Although marigolds can be grown in stacked pots in a vertical garden, a better place for them is at the bottom pot which collects leftover water and plant food. In this location, they will thrive and can grow over 2 feet long.
When marigolds are positioned in a bottom pot, they will attract bees like Bumblebees(personal favorite) and beautify a veggie garden with multiple yellow, red and orange coloring.
Marigolds can be purchased quite cheap at various retailers. In addition, they are very simple to grow from seed. They can be propagated under led lights with a heat pad to provide stimulating warmth to the root zone.
They fit a 72-cell almost perfectly before they can be transplanted into their final location. Thus, timing their start date around 4 weeks before last frost makes it easy to start and transplant directly from the reusable nursery flat.
Marigold seeds are somewhere between 1/4-inch and 1/2-inch long and can easily be sprinkled into flats by hand. In fact, asides from a vacuum seeder, hand sowing is actually easier and faster than a manual seed sower.
If we add an extra one or so in each cell, we do not need to worry. We can transplant germinated seedlings afterwards with a mini spoon, if we have more than one in each cell.
Around the 4 week mark, marigold seedlings will start to produce their first flower buds. Often, we will transplant them at 4-5 inches high with bud(s).
Marigolds will dry up and die as the season progresses. For the seed enthusiast, the dried seeds can be collected and stored in a cool, dry place for years to come.
Although marigolds can grow best with lots of water and nutrients, spare plants make a nice addition to most soil types, except real dry soil that does not get watered enough.
More seed information can be found at the following links.