Gardening

Yes, and it works great. However, it only has potassium, as well as trace minerals like calcium, magnesium, iron, etc. It's not a general purpose fertilizer though... You need the N and the P in N-P-K too. K (potassium) helps plants grow big roots and fruits. But before the plant can do that you need lots of N (nitrogen) to grow leaves, and some P (phosphorus) to make flowers. I'm generalizing but you get the idea.

So if you're fertilizing potatoes after they've flowered, it's great because it helps the potatoes bulk up. Same with strawberries, fish fertilizer tends to make them grow new leaves, seaweed helps grow big berries.

I typically use fish fertilzer early in the season, then switch to both during flowering, then seaweed only for late season. Apply according to the instructions on the label. They vary in concentration and may include other chemical and/or organic fertilizers to balance the N-P-K.

I personally like using liquid fertilizers. You have to apply more regularly (every 1-2 weeks) but if gives you better control. Using solid organic amendments can be tricky because you typically add them once or twice per season, so you're kind of locked in. Chemical fertilizer works great but is bad for your soil and the environment long term. You can also burn your plants if you're not careful. With organic liquid fertilizer you can support the soil microbiology, quickly correct any nutrient deficiencies, and you won't burn your plants.

All that said, what works best for you is a combination of climate, soil type, pest pressure, crop type, cultivar and a whole lot more. There's no one-size-fits-all when it comes to gardening so you'll just have to experiment and figure it out, which is half the fun. And hopefully the other half of the fun is eating 😋