I am starting geraniums from seed. The seedlings are currently in a seed tray. Do I transplant them only once? Or do they need transplanted when they have two-three leaves and then again later to a 4” pot? They currently have 3 leaves.
Very small plants are less likely to live outside than those that have reached 4 inches or so. Leaving them in the germination tray will allow the roots to become hopelessly tangled. Most people use 4-6 inch pots to save space under grow lights in this interim stage. Geranium is a confusing term. To many it refers to the annual zonal geranium, Pelargonium. There are several perennial geraniums, an entirely different type of plant. https://www.gardeningknowhow.com/ornamental/flowers/geranium/geranium-care.htm