plants if applied too strong!

The organic method of gardening also benefits the environment by not adding chemicals that can upset the balance of nature. We’ve all read about how these chemicals can harm wildlife, not to mention ourselves when they infiltrate the water system. Chemical fertilizers work quickly, but they also leach out of the soil quickly.

You can read more about specific fertilizers on the organic fertilizer post.

Using Chemical Fertilizers

Having made the pitch for the organic method, I realize that not everyone is comfortable using organic methods yet. I do urge you to give the matter some thought, but if you much use chemical fertilizers, here are some general rules:

Fertilizer strength is measured by the percentage of nitrogen, phosphorus and potassium (N-P-K) to inert ingredients. For example, 6-6-6 means there is 6 lbs. of nitrogen, 6 lbs. of phosphorus and 6 lbs. of potassium per 100 lbs of fertilizer. A mixture of 4-12-6 would mean 4 lbs. of nitrogen, 12 of phosphorus and 6 of potassium per 100 lbs.

Look for fertilizers with a higher phosphorus (middle) number. Phosphorus is what fuels the production of flowers, and flowers are how fruits are formed. Try to make it a relatively balanced mix (5-10-5 would be ok, 5-10-8 would be better). You might try Miracle Grow for Roses (you read that right, roses), and use it at 3/4 strength.

Do not use a high nitrogen fertilizer! You’ll be sacrificing fruits for leaf growth!

Do not fall into the trap of thinking “If a little fertilizer is good, more is even better!” Wrong! Too much fertilizer can kill the plants.  It’s much better to use the fertilizer at 1/2 strength and fertilize a little more often.

Additional Reading

Now that you’ve learned about fertilizers, you might want to know about tomato insects and tomato diseases.  Be prepared!