The first 3 weeks of your plant | Highbreed Seeds

The first 3 weeks of your plant

Your seed has germinated and the radicle is already showing: congratulations, you have got past the most delicate step. But the first three weeks are still critical. At this stage the seedling is fragile and the most common mistake is overdoing the care. The golden rule: less is more.


🌱 Week 1: from sprout to cotyledons


As soon as the radicle is 1-2 cm long, move it to the substrate (if you germinated in paper or water), root facing down and 0.5-1 cm deep. Within a few days you will see the cotyledons (the first two rounded leaves).

  • Watering: minimal. Mist or water very lightly around the stem; the substrate should only be damp.
  • Ambient humidity: high (65-70%) so the seedling doesn't get stressed.
  • Light: gentle and not too close. Too much direct light burns a seedling that doesn't yet have the roots to keep up.


🌿 Week 2: first true leaves


The first pair of true leaves (already serrated) appears and the plant starts to photosynthesise properly.

  • Watering: still light, but let the top layer of substrate dry out between waterings. This forces the root to search and grow.
  • Light: you can bring it a little closer; watch that it doesn't stretch (too little light) or scorch (too much).
  • Nutrients: not yet. A good substrate has enough reserves for these weeks.


🍃 Week 3: growth takes off


The roots are now more developed and the plant enters the vegetative stage. You will see new leaves faster.

  • Watering: increase the volume gradually, always letting it dry out between waterings.
  • Nutrients: if the substrate is poor, introduce a very mild dose of grow fertiliser (¼ of the recommended amount). If your substrate is already enriched, wait a little longer.
  • Transplanting: if it outgrows its pot, this is a good time to move it to a bigger one (photoperiod plants only; see note below).


📋 Reference parameters


  • Temperature: 22-26 °C
  • Humidity: 65-70%
  • Photoperiod: 18 h light / 6 h darkness
  • Watering: little and often at first, letting it dry between waterings


⚠️ Most common mistakes


  • Overwatering: the number one cause of lost seedlings. Waterlogging drowns the root.
  • Too much light or nutrients: "more" is not "better" at this stage.
  • Rough transplanting: damages the young roots.
  • Cold draughts directly on the seedling.


🌓 Autoflowering vs photoperiod


  • Autoflowering: they don't depend on the photoperiod and shouldn't be transplanted. It's best to germinate them directly in their final pot to avoid stressing the root.
  • Photoperiod (feminised and regular): they allow transplanting and, later on, you control flowering by switching to 12/12.


With this care you will reach the end of the third week with a healthy plant ready to grow strong.

Coming from germination? Check our Germination Guide. Specific questions? Write to us by chat.

    • Related Articles

    • Highbreed Seeds Germination Guide

      Highbreed Seeds Germination Guide Germination is the first and one of the most important steps in growing cannabis. Following the process correctly ensures strong, healthy plants from day one. At Highbreed Seeds we want your seeds to get the best ...

    • My seed didn't germinate

      If you have sown a Highbreed Seeds seed and it isn't germinating, don't give up on it just yet. In most cases there is a simple explanation and a solution. This guide helps you work out what happened, what you can still try and, if it really is a ...