I think Silvia is the one to ask about this. She's an old hand at growing it. I have no luck putting it into the ground. I only grow it in pots, and it gets leggy and ugly quickly. You can cut it back a bit to freshen it up.

Mine is in a pot, I did cut it back, but the leaves are yellowing. Makes me think too much water, but If I let it dry out it seems to wilt. Maybe it's just short lived? The neighbors I got it from, their plants still look lush and happy. Might just be one of those plants I wasn't meant to grow (there have been a few...).

Nasturtiums are the easiest flowers to grow for me, I think the key issues are to plant them at the right time, when it is colder. A few years ago I planted different varieties in a soil that was not amended and they reliable come like a clockwork every season when it starts getting cold, after that they only get water from the sprinkles or rain. I have mostly oranges, yellows, few red, some variegated foliage.

When the heat start to come and they start to decline I pull them out, leave some seeds behind and cover with some hay that is already there.

Try them again in the fall in a place where they come back every year unattended or if in a pot put a lot of seeds like in a hanging basket. Mine are in full sun and so are the displays in containers at Epcot.

Epcot

Silvia

Thanks! I guess it's a winter annual and I shouldn't blame myself that mine is declining now that the weather is warming up.