One of the areas where a lot of newer, and even fairly experiened, gardeners get a little nervous is the topic of fertilizing young plants and seedlings. We’ll give you our opinion and thoughts on the matter!
Yesterday, we discussed the anatomy of the seedling. Specifically, embryonic and post embryonic leaves. Another way to interpret this is that from the point of “first true leaves” forward, the seedling is on its own for nutrition.
For the most part, most potting soils that you might use in the nursery will offer some level of nutrition. This might be compost, worm casting, light fertilizers or other organics. Whether this is “enough” or “complete” nutrition to get all the way to transplant size is highly variable.
We opt to fertilize our seedlings, just to ensure they have everything they need nutritionally. We generally start this practice fairly soon after the plant develops its first true leaves and can utilize external nutrition. For seedling fertilization, we strongly prefer water soluble fertilizers since they’re easy to apply to seedlings.
Now, this is a bit of a delicate process as your seedlings don’t need a lot of nutrition. There are ferts that are designed for seedlings, restricting the NPK to levels appropriate for seedlings. You can also do this with other ferts, for example by applying a quarter dose as opposed to the full dose. Less is more in this case.
Part of our preference towards early fertilization is our perspective as subarctic growers. We see ourselves in a race, trying to power through a very short season with little room for error. We want to eliminate all road blocks in plant growth, thus maximizing growth, maturity and harvests. When time is limited, speed matters.
There are other ways to do this, too. For example, a number of potting soils (e.g. Miracle Grow) are infused with NPK. These are poor choices for germination, but great for transplanting. Whether adding NPK is right for you depends on many variables that only you know.
If you opt for this process, we recommend easing into it. Try growing without NPK additions. Then, if you hit various nutritional issues in the nursery, add just a little bit of NPK. If you find this isn’t enough, increase application rates to maintain growth. Eventually, you find the balance for your soils, product choices and specific nursery’s variables!
