GS Plant Foods All Purpose Water Soluble 20-20-20 Fertilizer Balanced NPK Plant Food with Micronutrients, Contains Kelp (Ascophyllum nodosum) for Indoor & Outdoor Plants, Gardens & Turf (3 lbs)

This one! Might seem pricey but the bag will last a really long time since you only use a couple teaspoons per gallon. I love it because it also contains sea kelp which helps stimulate root health and more growth, and it has lots of micronutrients on top of the main three so I know I won’t run into low iron, etc. Mixes really easily with water. I’ve only used it once on my roses so far, but my plants are thriving. In the days after feeding them, my St. Tropez, which has been by far my most stagnant with some pretty stubborn black spot, started pushing out tons of really healthy looking new leaves and I bet I’ll get buds soon. I also fed my tomatoes with it and they seem to love it! It’s not organic though if that matters to you.