Keep in mind that you are growing your plants from seed so you'll want to allow enough time for your sprouts to get strong enough before re-potting. The biggest mistake you can make when re-potting is getting over-eager and re-potting your sprouts before they are ready. Disturbing the root system will do more harm than good, so you don't want to take any chances!
If you are growing our bonsai tree seeds, you should have one strong sprout in each pot after completing the thinning process to eliminate any weaker sprouts. These sprouts can continue to grow in their starter pots for up to 1 year before they need to be re-potted. If you have more than one strong sprout per pot, you will need to re-pot earlier so that your sprouts do not overcrowd each other. Don't forget to add more nutrients to the soil as needed to keep your sprouts healthy and thriving. For more tips on re-potting bonsai tree seeds, download our Bonsai eBook here .
If you are growing herb seeds, herbal tea seeds, pepper seeds, cactus seeds, or succulent seeds, you will want to re-pot your sprouts into larger pots once they are strong enough and after thinning any weaker sprouts. You can add more nutrients to the soil after thinning to help your sprouts thrive. When your sprouts are strong enough to re-pot, you should be able to give them a little tug without them coming completely out, but of course, you don't want to go tugging on your sprouts too soon as you'll pull them out of the soil. Once your sprouts are about 4-5" tall they will be getting strong enough for re-potting.
Use a nutrient-rich soil when re-potting your sprouts and keep some of the original soil to help your sprouts adjust to the new soil.
Do not re-pot your sprouts in the sun - the best time is late-afternoon/evening once the sun has started to go down.
Be gentle! Re-potting can be a stressful experience for your sprouts so be careful not to damage the roots or the plant. Gently squeeze the sides of your pot to loosen up the soil so that you can easily remove the sprouts without pulling them.
Once you've re-potted your sprouts, water the soil enough to thoroughly moisten.
The new soil will have nutrients so you do not need to add more nutrients right away when re-potting, but you will need to add more later on down the road. Read the instructions on the packaging for feeding instructions and don't forget to dilute while your sprouts are still small.