As summer begins to wind down, August is a crucial month for gardeners in Southern Ontario. While the days are still warm and the garden is in full bloom, there are several important tasks to ensure your garden remains healthy and vibrant as we transition into fall. Tanya Olsen, third-generation owner of Royal City Nursery and a Professor in the Horticulture Apprenticeship program at Humber College shares with you her top tips & what you should be doing in your garden this August.
August is not the ideal time to divide or transplant perennials due to the stress of the heat, but it’s perfect for giving them some TLC. Keep an eye out for dead or damaged foliage and trim it back to encourage fresh growth. If you’ve noticed any pests or diseases, such as powdery mildew or rust, take action now by removing affected parts and applying appropriate treatments.
It’s not too late to enjoy a second harvest! August is the perfect time to plant cool-season crops that will thrive in the cooler temperatures of fall. Consider planting:
Ensure your soil is well-prepared with compost and mulch to retain moisture and provide nutrients to these late-season crops.
Pest pressure can be high in August, with everything from aphids to slugs making appearances. Integrated Pest Management (IPM) is key—monitor your plants regularly, and if you notice damage, identify the culprit before taking action. Use organic or targeted pest control methods where possible to avoid harming beneficial insects. Learn more in our blog ‘Pests to Avoid’.
To keep your garden looking its best and encourage continued blooming, deadhead spent flowers regularly. For plants that have finished blooming for the season, such as daylilies or irises, you can cut back the foliage as it starts to yellow. Pruning summer-flowering shrubs like hydrangeas and roses not only tidies them up and helps shape them for next year’s growth but also prevents further damage from the weather.
Although it’s too early to plant fall bulbs, August is the perfect time to plan and prepare. Pre-order your bulbs online now—like daffodils, tulips, and garlic—so you’re set to plant them in September and October. Don’t forget to plan for fall blooms with bulbs such as Fall Flowering Crocus (Saffron, Zonatus, and Cartwrightianus) and Colchicum (Waterlily and The Giant).
Start enriching your soil now by adding compost or well-rotted manure to ensure it’s nutrient-rich and ready for planting. Be sure to stock up on Hen Manure to help protect your bulbs from pesky squirrels when planting time arrives.
August can bring hot, dry & humid conditions, so watering your garden effectively is crucial. Water deeply, at the base of the plant (to avoid damaging leaves) and less frequently to encourage deep root growth, which will help your plants withstand dry periods. Early morning is the best time to water to reduce evaporation and ensure plants have moisture throughout the day.
August is a peak harvest month for many fruits and vegetables. Tomatoes, peppers, cucumbers, and zucchini should be picked regularly to encourage continued production. Consider preserving your harvest by canning, freezing, or drying so you can enjoy the flavours of summer well into the fall and winter months.
While you’re enjoying the abundance of August, it’s also a good time to start thinking ahead to fall. Consider what plants you’d like to add to your gardens and yards this fall so they’re ready to bloom come springtime. Whether it’s adding new perennials, creating a vegetable bed, or planting bulbs for spring, now is the time to plan and make notes so you’re prepared when the cooler weather arrives.
August is a good time to do a general garden tidy-up. Remove any weeds that may have sprung up, and clear away debris to keep pests and diseases at bay. Cutting back overgrown plants and tidying garden edges can help maintain a neat and healthy garden space.
With the August heat, your pond may experience increased algae growth. To keep it healthy, regularly monitor and manage algae by introducing beneficial bacteria to balance the ecosystem. Ensure your pond’s water circulation and filtration are working well, as proper water movement helps prevent algae overgrowth. As nights cool down, algae growth will naturally decrease, but consistent care now will keep your pond clear and vibrant into fall.
For tender perennials or tropical plants you intend to overwinter indoors, start planning their transition now. If they’re in containers, consider where they’ll go once the weather cools down, and check them for pests before bringing them inside.
When it comes to houseplants, there’s still about a month before they need to come indoors for the winter. Now’s the perfect time to start planning where they’ll go once inside. If you’re a student or teacher, this is also a great opportunity to think about how you’ll decorate your dorm room or classroom for the upcoming school year. Keep an eye out for our ‘Back to School’ tropicals arriving middle to end of August—we’ll have a fantastic selection of 4” and 6” plants ready just in time for the new semester..
Finally, take time to enjoy your garden in full bloom. August evenings are perfect for spending time outdoors, admiring the results of your hard work, and gathering inspiration for the next gardening season.
By following these straightforward yet essential tips, you can keep your garden beautiful and productive as summer transitions into fall. If you have any questions or need further advice, our team of experts are here to help at the garden centre. Happy gardening!
About Tanya Olsen:
Tanya is a third-generation garden centre owner and landscape designer.
Teaches Horticulture Apprenticeship at Humber College in Ontario, Canada.
Has a weekly segment on CTV news.
Has a Bachelor of Landscape Architecture.
YWCA Woman of Distinction.
About Royal City Nursery:
Guelph, Ontario’s only third-generation, full-service garden centre! We specialize in creating custom outdoor living spaces and unique solutions for all your garden, landscape, and seasonal decorating needs! At our new greenhouse, located between Guelph and Cambridge, we are the garden centre of choice for discerning homeowners, landscapers, and designers.
