Among the vast primula tribe, the candelabras (section proliferae) are the easiest to grow, and hence much loved by gardeners who have a bit of damp and not too much heat. They aren’t especially fussy about soil type – some grow on limestone in the wild – and are, in general, usefully perennial and resistant to abuse. Their chief enemies are slugs (which gnaw out the resting buds) and moles, which can leave the tap roots dangling in the air of their tunnels. They really don’t like heat, though, and can be weakened by too much of it, after which they may succumb to all sorts of horrors.
There are many different ways of using these plants, but I use them to form blocks of colour rather than mixing them up. Their colours are intense, and can clash badly with each other if you are not careful. Some gardeners like this effect, but I don’t, so I avoid mixed candelabra seed.
Primula ‘Inverewe’ grows happily with me in soggy yellow clay but many people find it difficult. It’s a hybrid, so has to be propogated by division. The intense orange of a bed in full flower is wonderful, but you do need to be a bit careful where you put it, as it dominates everything around it. I find it almost immune to cold, wet, or disease, and it grows happily with its tap roots down to the (non-stagnant) water table.
Primula puverulenta is equally intense in colour – and needs to be kept well away from ‘Inverewe’. It’s a lot more temperamental – largely because slugs will attack any weakened plant – and a lot less fond of clay. It also picks up a virus which stunts the leaves. I grow mine in deep wet compost, but with the roots kept above the water table. It’s a greedy plant and needs annual top-ups of humous-rich material. Part of the attraction is the meal (farina) which coats the stems in silvery yellow. Most of the prolifera are promiscuous in their habits, so you are better to propogate by division if you want to maintain a particular shade (see splittting candleabra primulas). However, p.pulverulenta sets seed readily, and it germinates equally readily, so you can build up a big collection quite rapidly.
For the orange/yellow shade, I rely on p.bulleyana. This is a really tough primula, which will even survive in turf (wet turf). It’s slower than the others to emerge in Spring, and usually flowers a week or two later – which is annoying. It gets mixed in with p.chungensis, which has flatter-faced flowers and lacks the crimson shade in the young bud, but is otherwise very similar. But the general tendency among the proliferae not to be too fussy about interbreeding means that trying to grow distinct species is usually a fool’s game. p.bulleyana refuses to set seed with me, so I divide it now and again. It forms fewer offshoots than the others, so it takes a little longer to build up a substantial block.
Finally (for the moment) we have p.aurantiaca. The virtue of this plant is in the black/dark red flower stem, which contrasts well with the vivid orange of the flowers. It’s smaller than the others, seems to appreciate rather more shade, and likes the soil a bit dryer (though certainly not dry) It’s slow to make clumps you can divide, and doesn’t set seed with me, so you need to take a little more trouble with it. Along with p.pulverulenta it dislikes having its roots undermined by moles, though slugs seem to leave it alone.
These primulas ought to grow in any garden that is reliably damp and reliably cool for the growing season. Winter (as always with primulas) is the time of most danger, unless you can provide good snow cover from October on. p.pulverulenta is particularly susceptible to rotting in mild rain-sodden winters.