’At the beginning of April, I’m gradually starting my seedlings. In mid-March, I planted some verbena bonariensis. Although I don’t have many seedlings to start at once, this gives me time to get everything I need and ease into the process. ‘At the beginning of April, I’m gradually starting my seedlings. In mid-March, I planted some verbena bonariensis. Although I don’t have many seedlings to start at once, this gives me time to get everything I need and ease into the process. Photo : Mathieu Hodgson.
I planted kale, parsley, dill, and, of course, tomatoes, which are the star of the vegetable garden, at the beginning of April. It’s getting crowded in here, but the work isn’t done yet! This week I’m starting lettuce seedlings that I will move to the garden in early May for my first harvest. The last ones to come, indoors, will be cucumbers and nasturtiums, in early May.
I’ve only seen a small head of vervain come up from the soil so far, but soon there will be seedlings coming up everywhere, like in whack-a-mole (don’t worry, I won’t hit my seedlings with a hammer!). We don’t have much space in our home for seedlings. Under my desk is a shelf with two seedling trays. One is covered with a clear plastic dome where I keep my pots before germination. The other is not covered and I use it to transfer seedlings that have germinated. The whole thing is overhung with a full-spectrum LED light. Eventually, all those seedlings will get hungry! How to feed them?.
I’ll tell you a secret. Last year, I completely forgot to fertilize my seedlings. Even though there were a few failures (every year, some plants do better than others), my garden did so well that I didn’t even notice.
Don’t get me wrong, I’m not suggesting you stop using fertilizers on your seedlings. This year, I won’t forget to do it, I swear. There is, however, one thing I believe we need to know about fertilizing in order to do it properly: why and how. Photo :
Starting plants from seeds can be an incredibly rewarding experience. Watching those tiny seeds sprout and grow into robust seedlings ready for transplanting is amazing However, getting your seedlings off to a strong start requires providing them with the right nutrients early on Finding the best fertilizer for seedlings can seem confusing with so many options available. In this article, we’ll walk through everything you need to know to choose the ideal plant food to help your seedlings thrive.
Why Fertilizing Seedlings is Important
While seeds contain enough stored nutrients to support initial germination and growth, these resources are limited Within a few weeks of sprouting, young seedlings will have exhausted the food supply in their seed. Without additional nutrients provided by fertilizer, seedlings can become stunted and experience deficiencies Fertilizing gives them the nitrogen, phosphorus, and potassium they need to develop strong roots and leaves. This sets them up for vigorous growth when transplanted into your vegetable garden or flower beds.
When to Start Fertilizing
Most experts recommend beginning to fertilize seedlings when the first true leaves emerge. This is generally around 2-4 weeks after sowing, depending on the plant variety. Watch for the first set of leaves that resemble the mature leaves of the plant. Prior to this, the baby seed leaves (cotyledons) provide nourishment. Once true foliage is present, it’s time to supplement with plant food. Continue providing fertilizer regularly as the seedlings grow.
What to Look for in a Seedling Fertilizer
When purchasing fertilizer for seedlings, read the label to ensure it contains the right ratio of key nutrients:
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Nitrogen (N) promotes lush green growth and strong stems and leaves,
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Phosphorus (P) aids in root system development and flower/fruit production.
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Potassium (K) (also called potash) assists with overall plant health.
An all-purpose fertilizer with relatively equal amounts of N-P-K is ideal for seedlings. The numbers on the label represent the percentages of each nutrient. A 10-10-10 or 20-20-20 fertilizer provides a balanced diet. You can also look for something labeled specifically for seedlings. Avoid “bloom booster” formulas with very high potassium or phosphorus levels. Too much of these can inhibit healthy leaf growth.
Types of Fertilizers for Seedlings
There are many options available when choosing a plant food for seedlings:
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Liquid fertilizers – These soluble concentrated formulas are mixed with water and applied by watering seedlings. Liquid options allow precise control over nutrient levels. Look for a mild liquid fertilizer to avoid burning young plants with excess nutrients.
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Granular fertilizers – Granular forms are stirred into the potting mix prior to sowing seeds. The nutrients slowly release as the seedlings grow. This provides a gentle, steady fertilization method.
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Compost teas – Compost teas provide organic nutrients and beneficial microbes. Sprinkle diluted compost tea on seedlings or add it to their water.
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Time-release pellets – Slow release pellets mixed into the soil offer long-term, low concentration feeding. These are easy to apply at planting.
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Powdered fertilizers – Powder forms are simply sprinkled lightly over the soil surface. They break down quickly with watering to deliver fast-acting nutrition. Use sparingly on seedlings.
Experiment to see which method works best for your particular plants and preferences. Liquid fertilizers tend to give the most control over nutrient levels.
How Much Fertilizer Do Seedlings Need?
Seedlings are sensitive and require diluted fertilizer strengths compared to mature plants. Follow label directions to mix liquid feeds at one quarter or less of the recommended rate. For example, if instructions say to mix 1 tbsp per gallon for established plants, use 1⁄4 tbsp per gallon for seedlings. You can gradually increase the concentration over time as plants grow stronger. With granular, time-release, and powder feeds, use very small amounts. It’s best to slightly under-fertilize rather than overload young seedlings.
Are There Signs of Nutrient Deficiencies?
Keep an eye out for signals that your seedlings need more fertilizer. If you see any of these signs, increase the feed strength slightly:
- Pale or yellowing leaves
- Stunted growth
- Weak, thin stems
- Lack of new leaves
- Tip burn or necrotic spotting – a sign of excess nutrients. Reduce fertilizer if this occurs.
Vibrant deep green leaves, vigorous growth, and strong stems indicate your fertilization program is working well! Adjust amounts and timing based on the condition of your particular seedlings.
What is the Best Fertilization Schedule?
Fertilizing seedlings is a balance between providing adequate nutrition and avoiding excess salts that can burn delicate roots and leaves. Some general guidelines include:
- Fertilize weekly or with every second watering. More frequent feeding is usually better than heavy doses at longer intervals.
- Alternate between plain pH-balanced water and fertilizer solution to flush any buildup.
- Mix liquid feeds fresh each time rather than storing premixed batches.
- Give granular and time-release feeds only once near the beginning. Powdered feeds can be reapplied lightly every couple of weeks.
- Reduce frequency as seedlings harden off prior to transplanting.
Customize the regimen to suit your specific seedlings based on their condition. Ramp down feeding if you observe fertilizer burn. Increase frequency if plants show nutrient deficiency signs. Finding the ideal program through experience will give your seedlings a strong head start.
Ready to Pick the Best Fertilizer for Your Seedlings?
With a basic understanding of seedling nutritional needs, you can now confidently choose a fertilizer to start your seeds off right. Look for balanced all-purpose plant foods designed specifically for seedlings. Whether you select liquids, granular, powders, or time-release forms, be sure to use diluted strengths to prevent burning these tender young plants. Begin fertilizing as soon as true leaves emerge, and continue on a weekly or biweekly schedule. Adjust amounts based on the condition of your seedlings. Providing just the right amount of fertilizer will set your seedlings up for transplanting success into the garden!
So What Do We Use as Fertilizer?
When you’re a laidback gardener, you work as little as possible. I rarely use water-soluble fertilizers because I have to add them regularly and it’s too much work. This is why I use an all-purpose, slow-release organic fertilizer that will let its minerals out over the course of a whole season. But for seedlings, I make an exception. So I use an organic fertilizer that dissolves in water and add it every time I water. I want them to get nutrients right away, not at the end of the year! However, you can use a quarter or half of the manufacturer’s recommended dose.
Fertilizer labels have numbers that show how much nitrogen (N), phosphorus (P), and potassium (K) the plant needs to live. I don’t pay too much attention to these numbers. Plants will take what they need. That’s why I use all-purpose fertilizer. But if I had a fertilizer for annual plants on hand, I wouldn’t throw it in the garbage. It might as well serve a purpose.
But, be careful with fertilizers with very high numbers (like 30-30-30 ), as they may damage your seedlings. If you notice leaves with brown tips, stop or slow down your fertilization. It is possible that the fertilizer has built up in the soil and is now too concentrated.
For years, my father used liquid seaweed fertilizers, such as Bionik Liquid Seaweed 0.36-0-0.22. But there is a new product available on the market that I will try this year and that contains not only seaweed, but also insect frass: Bionik All Purpose Fertilizer 1-0.5-0.3. This fertilizer, certified organic by Québec Vrai is also a product of Québec. Its main ingredient, insect frass, is a residue from insect breeding containing their droppings and molts. Studies have shown that frass has the ability to increase plant growth and yield. In the garden, the chitin contained in this product from insect molts will feed the microscopic fauna of your soil, which un turn will help prevent diseases and pest infestations. Available soon in a garden center near you!
When to Start Fertilizing Your Seedlings?
Many people have told me the same story, but most agree that fertilization should start when the seedling has four to six true leaves. When I say “true leaves,” I don’t mean the cotyledons, which are the plant’s first two leaves and look different from the other leaves. In truth, the cotyledons are already inside the seed before germination and unfold when the conditions are right.
Now is the time! Why wait until the plant has four to six leaves? It’s easy! People who eat pumpkin or sunflower seeds know how full of energy they are. So, a seed has a small embryonic plant inside it, as well as a lot of energy to help the seedlings grow until they have roots to feed themselves and leaves to do photosynthesis. No leaves, no roots, no fertilizer!.
It is also important to note that many potting soils are lightly fertilized. Check the packaging of your favorite potting soil. This might explain why my seedlings last year did well despite the lack of fertilizer. Another reason to wait until our seedlings are developed before fertilizing. Photo : Mathieu Hodgson.
What is the Best Fertilizer for Seedlings?
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