How to fertilise seedlings and young veggies without burning them
Feed seedlings with a half-strength liquid fertiliser (about 1.25 mL per litre of water) once they have their first true leaves, then weekly at that gentle rate until planting out. After transplanting, wait a week, then move to the normal 2.5 mL per litre rate fortnightly. Seedlings burn easily; dilute liquid feeding is the safe way, and granular fertiliser near young roots is the fast way to lose a punnet.
Spring seed-raising season is here, and the difference between leggy, stalled seedlings and stocky green ones is mostly food and light. Here is the gentle routine.
When to start feeding
Seeds carry their own lunchbox: the first pair of leaves (cotyledons) run on stored energy, and seed-raising mix is deliberately low in nutrients. Start feeding when the first true leaves appear, the ones that look like the adult plant. Feeding earlier does nothing useful; feeding never is why seedlings sit still for weeks.
How to feed without burning
- Half strength: 1.25 mL of Medigrow per litre, weekly. Young roots are fine and shallow, and dilute-and-often is the rule.
- Water first if dry: never feed into a bone-dry punnet.
- Gentle delivery: a fine rose on the can, or a light foliar mist, which tiny root systems appreciate.
- Light to match: feeding without strong light makes seedlings leggy. A bright, sunny position keeps them stocky.
Transplanting and stepping up
Skip feeding for about a week after planting out while roots settle, then move to the standard rate: 2.5 mL per litre, every 1 to 2 weeks. Leafy crops (lettuce, spinach, silverbeet, herbs) stay on this nitrogen-led feed for their whole life. Fruiting crops (tomatoes, cucumbers, zucchini, chillies) switch to a bloom feed at first flowers; the changeover is covered in when to switch from grow to bloom, and tomatoes get their own full guide.
Signs to read
Pale, slow, thin: hungry; feed weekly and check light. Crispy edges or white crust on the mix: overfed; flush with plain water and drop the strength. Purple-tinged leaves in cold weather: phosphorus is hard to take up in cold soil; it self-corrects as soil warms, so do not panic-feed.
Common questions
Can I use the same bottle for seedlings and the rest of the garden?
Yes, just change the dose. Half strength for seedlings, full strength for everything else. One concentrate covers the punnets, the veggie bed and the lawn, which is the point of a 1 L bottle making 400 L of feed.
How often is too often?
Weekly at half strength is the ceiling for seedlings. Daily feeding builds up salts in a small cell of mix faster than roots can use them.
What about native seedlings?
Feed even more gently: quarter to half strength, monthly. Many natives prefer lean conditions, especially on phosphorus.
Put it into practice
Medigrow builds growth, Medibud brings the bloom. The bundle covers the whole season from 38c a feed, backed by the 30-Day Growers Guarantee.
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