Quote:
Originally Posted by Luizacft
Hi, all! Thank you for responding.
1 - I actually live in the south of Brazil - it has cooler temperatures than in other states.
2 - Those pots have holes only in the bottom.
3 - They are in a part of my balcony which they receive no direct sun.
4 - I think I'll use a 1/4 strength foliar fertilizer every week. What do you think of this regime of fertilization for seedlings? Is it too much?
New question: The seedlings are planted in tiny rocks. Would you change the pot mix to bark+sphagnum at this point? Spring will start soon in Brazil and winter is already gone at this point of the year.
I'm really new to this seedling care. Sorry for too many questions. :-)
Thanks in advance!
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They like day to night temperature variations like you get. That is good. Very bright indirect light is good. As they get bigger they can take more light. You don't mention your relative humidity but the higher the better for seedlings.
Don't repot them until they start making new roots and growths. Be careful to pay attention to this. Cattleyas, especially bifoliate ones and seedlings, can be set back badly by repotting when they are not in active growth and making new roots. Before I learned this I repotted some seedlings not in active growth. They sat without growing for almost a year and then died. When I repot seedlings in active growth they continue growing as though nothing happened.
You never want seedlings to dry out completely until they are nearly blooming size. They should be nearly dry when you water again. Pot/medium/hole combination should be selected that fits into your schedule (for example, so you don't have to water three times a day just to keep them alive.) Bigger pots relative to the size of the plant dry more slowly. Smaller medium dries more slowly. Pots with fewer holes dry more slowly.
I can't tell how large your pots and plants actually are, but I would guess the pots are empty food containers. I also use empty food containers for many plants. Your pots look to me somewhat large for your plants unless you use a large medium that dries fast. But, you say they are in tiny rocks. I suspect this dries out very slowly, and I would not use a combination of tiny rocks and a large pot for any epiphyte. I would worry it stays wet too long. If Cattleya roots don't get nearly dry between waterings they are prone to rot. However, don't repot until they are in active growth.
You can use a small thin piece of wood to determine how wet is the inside of the pot. Go to the beginner forum and look for "skewer."
Rain water or very pure water is much better for seedlings unless your tap or well water has very low amounts of total dissolved solids (abbreviated TDS.) You can probably find this information on the Web site of your municipal water source.
I would change my pots or my medium or both, once the plants start growing. I would use smaller pots, diameter no more than 3-4cm wider than the current length of the plant. 1-2cm wider would be good too.
Empty food containers often are deeper proportional to the width than I would like. You don't have to fill the container to the top with potting medium. For your containers I would fill only 1/2 to 3/4 with medium for Cattleya seedlings.
Or, you could put a lot of holes in the sides of your current containers. This would make them dry out faster. Don't do this with the plant in the pot. Some people use an electric soldering iron. Others use a drill with a small carborundum bit intended for grinding wood. In either event don't breathe the smoke and wear eye protection.
I would use a medium with larger chunks, from 1/2 to 1cm in diameter. If your area normally has higher relative humidity, I would not use the moss. If your seedlings are really tiny and the containers very small, I would use smaller diameter medium.
You don't need to fertilizer them much during the winter. When they start growing you can fertilize more. Let them tell you. They need regular fertilizer when they are making and maturing new growths. Opinions vary as to what is a good amount of nitrogen for seedlings and how much to fertilize during both the growing season and the winter. Your main concern should be not harming them with too much fertilizer.
During the winter many people fertilizer only once in 3-6 weeks. Some give no winter fertilizer.
Fertilizers have varying amounts of dry chemicals. You need to take into consideration the numbers on the label and not think in fractions of strength. I would suggest you read about fertilizer
here.
Note there is a calculator on that site to calculate dilutions.
If you use 50-75PPM nitrogen for seedlings you will likely not hurt them. If you use nitrogen in very low PPM you can use that at almost every watering, changing to pure water every 4th to 8th watering, to flush accumulated salts out of the medium. Almost all plants do better with constant small amounts of nitrogen rather than periodic large amounts.
Seedling care tips
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