My June Garden: Growing Canna, Pruning Lilac, Fertilizing Trees & Shrubs

Part of the fun of gardening for me is that there are always new things to learn. Recently, I learned something new about fertilizing trees and shrubs, about growing canna outdoors in containers, and about pruning lilacs. Where did I get my information? I asked Ruth Clausen the horticulturist and author, and John Hoyt a local arborist who works in my garden!

Pruning Old-fashioned Lilacs— John Hoyt recommends that pruning be done when it’s a little cooler (early morning or evening) to avoid stressing the shrub– and only after this year’s blooms have faded. Try to avoid pruning when it’s raining or very damp to prevent transmission of disease. Lilacs have a tendency to get leggy so if that has happened to your lilac make your pruning cuts low on the shrub. This will help spur new growth from the bottom and rejuvenate the plant.  You can prune up to 1/4 – 1/3 of your lilac in the spring as needed.  If it has been pruned regularly and is not leggy, then go for aesthetics.  John prunes lilacs to have a light and airy habit, almost rangy. Branching has a cup-like feeling rather than a straight up and down verticality. He’s an artist with the pruning shears in my opinion!

Growing Canna in Containers — I am growing a gorgeous canna outdoors this year for the first time. I asked Ruth Clausen if I can cut back any of the stems to encourage more fullness and more blooms.  She said No, let the buds and flowers grow on their own. If you cut off a stem you will likely cut off a future flower — or inflorescence.  Within each inflorescence are several individual flowers that bloom at different times.  Snap off ones as they fade. When the entire inflorescence fades you should cut off the stem but not the leaves below it.  At the end of the season you can move your plant indoors to a cool, dark place to overwinter.  Temperatures should not go below the mid 40’s.  Keep it a bit moist.

Fertilizing Trees and Shrubs — My first instinct when I see signs of stress in a shrub or young tree is to grab a bag of fertilizer.  John Hoyt says that fertilizing will only cause a spurt of above-ground growth at the expense of healthy root development.  If you really feel your soil is lacking in something the plant needs then take a soil sample and test it to determine whether a fertilizer can help provide what is needed.  Select your fertilizer accordingly.

We’d love to hear what you learned in the garden this week!  Please share in Comments or on Instagram and Facebook.