Calgary Horticultural Society: Lessons learned from a water-restricted summer

Thank goodness for those rainy days at the end of August. With rain barrels filled, limiting water use in September isn’t a terrible situation for gardeners. After all, some years there is frost by Sept. 11. If frost threatens, many gardeners harvest their vegetables and shut down their gardens instead of reaching for protective covers. Cutting back on watering is part of putting the garden to bed for the season.

In the past, we may have reached for the hose to wash soil off our root vegetables before storing them, but it is better to let the soil dry on the crop, and then brush the dry soil off before placing them in storage. While the crop looks cleaner when washed, extra moisture can inhibit the toughening of the skin of root vegetables such as potatoes and carrots and the paper development on onions and garlic; characteristics that improve the storage life of these crops. Extra moisture can result in mould growth and cause rot, shortening their shelf life. Letting the garden bed dry a bit before harvesting starts the curing process for storage.

Putting the garden to bed doesn’t mean we should be putting the hose away. Cool dry conditions in September encourage bud formation on deciduous trees and shrubs. These buds are the growth points for next year. If a tree is ready for winter, you should be able to see a plump bud at the end tip of a branch, even if it still has green leaves. After the tree loses its leaves and just before the ground freezes, it should receive a deep watering to ensure the roots have moisture available to start its growth next spring.

As we get ready for winter reflect on the season. Did you have pests? Many gardeners encountered aphids in their yards; the common green aphid, but also black, red, and woolly. Some aphid infestations on trees caused them to weep enough honey dew (an aphid excretion) to make the area beneath them sticky. While the August rains may have helped wash the aphids off the plants, if you still have some and want to manage them, put on your gardening gloves, and wipe them off with your fingers. After the affected plants drop their leaves, be sure to clean them up. Do not let the fallen leaves provide overwintering shelter for the pests.

Consider which plants were or were not affected by reduced watering. The hardy big-root geraniums (Geranium macrorrhizum) outside my fence never received any supplemental watering and did fine. The tap-rooted Macedonian scabious (Knautia macedonica), the peachleaf bellflowers (Campanula persicifolia), peonies, and roses had a stellar year. The moisture received in May and the cycle of rainfalls set them up for the whole season. However, the hardy kiwi vines (Actinidia arguta) planted last summer became stressed and benefited from extra watering. Hopefully, in a couple more years when they become established, they will be more resilient.

We get our earliest spring colour from spring-blooming bulbs. Did your garden have a nice display of crocus, squill, grape hyacinth, tulips, and daffodils? If not, late September to mid-October is bulb planting time. The bulb is a moisture reserve for the plant, so they are quite drought tolerant. If the soil is not bone dry, it is not necessary to water them in when you plant them. They need moisture to encourage root development, but then they should go dormant until spring. If they stay dry, they will remain dormant until conditions in the spring are right for growth. Without the fall head start, blooms may be delayed.

In reflection, what else did we learn this summer? Water is a precious resource. In the past we may have used it unthinkingly, routinely turning on the tap whenever we wanted some. We have gained an appreciation of how fortunate we are to normally not have to worry about access to clean drinking water.

Water, soil, plants, pests, and planning. There is so much to learn about gardening here. The gardening season is wrapping up, but school is in. Visit the What’s Happening Calendar on calhort.org, the Calgary Horticultural Society’s website, for talks and workshops that may interest you. For a deeper dive into these topics, see the Master Gardener Program. To plan your garden and address watering concerns, look for the four-part Design Your Yard workshop. Be ready to make every drop count next gardening season.