How do you grow them? What soil conditions are best, and what aspect/location?

 

They are placed into two types, Corms and herbaceous.  

Corms

 cover a very wide over 300 specie and many more hybrids, some of which are difficult for the average gardener to grow, needing special conditions such as alpine houses or frames.  However there are a few spectacular plants that are (bomb proof) in most gardens.  There needs are simple and listed as follows:-

Solida and their hybrids.  A well-drained soil in sun or partial shade.  

There are others that fall into the solida conditions these are Corydalis Decipens, Tauricola, Paschei, Ruksanii, Vittae and Zetterlundii.  But are harder to source.

Cava group.  Peaty soil in dappled shade.  (If buying corms plant on their side so that water doesn’t rot the corm)

Malkensis well-drained soil in sun (bomb proof) beautiful white flowers.

Herbaceous

these are probably the easier plants to grow as long as they are given the correct position.  The majority fall into the woodlander type and require moist well drained soil slightly acid and protected from hot sun.   A mulch of leaf mould and a feed of blood fish and bone once a year will maintain healthy plants they can withstand temperatures down to minus 10 to 15 C but do not like high temperature above 25 degree C.  The key to success is moisture throughout the year.  Many of the Flexuosa and Elata groups go dormant in the summer, but they still require moisture to maintain their rhizomes that are close to the surface.

There are a few others that are fine anywhere in the garden they are listed below, some are annuals or biennials but generally seed around so you will not lose them.  (Some are thugs that you may not want to entertain)

Corydalis Lutea  (thug extraordinaire) Yellow flowers April to October (All seeds are viable)

Corydalis ochroleuca lemon and white flowers as above

Corydalis taliensis pink-purple flowers in spring and off and on to mid-summer

Corydalis cheilanthifolia yellow flowers March – November evergreen

Corydalis ochotensis yellow flowers all summer short lived perennial seeds well*

Corydalis ophiocarpa good foliage wish washy flowers evergreen*

Corydalis noblis yellow flowers in spring brilliant flower*

Corydalis smithiana red – pink flowers spring (A)*

Corydalis linstowiana blue flowers all summer and autumn scented (A)*

Corydalis sempervirens pink and yellow flowers all summer (A)*

Corydalis Curviflora, leucantheon, foetida and buschii.*

* All of which are hard to source.

  What kind of maintenance do they need? 

Generally they are once established fairly maintence free they do not like over crowding an annual feed and mulch and as security take seeds or split the plants.  

 What’s your personal favourite and why? 

I really don’t have a favourite, because they flower at most times of the year different species are in favour at different times.