Aquilegia belong to the buttercup family (Ranunculaceae) and are at their best from the end of May into mid/late June. There are approximately 70 species of Aquilegia but the most common in gardens is A. vulgaris which has many different varieties. Other Aquilegia that can be found in gardens include A. canadensis, A. formosa, A. fragrans and A. flabellata to name just a few.
The main problem with these beautiful plants is promiscuity. Taking my own garden as an example, I have never planted any A. vulgaris types at all in the back garden, but they are coming up in all sorts of inappropriate places (through the middle of a clump of Epimedium, shading out a Paeonia cambessedesii as examples. The colour variations are from blue through pink and white plus any combination. These plants are almost certainly from the vulgaris group commonly known as Granny’s Bonnet and include the double Barlow Group as well as a plethora of single short-spurred varieties. In the front garden we have A. fragrans which was grown from seed along with A. canadensis. These were planted on purpose!
As already noted, they are very good doers and will grow in any reasonable garden soil in full sun or dappled shade. To control the spread, I tend to cut off the seed heads before they open. I will allow the odd favoured plant to mature its seed head and as the seed capsule starts to split, cut the head off and tip into a paper bag with a label. Seed can be sown straight away or left till February.
Do not be put off by what I have said about these beautiful plants. Aquilegia are the quintessential cottage garden flower and if you don’t mind them coming up everywhere then let them seed. If you want to exercise some modicum of control, then cut the seed heads off before they mature.