I water the plants once a day and spray the leaves with room-temperature water twice a day.

Sounds to me like you're drowning your plants. You should only need to water once a week by bringing the entire pot to the sink and watering thoroughly with the spray nozzle.

Overwatering is the number one reason why indoor plants die. Just because it appears dry on top doesn't mean it isn't very moist a couple of inches down. Stick your finger in as far down as you can reach to check moisture. So long as it feels slightly damp, you don't need to water.

Roots require oxygen equally as much as they require nutrients and water. Let them breathe. Watering too frequently and too heavily is harder on plants than too little water. They can recover from dehydration but not from suffocation.

Don't water for a week and report back.

Hi Timoka,

If you go to this website www.lycheesonline.com
there is a wealth of information on lychee trees, but it is mostly on air layered trees, not seedlings. It does say they are very susceptible to fertilizer burn, they recommend on using organic fertilizer which you are using (seaweed), because they are very prone to leaf tip burning.Also too much salt also causes this. Maybe cut the strenght of your seaweed by half. Lychees do require a lot of water, I'm just not sure if this applies to newly sprouted seedlings. Although I would guess that it does.

I have two air layered trees that I just planted and some of the leaves have the tips burning and I use fish and seaweed, so I know that this is common. The nursery told me to water them at least once a day for 3 to 4 weeks then every other day for at least another month or two till they get established.

Good Luck!

Thank you for the advice. I watered the plants yesterday, and although it's kinda hard to say, I think the leaves haven't gotten very much new brown. Hopefully the plants will do better from now on.

Good to hear the feedback. Does this mean you gave your roots a chance to breathe some oxygen by not watering for a while?

Yes, I didn't water them for a week. Also, I thought that they breathe carbon dioxide, was I wrong?

Carbon dioxide is produced in the soil by microbial and root respiration with the uptake of carbon and oxygen to produce carbon dioxide.

The roots take in oxygen, and need oxygen to live on.

Here is a link that might be useful: Gas Exchange in Plants

Those are very common syptoms of growing lychees. The tree is very sensitive to the chemicals in the tap water. If possible water with distilled or rain water. I also recommend a potting mixed that is more on the acidic side. Mix with lots of pete moss to obtain this. Unless your temps are very cold, it shouldn't have too much problem with over watering as the plant is a heavy water feeder.