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Get the Best of the Blues: Part 1: Annuals

© Susan Ward

While there are many plants nursery people and horticultural experts describe as blue, many of these don't have the true blue shade that blue-loving gardeners like me want in their beds. For instance, the Cranesbill Geranium "Johnston's Blue" is obviously described as having blue flowers, but while I agree that this is a great perennial addition to any garden, it always looks purple rather than blue to me.

What to do? Buy your plants in flower, so you can see how truly blue their flowers are. Or, take my word for it. What follows is a list of annual plants that really do have those true blue flowers you've been looking for to add a cooling splash of blue to your beds and borders.

Forget-me-not (Myosotis). Technically a hardy biennial, this will behave the same way as a perennial in your garden; it's a wonderful spreader. Available in a host of varieties ranging from 6 inches through one and a half feet tall, all forget-me-nots have dense clusters of flowers in spring (blooming from late March through May here). Forget-me-nots are very easy to grow; all they need is well-drained soil and occasional watering. They prefer shade, but will grow in sunny sites, too. I recommend "Ultramarine", which is a rich blue.

Floss Flower (Ageratum). I bed some of these every year, because I love the neatness of their shape as well as their colour. This compact annual with hairy leaves and powder-puff flowers forms neat mounds about 6 to 10 inches tall. Grow it in sun or light shade and feed occasionally for best results. Ageratum also needs to be deadheaded frequently and watered well in dry weather. There are many hybrids with shades of blue and mauve. My favourite is "Hawaii Blue", but I have friends who swear by "Blue Mink" as well.

Lobelia. This old favourite became a favourite because of its reliability; in the right conditions, it can be depended on to produce masses of small blue, purple, white, or pink flowers which look great cascading from baskets or tubs or trailing over the edges of raised beds. An annual which grows about 4 to 6 inches tall, Lobelia thrives in sun or light shade, but needs regular feeding, and prefers moist soil. Lobelia "Sapphire Blue" has a deep, vivid colour that I love. You might also want to try "Mrs Cilbran Improved" if you can find it.