Plants, like kids, need a well-balanced diet to grow up healthy and strong. However, tomatoes are an extra special case.
To get the most out of your tomato plant, you’ll need to give it various fertilizers over its lifetime, with each life stage having its own requirements.
Perhaps the most confusing of these is the seedling stage, which begins when the seedling has gained 2 to 3 sets of true leaves.
During this time, the plant will begin demanding more nutrients as it heads toward its juvenile phase. But there are a few different camps for feeding a tomato seedling.
Let’s take a few moments to look at different fertilizers as we seek to find them.
The Best Fertilizer For Tomato Seedlings
As a little spoiler alert, there are actually two options, and you’ll have to test both to find out which is best for your own tomato garden.
Also, note that the best practice is to get your soil tested annually and adjust the NPK accordingly. Thus, if you are testing your soil, the NPK given here is meant as a plumb line, not a solid rule.
Granular vs. Liquid-Soluble
Starting off, we must address one of the biggest debates in fertilizing: whether to use granular or liquid-soluble fertilizers.
A lot of sources out there absolutely swear by granular, time-release fertilizers.
Their biggest argument is that you only need to feed the plant a few times during the entire growing season; thus, this method saves time while giving your plant everything it needs.
Sounds great, right? Well, unfortunately, none of the above is actually true.
In reality, granular fertilizers give your plants all of the nutrients, but they need more than the amount they need.
For example, nitrogen will break down more easily than zinc. When you use a granular formula, the plant will get a burst of one nutrient while the ground struggles to break down another.
This can lead to the plant being both overfed and deficient simultaneously.
Thus, you might find yourself amending the soil with eggshell tea or other amendments, even though the fertilizer SHOULD have provided everything your plant needs.
Liquid soluble fertilizers are precisely the opposite. Because this fertilizer dissolves in water, you can feed your plant while you water it, thus eliminating a step.
In addition, the fertilizer is designed to break down evenly, meaning once you’ve mixed it into the water, EVERY nutrient is dissolved and ready for absorption.
These fertilizers soak directly into the soil and can be consumed by the plant within seconds or minutes of application.
But perhaps the biggest advantage is that you can tweak the dilution as needed to get the perfect amount your plant needs every time.
Of course, there are still a few drawbacks, such as the fact that dissolved fertilizer has an incredibly short shelf life and should be used within a day.
You will also need to apply it more often, although this involves dumping a scoop or two into your watering container of choice and stirring.
Overall, however, there’s every reason always to use a liquid-soluble fertilizer and avoid slow-release formulas.
Tomato Nutrition 101
This is another major point of contention, and we’ll be perfectly honest – there are not one but TWO right answers here.
Let’s begin by touching upon what NPK is and what nutrients your plants need.
The NPK ratio on the fertilizer package is about the three most important macronutrients: nitrogen (N), phosphorus (P), and potassium (K).
Each of these nutrients will affect certain parts of your plants more than others, although they are all necessary for overall health.
Nitrogen encourages more foliage and will make your plant fuller and greener.
Phosphorus is primarily responsible for encouraging the plant to produce blooms and fruit, although excessive amounts can cause potassium to be leached from the soil.
Potassium has a similar role in both plants and people, encouraging strong stems and boosting the plant’s immune system.
Additionally, tomatoes need several other nutrients to grow properly, which are often listed on the back of the fertilizer package:
You can already see that a tomato seedling will need plenty of nitrogen and a decent amount of potassium but not as much phosphorus. And that’s where the two options come in.
The Great NPK Debate
As mentioned earlier, the best thing you could do is to test your soil annually to adjust your NPK as needed.
However, many people don’t do this, which is why there’s more than one solution to the question of the best fertilizer.
For those who wish to play it safe, a basic 10-10-10 NPK fertilizer is perfectly fine and will still provide a healthy plant.
Many opt for this particular ratio because it can be used on other plants while still having great results. However, the other option is a high nitrogen mix of 26-6-16 diluted to ¼ strength.
This option is much closer to what the plant actually needs, but it also means you’ll want to pay attention to your soil’s nutrient levels.
This makes it more effective than the balanced formula but with a slightly higher risk if the soil already has an abundance of nutrients.
Don’t Be Afraid To Experiment!
At the end of the day, liquid-soluble fertilizers with both 10-10-10 and 26-6-16 ratios are equally viable. It will generally come down to the quality of your soil and personal preference as to which of these two will work best for your tomatoes.
Don’t be afraid to grab a small package of each and test them on separate plants to see which one works better for your own tomatoes.
If possible, test the soil each spring so you can tweak the NPK of your fertilizer accordingly, but this isn’t essential.
Also, feel free to tweak the dilution a little to get the perfect results.
Finally, remember that you will need to change the fertilizer when your tomato plant reaches its next growth stage. While the 10-10-10 gives you a little leeway, the 26-6-16 will need to be exchanged for a fertilizer that gives a more precise ratio for what the juvenile plant will need as it approaches full maturity.