Fertilizing Seedlings

When Feeding is NOT Needed (or Should Be Postponed):

You can safely forget about feeding during the first 2–3 weeks of your seedlings' life if:

1. You are using a specialized commercial seedling mix. Quality producers (e.g., based on peat) initially enrich their mixes with a starter dose of mineral fertilizers. This supply is sufficient until the 2–3 true-leaf stage (Vendilo et al., 1989).

2. You have prepared a nutrient-rich mix with compost and wood ash yourself, and the container is large enough for the roots to explore the entire volume.

Why does this work? A tomato seed contains enough nutrients to support germination and the unfurling of the first cotyledon leaves. Then the roots take over. If the soil contains readily available nitrogen, phosphorus, and potassium, the plant uses them without stress. Overfeeding at this stage is not only useless but dangerous: it can burn tender roots or trigger excessively rapid, leggy growth (etiolation) at the expense of root development.

When Feeding is MANDATORY:

There are situations where you simply cannot get strong, healthy seedlings without additional nutrition.

1. Poor, infertile substrate. If you're using garden soil that hasn't been fertilized for years, or cheap "all-purpose" mix consisting mostly of lowland peat and sand. Such substrates contain almost no available phosphorus or potassium.

2. Signs of starvation. If you notice lower leaves turning pale, yellowing, slowed growth, and thinning stems — this is a clear signal of nutrient deficiency (Akhatov, 2010). We'll discuss how to recognize specific deficiencies in a separate chapter.

3. Extended stay in a small container. If you've delayed transplanting or potting up, the roots may have filled the entire root ball, depleting nutrients faster than expected.

Why should a gardener understand this? Knowing these two scenarios helps avoid the main mistake — "feeding just in case." More often than not, seedlings suffer not from hunger but from overfeeding, which leads to excessive vegetative growth ("fattening") and reduced disease resistance. Our goal is not to grow a huge bush, but to build a solid foundation for future yields.

To summarize:

• General rule: Before transplanting (at the 2–3 true-leaf stage), no feeding is needed if you're using a commercial mix.
• Exception: The first feeding (a weak solution of a complete fertilizer) is warranted if seedlings are growing slowly in initially "empty" soil. This typically happens at the 1–2 true-leaf stage.

Next, we'll break down exact timing so you can confidently identify the "X" moment for your seedlings.

The Golden Rule: The True-Leaf Stage

The timing of the first feeding is directly linked to the plant's transition from "cotyledon" nutrition to "root" nutrition.

• Cotyledon stage (from emergence to the first true leaf): During this period, the seedling lives on reserves stored in the seed and minimal resources absorbed through its still-weak root system (Akhatov, 2010). Any fertilizer at this stage risks burning the roots.
• 1–2 true-leaf stage: The plant begins actively developing its root system. In quality commercial mixes, there are enough nutrients to last until transplanting (Vendilo et al., 1989).
• 2–3 true-leaf stage (or 7–10 days after transplanting): This is the optimal window for the first feeding in 95% of cases.

Why this moment? After transplanting, roots get new space but are inevitably damaged. During the first week, the plant recovers and begins to grow new feeder roots. About 7–10 days later, when the seedlings start growing again, they experience an increased need for phosphorus (for root development) and nitrogen (for leaf growth). Applying fertilizer at this time gives a powerful boost to development (Swiader, 1992).

Exceptions (When You Can Feed Earlier)

There are two situations where the first feeding is done BEFORE transplanting, but not before the first true-leaf stage:

1. High-quality seeds + poor substrate. If you sowed seeds in poor soil (e.g., old garden soil) and see growth stall at the 1–2 leaf stage with weak-looking stems, you can apply a very weak foliar spray or a minimal dose of a complete fertilizer with an emphasis on phosphorus (Swiader, 1992). This stimulates root formation.

2. Delayed transplanting. If seedlings have become overgrown, transplanting is postponed, and they are starting to stretch due to crowding, a potassium-rich feed will help strengthen tissues and relieve stress.

But remember: for standard seedlings in good soil, the first feeding is done ONLY AFTER TRANSPLANTING, once the plants have rooted.

A Practical Guide for the Gardener

You sowed seeds in a commercial seedling mix.

• Action: Do not feed until 2–3 true leaves appear (roughly 10–14 days after emergence). Then transplant. Only 7–10 days after transplanting, give the first full feeding.

You sowed seeds in poor, "lean" soil.

• Action: At the 1–2 true-leaf stage, you can apply one foliar feeding (spraying) with a weak solution of complete fertilizer (e.g., 0.1% solution) to support the plant. However, the main feeding will still be after transplanting.

Why does this matter? Following this rule ensures you don't harm the plant during its most vulnerable period (the seedling stage) and provide nutrition precisely when it is ready to absorb it. This is the foundation for a healthy start.

Main Feeding Table

In this table, we use nitrogen (N) for green growth, phosphorus (P) for root development and flower cluster formation, and potassium (K) for strengthening tissues, boosting immunity, and improving fruit quality.

Explanations for the Table

1. Why should the first feeding contain phosphorus?

Phosphorus is the "energy" of the root. It stimulates root branching, helping the plant quickly explore the new soil volume after transplanting (Balashev & Zeman, 1981). Without sufficient phosphorus, roots grow slowly, and the entire plant lags in development.

2. Why is potassium needed in the second and third feedings?

Potassium performs many vital functions. It strengthens cell walls (making stems sturdy), increases resistance to diseases and drought, and — most importantly — participates in the formation of flower clusters. High potassium at this stage is the key to ensuring your plant invests its energy in future fruit rather than "fattening" (excessive green growth) (Akhatov, 2010).

3. Why add calcium nitrate before planting out?

Calcium is the "building material" for cell walls. Calcium nitrate provides both nitrogen (in nitrate form, easily absorbed) and calcium. This prevents blossom-end rot when fruits begin to set (Swiader, 1992). Many gardeners overlook this and later wonder why dark spots appear on the lower fruits.

4. Why is foliar feeding (on leaves) faster?

Tomato leaves, especially on the underside, are covered with many stomata. They can absorb nutrients hundreds of times faster than roots. So if you see your plant "starving" (yellowing, paleness), spraying with a weak fertilizer solution is emergency first aid (Swiader, 1992).

What is NPK and Why Should You Know It?

On any fertilizer package, you'll see three numbers, e.g., 15-15-15 or 13-16-13. These represent the percentage of three main elements:

• N (Nitrogen) — responsible for green growth (leaves and stems).
• P (Phosphorus) — stimulates root system development and flower cluster formation.
• K (Potassium) — strengthens tissues, boosts immunity, and improves fruit quality.

Understanding these numbers allows you to choose the right fertilizer for each growth stage.

1. Complete NPK Fertilizers (for Seedlings)

These are the "universal soldiers" containing all three main elements in a balanced ratio. They are ideal for the first feeding after transplanting, when the plant needs a full range of nutrients for a strong start.

When to use: 7–10 days after transplanting (2–3 true-leaf stage).

What to choose: Look for formulas with slightly higher phosphorus, such as N-P-K 13-16-13 or 15-15-15. This stimulates root development while nitrogen supports leaf growth (Swiader, 1992).

How to use:

• Dissolve 0.5–1 g of fertilizer in 1 liter of water (or strictly follow the label).
• Water at the base, avoiding leaves.

Why it works: Balanced nutrition during this critical period helps the plant recover quickly from transplanting and start actively building root and leaf mass (Akhatov, 2010).

2. Monopotassium Phosphate (P-K 0-52-34)

This is a concentrated fertilizer high in phosphorus and potassium with zero nitrogen. It's your main tool for the second and third feedings.

When to use: 2 weeks after the first feeding (4–6 true-leaf stage) and 7–10 days before planting out.

Why it's needed: Phosphorus and potassium are more important than nitrogen at this stage. They:

• Strengthen the stem — seedlings become stocky and don't stretch.
• Stimulate flower cluster formation — the future harvest is being set right now.
• Increase stress resistance — to temperature fluctuations, drought, and diseases (Balashev & Zeman, 1981).

How to use:

• Dissolve 0.8–1.5 g of monopotassium phosphate in 1 liter of water.
• Foliar (on leaves): Spray the undersides of leaves. This is the fastest way to deliver elements to tissues.
• Root: Water at the base.

Important: Monopotassium phosphate can be used for both foliar and root feeding. It's a versatile product (Akhatov, 2010).

3. Calcium Nitrate (N-Ca 15.5-0-0 + 19% CaO)

This fertilizer contains nitrogen (in nitrate form) and calcium. Calcium is the "building material" for cell walls. Its deficiency leads to blossom-end rot — a disorder where dark, sunken spots appear on the bottom of tomatoes (Swiader, 1992).

When to use: 7–10 days before planting out (along with monopotassium phosphate).

Why just before planting out:

• Prevents blossom-end rot. Calcium stored in tissues will protect the first fruit sets.
• Nitrate nitrogen is easily absorbed and gives the plant energy to adapt to new conditions.

How to use:

• Dissolve 0.5–1 g of calcium nitrate in 1 liter of water.
• Water at the base or spray on leaves.

Why it matters: Many gardeners neglect calcium and then wonder why their first tomatoes are spoiled. Calcium nitrate is a simple, effective solution (Swiader, 1992).

4. Specialized Complete Fertilizers for Seedlings

You can find fertilizers labeled "for seedlings" or "starter" formulas. They have a specially balanced composition with higher phosphorus and micronutrients (iron, zinc, copper, manganese) in chelated (readily available) form.

When to use: At all stages, if you prefer not to mix different fertilizers yourself.

Advantages:

• Already contain all necessary micronutrients.
• Easy to dissolve.
• Clear instructions.

Disadvantage: More expensive than simple fertilizers (e.g., monopotassium phosphate and calcium nitrate).

How to choose: Look for formulas like N-P-K 15-15-15 or those with higher phosphorus/potassium for later stages. Follow the package instructions.

Summary Table: What and When to Use

General Rules for Applying Mineral Fertilizers

1. Don't exceed the dosage. Better to underfeed than overfeed. Excess salts burn roots and inhibit growth.

2. Dissolve in warm water (20–25°C). Cold water dissolves fertilizers poorly; hot water may degrade them.

3. Apply root feedings to moist soil. First water with plain water, then 2–3 hours later apply the fertilizer solution. This prevents root burn.

4. Apply foliar feedings in the morning or evening. Spraying leaves on a sunny day can cause burns.

The Main Principle: For Seedlings, Organics Are "Slow Fuel"

The fundamental difference between organics and mineral fertilizers is that plants absorb only mineral ions (nitrates, phosphates, potassium cations, etc.). Organic materials (compost, manure, humus) are complex compounds that must first be broken down by soil microorganisms (Vendilo et al., 1989). Only then do minerals become available to roots.

In the small volume of a seedling pot, this process is slow and unpredictable. Moreover, undecomposed organics can:

• Cause toxicity: release ammonia that burns tender roots (Akhatov, 2010).
• Trigger diseases: become a breeding ground for pathogenic fungi and bacteria.
• Attract pests: such as fungus gnats (sciarids).

Therefore, for seedlings, organic feeding is a supplementary, not primary, tool.

When and Which Organics CAN Be Used?

Practical Recommendations

1. Best option: Use quality vermicompost as a soil base. It improves structure, making it loose and aerated, and provides a starter supply of micronutrients and humic acids (Mattoo, 2017).

2. For early feedings: Forget liquid organic feeds. During the active growth phase of roots and leaves, the plant needs precise doses of nitrogen, phosphorus, and potassium. These are easier and safer to provide with mineral fertilizers.

3. Biostimulants: Liquid vermicompost, humic acids, and seaweed extracts (e.g., from kelp) are not so much "food" as "stimulants." They help the plant better absorb mineral nutrients and tolerate stress (transplanting, repotting). They can be used alongside mineral feedings (Akhatov, 2010).

4. The golden rule: If you choose organics for seedlings, prefer ready-made, commercially produced preparations (liquid vermicompost, seaweed extracts). They have standardized composition, are pathogen-free, and won't cause burns if used at the correct dosage.

An Alternative Perspective

In professional vegetable growing, organic feedings are rarely used for seedlings. The reasons are simple: high cost, variable composition, and contamination risk. To achieve guaranteed results in a short time, mineral fertilizers are used (Swiader, 1992). Organics belong in the open ground, where microorganisms and earthworms can "digest" them into plant-available forms.

Conclusion for the home gardener:

• Organics are excellent "building materials" for improving soil.
• For feeding seedlings, it's preferable to use specialized liquid organic preparations (vermicompost, potassium humate) in small doses, as a supplement to the main mineral program.
• If you decide to use manure or poultry tea, do so only for mature plants in the ground, not for tender seedlings in pots.

How to Tell Deficiency from Disease or Stress?

Before reaching for fertilizers, rule out other factors:

• Overwatering or drying out — roots suffocate or cannot absorb water, leaves wilt and yellow.
• Low temperature (below +15°C) — roots stop working, and even with nutrients present, the plant starves.
• Diseases — often cause spots, rot, or coatings that are not present with pure nutrient deficiency.

If conditions are normal but seedlings look stressed, it's likely a nutrition issue. The table below will help you "diagnose" the problem.

Table: Symptoms, Causes, and Solutions for Deficiencies

Important Notes on the Table

1. Deficiencies rarely come alone. Symptoms often overlap. For example, nitrogen deficiency weakens the plant, making it harder to absorb other elements. So if you see multiple symptoms, start with a balanced complete fertilizer, then fine-tune.

2. Foliar feeding (spraying leaves) is the fastest method. Micronutrients (iron, boron, zinc) and magnesium are absorbed several times faster through leaves than through roots. For nitrogen, phosphorus, and potassium, foliar feeding is also effective but is more of "emergency aid" than primary nutrition.

3. Before applying any fertilizer, check soil pH. In acidic soils (pH < 5.5), calcium, magnesium, and phosphorus are poorly absorbed. In alkaline soils (pH > 7.5), iron, boron, zinc, and copper are locked out. Adjust pH with dolomite lime (for acidic) or peat/gypsum (for alkaline) — this can solve many problems without extra feeding (Vendilo et al., 1989).

4. Don't confuse calcium deficiency with blossom-end rot. Blossom-end rot is an external symptom of calcium deficiency, but it can occur even when calcium is sufficient in the soil if the plant is stressed by uneven watering or high temperatures — calcium simply doesn't reach the fruits. Prevention: regular watering and maintaining humidity.

Visual Guide: What to Check First

• Lower leaves → issues with nitrogen, phosphorus, potassium, magnesium (mobile elements).
• Upper leaves and growing tip → issues with calcium, iron, boron (immobile elements).
• Leaf edges → most often potassium.
• Green veins with yellow between them → magnesium (lower leaves) or iron (upper leaves).

Takeaway for the gardener:

Inspect your seedlings regularly. Compare lower and upper leaves. If you see deviations, consult the table. Start by adjusting watering and temperature, then apply targeted feedings. Remember: treating a deficiency is easier than treating overfeeding — excess fertilizer is often more dangerous than deficiency.

Days 0–3: "Quarantine" and Adaptation

Immediately after transplanting, seedlings enter a critical period. The main rules:

1. Water generously with warm water. After transplanting, the root ball should be well moistened. Water should be 2–3°C warmer than room temperature (about 25–28°C). Warm water stimulates root activity and speeds establishment (Akhatov, 2010).

2. Shade. For the first 2–3 days after transplanting, keep seedlings out of direct sunlight. Place them on a north-facing windowsill or cover with paper, cloth, or a shading net. Bright light increases moisture loss through leaves, while damaged roots can't yet compensate. This can lead to wilting (Swiader, 1992).

3. Higher humidity. If possible, mist the air around the seedlings with a sprayer or cover them with a transparent dome (cut plastic bottle, plastic wrap) for 1–2 days. This creates a "greenhouse effect" that reduces leaf evaporation and helps the plant tolerate root damage (Swiader, 1992).

4. No feeding! For the first 5–7 days after transplanting, do not apply fertilizers. Roots are injured and cannot absorb nutrients effectively. Moreover, fresh soil already contains a starter supply of nutrients (Vendilo et al., 1989). Applying fertilizer at this stage can cause chemical root burn.

Why this works? After transplanting, the plant's main task is to restore root integrity. It uses internal reserves — carbohydrates and amino acids stored in stems and leaves. Feeding at this stage won't help; it will only divert energy toward salt uptake when that energy is needed for regeneration. Shading and higher humidity reduce evaporation, allowing the plant to focus on growing new roots rather than combating dehydration.

Days 4–7: First Signs of Life

At this stage, you'll see that the seedlings have "come alive": leaves have perked up, and new growth appears. This signals that roots have started working.

1. Gradually introduce light. Begin removing the shade, increasing sun exposure slowly. Start with 1–2 hours in the morning or evening, then half a day, and finally a full day. This is a hardening process (adaptation to bright light). Removing shade abruptly can cause sunburn on tender leaves (Akhatov, 2010).

2. First watering with a biostimulant (optional). If you want to speed up adaptation, water with a root-stimulating solution — e.g., based on humic acids, succinic acid, or products containing indolebutyric acid (IBA). These stimulate new root formation.

Days 7–10: Active Growth Begins

This is the key moment for transitioning to active care. The seedlings have fully adapted, and roots are actively exploring the new soil volume.

1. First feeding. Right now, 7–10 days after transplanting, we apply the first full root feeding (see Chapter 3, Table 1). Use a complete seedling fertilizer with an emphasis on phosphorus (N-P-K roughly 15-15-15 or 13-16-13). This gives a powerful boost to root development and green growth (Balashev & Zeman, 1981).

2. Water regularly. At this stage, seedlings start drinking actively. Don't let the root ball dry out, but don't overwater either. Check the topsoil: if it's dry to 0.5–1 cm deep, it's time to water.

3. Ventilate. If you used a greenhouse effect (dome, plastic), remove the cover by day 10. Plants must adapt to normal humidity.

Day 14 and Beyond: Regular Care

Now your job is to maintain stable conditions for active growth.

1. Subsequent feedings. The second feeding is 2 weeks after the first (usually at the 4–6 true-leaf stage) with a high-phosphorus, high-potassium fertilizer (monopotassium phosphate). The third is 7–10 days before planting out in the open ground (see the full schedule in Chapter 3).

2. Regular watering. Maintain steady soil moisture. Avoid sudden fluctuations — they can cause stem cracking (Swiader, 1992).

3. Temperature regime. After transplanting, optimal daytime temperature is 20–22°C, nighttime 16–18°C. Higher temperatures (above 25°C) combined with insufficient light will cause seedlings to stretch (Akhatov, 2010).

4. Hardening off. 10–14 days before planting out, start gradual hardening: take seedlings outdoors (balcony, greenhouse) for a few hours first, then a full day, and finally overnight (if no frost risk). This strengthens cell walls and increases resistance to temperature swings and wind (Swiader, 1992).

What NOT to Do

• Don't overwater. The most common mistake after transplanting is overwatering. Water displaces air from the soil, roots suffocate and rot (root rot).
• Don't feed too early. Remember: first feeding is only 7–10 days after transplanting.
• Don't put directly in the sun. Shading is mandatory for the first few days.
• Don't use cold water. Cold water stresses and shocks the roots.

Summary

Now we have a complete picture: from "do I need to feed" to "what to do after transplanting." One final chapter remains — "8. Common Mistakes." This concluding section will help gardeners avoid the most frequent pitfalls. Ready to write it?

Mistake 1: Feeding Immediately After Transplanting

What happens: The gardener, wanting to help seedlings "settle in," applies fertilizer right after transplanting into individual pots.

Why it's harmful: Roots are damaged and cannot absorb nutrients. Moreover, fresh soil already contains a starter supply of nutrition. Applying fertilizer at this stage burns roots and slows their regeneration (Vendilo et al., 1989; Akhatov, 2010).

How to avoid: The first feeding is done only 7–10 days after transplanting, once the plants have rooted and resumed growth.

Mistake 2: Using High Doses "Just to Be Safe"

What happens: The gardener thinks, "more is better," and exceeds the recommended dosage by 2–3 times.

Why it's harmful: Excess salts in the soil raise osmotic pressure. Roots cannot absorb water, and the plant begins to "burn" — leaf edges yellow and dry. This condition is called physiological drought (Akhatov, 2010). Excess nitrogen is especially dangerous: it triggers lush green growth ("fattening") at the expense of roots and flower cluster formation (Balashev & Zeman, 1981).

How to avoid: Strictly follow dosages on fertilizer labels and in our table (Chapter 3). Better to give slightly less than more. For seedlings, always use a concentration half as strong as for mature plants.

Mistake 3: Feeding Only with Nitrogen Fertilizers

What happens: The gardener uses only urea, ammonium nitrate, or nettle tea, ignoring phosphorus and potassium.

Why it's harmful: Nitrogen stimulates leaf and stem growth, but without phosphorus, roots will be weak, and without potassium, stems will be thin and brittle, and disease resistance will drop. The seedlings will "fatten," and flower clusters will set late and weakly (Swiader, 1992).

How to avoid: Use balanced complete fertilizers with macroelements (N, P, K) in different ratios at different stages (see Chapter 3). Don't rely on nitrogen alone.

Mistake 4: Feeding on Dry Soil

What happens: Fertilizer (especially dry granular) is applied to dry soil, then watered.

Why it's harmful: Salt concentration around the roots spikes sharply, causing chemical burns. The roots experience "shock" and stop functioning.

How to avoid: Always apply feeding on moist soil. 1–2 hours before fertilizing, water with plain water. This distributes the solution evenly and keeps concentrations safe.

Mistake 5: Ignoring Foliar Feedings

What happens: The gardener relies only on root feedings (watering at the base).

Why it's a missed opportunity: Sometimes roots cannot work effectively (e.g., in cold soil or after transplanting). Foliar feeding (on leaves) allows nutrients to enter the plant hundreds of times faster, bypassing the root system. It's an effective way to quickly correct micronutrient deficiencies or relieve stress (Swiader, 1992; Akhatov, 2010).

How to avoid: Include foliar feedings in your schedule, especially during post-transplant adaptation or at the first signs of deficiency (pale leaves). Use weak solutions (0.1–0.2%) and spray the undersides of leaves, where stomata are more numerous.

Mistake 6: Using "Homemade" Organic Teas (Manure, Poultry, Grass)

What happens: The gardener waters seedlings with manure or nettle tea, thinking it's "natural and safe."

Why it's harmful: Such teas contain high ammonia nitrogen, which is toxic to tender root systems. They may also harbor pathogens and weed seeds. In a small pot, fermentation can overheat and kill roots (Mattoo, 2017).

How to avoid: For seedlings, use only commercially produced organic preparations (liquid vermicompost, seaweed extracts, humic acids). They are safe, standardized, and pathogen-free. Save manure and poultry teas for mature plants in the open ground.

Mistake 7: Feeding at the Cotyledon Stage

What happens: The gardener starts feeding seedlings right after emergence, thinking they need nutrition.

Why it's harmful: At the cotyledon stage, the plant lives on seed reserves and does not need external fertilizers. Besides, the root system is too weak to absorb salts. Feeding can cause burns (Akhatov, 2010).

How to avoid: The first feeding is done no earlier than 7–10 days after transplanting (at the 2–3 true-leaf stage). Before that, only clean water as needed.

Mistake 8: Neglecting Micronutrients

What happens: The gardener applies only nitrogen, phosphorus, and potassium (NPK), forgetting about iron, boron, zinc, manganese.

Why it's harmful: Micronutrient deficiencies cause characteristic symptoms: chlorosis (yellowing) of young leaves (iron deficiency), growing tip death (boron deficiency), mottling (zinc deficiency) — see the table in Chapter 6. Without micronutrients, the plant cannot fully utilize macronutrients (Akhatov, 2010).

How to avoid: Use complete fertilizers that contain micronutrients in chelated form (readily available). This is usually stated on the label. Or periodically apply foliar sprays with specialized micronutrient preparations.

Mistake 9: Stopping Feedings 2–3 Weeks Before Planting Out

What happens: Some gardeners believe stopping feedings 2–3 weeks before planting out "hardens" the seedlings.

Why it's a mistake: 2–3 weeks before planting out, the plant is actively setting flower clusters. At this stage, it especially needs phosphorus and potassium. Stopping feedings depletes the plant, leading to poor flowering and reduced yields (Swiader, 1992).

How to avoid: Continue feeding until planting out, but 7–10 days before planting, increase the proportion of potassium and phosphorus (monopotassium phosphate) and reduce nitrogen. This strengthens tissues and helps the plant survive transplanting.

Summary: 10 Commandments of Seedling Feeding

1. Don't rush — the first feeding is only 7–10 days after transplanting.

2. Less is better — always use half the dose recommended for mature plants.

3. Never feed on dry soil.

4. Balance NPK — don't forget phosphorus and potassium.

5. Include micronutrients (iron, boron, zinc).

6. Use foliar feedings — they work faster.

7. Avoid aggressive organics (manure, poultry) for seedlings.

8. Stop feedings 7–10 days before planting out? — No! Continue, but emphasize potassium and phosphorus.

9. Watch the plant's response — yellowing, curling, spots are signals to adjust (see Chapter 6).

10. Remember: healthy, hardened seedlings are the result of not just feeding, but also proper light, temperature, and watering.