When should I fertilize my seedlings?

In this article, we will discuss the importance of providing proper nutrients to seedlings growing in inert media such as perlite, vermiculite, and rockwool. We will also explore the benefits of using auxin/vitamin-based supplements for early plant development and when to introduce fertilizers to young plants in various growing mediums.

Preparing Inert Media for Seedlings​

Before introducing seeds to a mix of perlite, vermiculite, rockwool, or other inert media, it's essential to apply a mild fertilizer solution of 300-400 ppm. This step ensures that the growing medium provides necessary nutrients and helps buffer the pH for optimal seedling growth.

Accelerating Plant Development with Supplements​

The use of auxin/vitamin-based supplements, such as Hormex or Superthrive, can significantly boost early plant development. These supplements encourage rapid growth, helping establish a strong foundation for the seedlings.

Fertilizing Seedlings in Inert Media​

For seedlings growing in rockwool or other inert media, it's important to wait until the first set of true leaves appear before applying additional fertilizer. At this stage, use a 1/4 to 1/2 strength fertilizer solution to support healthy growth without overwhelming the young plants.

Feeding Seedlings in Soil​

When growing seedlings in soil, avoid excessively rich organic soil mixes until the plants are well-established. After two to three weeks, or when the first set of true leaves appear, feed the seedlings with a 1/4 to 1/2 strength fertilizer solution, but only if the soil isn't overly rich in nutrients.

Frequently Asked Questions​

1. Why is it essential to apply a mild fertilizer solution to inert media before introducing seeds?

Applying a mild fertilizer solution ensures that the growing medium provides necessary nutrients and helps buffer the pH for optimal seedling growth.

2. What are the benefits of using auxin/vitamin-based supplements such as Hormex or Superthrive?

Auxin/vitamin-based supplements help accelerate early plant development, promoting rapid growth and establishing a strong foundation for seedlings.

3. When should I apply additional fertilizer to seedlings in rockwool or other inert media?

Wait until the first set of true leaves appear before applying additional fertilizer to seedlings in rockwool or other inert media.

4. How do I know if my soil is too rich in nutrients for young seedlings?

Excessively rich organic soil mixes may overwhelm young seedlings. If you notice symptoms such as yellowing leaves, stunted growth, or burning at the tips, your soil may be too rich in nutrients.

5. Can I use the same fertilizer solution for seedlings in both inert media and soil?

Yes, you can use the same 1/4 to 1/2 strength fertilizer solution for seedlings in both inert media and soil, as long as you adjust the application timing according to the specific growing medium.