Beginning Gardener Series: Fertilizing seedlings and plant starts

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Fertilizing seedlings and plant starts

You have planted your own seeds, and they have sprouted now what?  Seedlings are no different than their fully grown counterparts, and they need to be fertilized just the same. 

When it comes to seedlings, you should begin fertilizing as soon as they have their first set of true leaves.  What are true leaves?  When seedlings sprout, the first leaves you see are Cotyledons.  You will notice that these leaves all look the same regardless of what you are growing.  These leaves provide the plant with all the nutrients necessary until the true leaves appear.  True leaves are the second set of leaves to grow and look like the adult leaves will look on a plant. Once these leaves appear, the plant can now begin the photosynthesis process.   Once you see these leaves, then it is now time to start fertilizing.

Why do we need to fertilize?

When a seed germinates, it has all the nutrients necessary to start its life off.  What happens when those nutrients run out?  Pests and diseases have the opportunity to move in and destroy the seedlings.  Regardless of the size of the container you start the seedlings in, they have a small root system.  We are supposed to be helping strengthen their immune system, helping them to get off on the right foot.  So that when we plant them in the garden, they have everything necessary and are prepared to thrive. 

What to use as fertilizer

Anything you would use to fertilize the mature plant is capable of being used for the seedlings, just at a diluted rate.  During the seedling stage, plants need an all-purpose fertilizer.  That is a fertilizer where the NPK values are close to equal, 4-4-4, or 20-20-20.

I don’t think you should use 20-20-20 fertilizer.  That is synthetic fertilizer, and that kind of fertilizer can and will kill all the microbial and soil life that we are working so hard to create. How do I know it is synthetic and potentially harmful? Well, organic fertilizers do not have double-digit fertilizer numbers.

Using an all-purpose fertilizer is a way to ensure the plants are receiving a balanced diet of all the necessary macronutrients.  Some crops, like tomatoes, benefit from fertilizers that are rich in micronutrients as well.  Such as fish fertilizer or kelp meal.  If you notice the underside of your tomato leaves turning purple, apply either one of these.  They contain trace minerals that will solve this issue.  Honestly, I prefer to feed my plants compost or worm castings teas instead of all-purpose fertilizers.

How to apply fertilizer

Before we talk about how to apply the fertilizer, let's make one thing clear; DO NOT FEED SEEDLINGS A FULL-STRENGTH DOSE OF FERTILIZER!  If the nutrient says to mix 30 ml/ gallon of water, start by using 1/10 of that and mixing 3 ml/gal.  Why? Well, the seedlings do not have a fully-grown root system, so a full-strength dose can cause harm, burning the leaves or even killing the plant.  Nutrient burn is when the fertilizer or nutrient solution is too strong for the plant and causes more harm than good.  This damage can look like burnt edges on the leaves or the plant merely dying, so keep that in mind.

There is no right or wrong way to apply fertilizer.  Spray it on leaves, water it in on top of the soil, or fill the tray underneath your starts and allow the roots and planting medium to absorb what it needs.  The choice is up to you.  Personally, I water the trays from below or spray with a sprayer. Watering the seedling from above has the potential to lead to all sorts of fungus and disease issues. Those are the kind of problems you need to avoid.

Whatever you decide, remember these seedlings are depending on us to become successful. If you pay close attention a to them when they are young you will be rewarded in the future. More fruits, vegetables, flowers, and fewer problems.  Equip them with the necessary tools to thrive.

Damn gardening really is just like life.




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