How to Care for Plant Seedlings
The Spruce / Margot Cavin
When you start seeds indoors, the tender seedlings are dependent on you for all their needs. This includes getting fed. Some gardeners think their seedlings will grow faster if they give them fertilizer right away. However, while those tiny plants may look helpless, they don’t need anything other than water, warmth, and light for their first few weeks. They are capable of feeding themselves up to a point. After that, it’s time to start feeding them, following a few standard guidelines.
When to Start Fertilizing Seedlings
When seedlings first poke out of the ground, they are still feeding off the food stored in the seed. The first couple of leaves that form are not leaves at all. They are called cotyledons or seed leaves, which are part of the seed or embryo of the plant. Cotyledons contain the remainder of the stored food reserves of the seed, and they keep the seedling fed until the first true leaves sprout and the plant can begin photosynthesis.
Usually, the cotyledons disappear shortly after the first true leaves form and begin photosynthesizing. It is at this point that the seedling can use a little boost of fertilizer.
Before you reach for the plant food, make sure you haven’t used a potting mix that already contains fertilizer. Some do, and some don’t. If the mix has fertilizer, you shouldn’t need to add more. For the future, because seedlings can initially feed themselves, you don’t need to use a potting mix with fertilizer for starting seed. Using a mix without fertilizer is cheaper, and more importantly, you can control how much and what type of food your seedlings get.
Seedlings tend to need a fertilizer that’s high in phosphorous. Phosphorus stimulates root development and is a component of photosynthesis. Look for a 1-2-1 N-P-K (nitrogen-phosphorus-potassium) ratio on the fertilizer label. A liquid or water-soluble fertilizer is typically the easiest and quickest way for the seedlings to access nutrients. You’ll also have a choice between organic and synthetic fertilizer, which often comes down to personal preference.
- Synthetic fertilizer: If you are using synthetic fertilizer, feed your seedlings weekly. However, it’s often wise to dilute the label’s recommendation by at least half. Tender seedlings can be easily burned by too much fertilizer. Young seedlings commonly can get away with a quarter of what the label recommends for full-grown plants.
- Organic fertilizer: There are several liquid organic fertilizers available, though they sometimes can be hard to locate. A mix of fish emulsion and kelp can also give your seedlings the nutrients they need to get started and reduces the risk of burning your seedlings. As with synthetic fertilizer, give your seedlings a dose of organic food weekly. Unless the product is labeled specifically for seedlings, dilute it by at least half the recommended dose. It’s better to give your seedlings a little food regularly than to risk burning those tender roots with too much fertilizer at once.
- Another option: Mix a granular organic fertilizer into the potting soil. Many gardeners do this when their seedlings are ready to be moved from their starter containers to larger pots. However, granular fertilizer can take a while to release nutrients and impact the plants, so adding it when you are starting your seeds is often a better option. Try to add it to the lower layer of potting mix, and don’t let it come in direct contact with the seeds. Even organic fertilizers can burn if you use too much.
Knowing When Seedlings Have Had Enough Food
How much to feed seedlings will take some experimentation. Keep an eye on how well your seedlings are filling out. Too much fertilizer can cause a flush of tender, lanky growth, which is not what you want. Ease back on the fertilizer if this is the case. At this point in a seedling’s development, you should be more interested in growing a healthy root system than sending up a lot of green leaves.
Moreover, each plant—even those of the same species—will react a little differently to fertilizer. But in time you should get a feel for how much food it takes to keep your seedlings robust while they build up the strength to be moved outdoors into the garden.
New plant seedlings can feed themselves up until their first true leaves appear. Here are tips on how, when, and what to feed your seedlings.
When to start feeding seedlings ?
I did use the search . chances are though I didn’t correctly word it.
I want to know when to fertilize seedling or my new plants. How old or how tall etc before you start to fertilize them. I do not plant to feed them full strength but I need to know when do I start. I have them in a soil designed to start seeds or clippings.
They are real pretty and they look healthy so far!
What’s everyone’s favorite fertilizer? I have yet to find bat shit available in any local shops (though I expect to see plenty of them flying around very soon). I was going to use a dilute solution of Miracle-Gro, but I’m not sure that it’s got the right ratio of nutrients.
So far my little babies have the first real leaves (the jagged leaves) and that’s it.
first of all, it totally depends on what you start with. with prenuted soil, you have to be very careful not to overload, and it’s very easy with plants only a couple weeks old. it’s much easier to start with soil that is barely – if at all – fertilized. Promix, for example, is buffered and is lightly fertilized. This makes it easier to gradually build up the nutes. And for the love of god stay away from gradual release.
I use botanicare pro grow and bloom. I strongly prefer organic fertilizer, and since it is so widely available I see no reason not to use it. What is best depends on both your strain and your medium.
I don’t know what strain, as these are seeds gleaned from my last purchase. The soil is a mix of Miracle-Gro (not the water retaining new stuff) and highly composted dead tree that we used for some baby cedars that didn’t make it (not much root growth through the pot, so I figured it wasn’t spent). At this point I figured that, like almost any other plant, it would be easy to burn the babies, so it’s just water and I’m actually just bottom-watering instead of pouring from over the top of the plant. They seem to be happy.
As for the Botanicare, that appears to be a product for hydroponic gardening. Will it translate to outdoor potted grows?
I like using organic myself, which is why I went for the composted stuff and we’ve set up a compost heap on the property. However, our compost is new and hasn’t quite yet gotten going.
That’s an interesting watering technique. I suppose as long as it wicked sufficiently it would eliminate dry spots from water “channeling” through the soil.
The Pro Grow is for both hydro and soil, and the bloom is actually designed for soil or only the last few weeks of a hydro grow. I use it in organic soil / perlite / dolomite lime / pinch of guano mix that seems to work pretty well. I go easy on the guano until I’m transplanting into larger pots as it is a bit much for seedlings. I keep hearing about Fox Farm nutrients, but have no experience. I guess I would do some web-crawling to get some clues for what might work for you.
I’ve heard great things about fresh compost. Because its mild, you can more exactly tailor the flavor of your soil. Someday past apartment living this will be a reality for me.
Hello I did use the search … chances are though I didn't correctly word it. I want to know when to fertilize seedling or my new plants. How old or how…