How can I raise the humidity in my growtent withou...

Put water in the room, If you can use distilled water. But yes just keep adding till your at the right humidity. Use pales, cups whatever is best for your space ECT. once right just add water as needed.

Try hanging out wet towels, if possible in direct sight to fan air flow, you need lots of evaporation, and keep your grow room very closed. Keep on the great care! Happy smokes!

Use a makeshift humidity dome for the first couple of weeks. I place the seedlibgs in party cups inside a small transparente Rubbermaid with another on top acting as a humidity dome