Peonies stopped growing and froze in time

Question

In March this year, before the lockdown, we purchased 2 peonies in our local garden center in the south east of London which were about the same size: Sarah Bernhardt and Karl Rosenfield. Picture of our peonies is at the bottom of this question. We re-planted both of them in early April to the spot where they are now. After re-planting,

1. Sarah Bernhardt carried on growing and even produced a bud on top. Unfortunately towards the end of April that bud dried out, and the plant stopped growing. All the other new shoots coming from its root were drying out as well.
2. Karl Rosenfield was growing way slower and also stopped.

Both are looking exactly the same for already 2 months, they are neither dying nor growing. We fed them once with slow release multi-purpose granules based feed when we replanted them in early April. We din't plant them deep as it was recommended online in many gardening blogs.

Questions:

1. We read that peonies dislike re-planting, but since Sarah Bernhardt doubled its growth since re-planting, could that be the actual reason?
2. What did we do wrong to cause them to stop their growth?

Answer 1

Paeonies like a sunny position in fertile, free draining soil, so incorporating some composted animal manure or other composted materials prior to planting is helpful, but doesn't sound like something you did.

Despite not liking wet soil in winter, or poorly draining soil, as you planted them in April and the weather then turned very warm and dry for a few weeks, it's possible you did not water them sufficiently well. That would explain the drying bud and dying back leaves on one of the plants. New planting done in spring always needs plenty of water during spring and summer, until the roots have had time to spread out and go down deeper into the soil - the rule with watering is to water quite deeply and less often (say every week, or after 5 days if its really hot and dry), rather than a little water more frequently. They also appear to be planted less than a foot away from the wall behind, which might mean they are suffering from something called 'rain shadow', which means, when it rains, because they are so close to the wall, they do not get sufficient rain to their roots.

If the soil is free draining and seems quite dry about 3 or 4 inches down, water them thoroughly. Check periodically how dry the soil is, and keep up with the watering as necessary. Do not give any more fertilizer this year, wait till next spring now.