Written by: Jan Dash Colorado Master Gardener 2024 

Summer gardening is a whirl of activity. The flowers need planting before it’s too hot for them to thrive. The mulch needs refreshing to stop the weeds from taking over. And after the first bloom, flowers need to be deadheaded to keep the color coming. It can feel overwhelming to keep up with, but a summer garden checklist can help you focus your efforts where it matters most. As you cross off each task, you’ll be maximizing the beauty of your garden and supporting the health of your plants. 

A list of garden tasks by month can be found on the Pueblo SHED (Supporters of Horticultural Education) website <https://puebloshed.org/gardening-calendar/>. A simple internet search will also provide endless lists of monthly gardening tasks. Just be sure to check which growing zone they are referring to and select sites with .edu endings in their address. If you forgot which zone you’re in, the USDA plant hardiness zones can be found here: https://planthardinessarssda.gov. For in-depth discussions about any of the following checklist items be sure to visit the CSU Extension website at https://extension.colostate.edu/topic-areas/yard-garden and select the desired publication. For example, the Gardening Basics section includes publications about drip irrigation for home gardens, home sprinkler systems, and mulches for home grounds, to name a few. 

You can do as many of the tasks as you like or have time for, but controlling weeds and pesky insects, maintaining a healthy height for your lawn, and providing sufficient water are musts. 

The following is a compilation of tasks from various checklists. 

Ongoing – May through September 

• Control weeds in flower and vegetable beds and lawns. 
• Pluck out weeds when you see them. 
• Add several inches of organic mulch to the beds. 
• Look for an organic weed control method to eliminate difficult weeds. Start your search with the CSU extension website. 
• Mow lawns to a height of about 3 inches; mulch clippings and leave on the lawn.  
• Water lawns as needed; lawns may need 2.5 inches of water or more per week.  
• Overseed lawn bare spots throughout the summer. 
• Water container plants daily or as needed.  
• Water plants in beds at ground level as needed based on your area.  
• Water vegetables and herbs as needed and try to do this in the morning. 
• Hand-pick and/or spray insects when you see them to reduce damage.  
• Harvest and preserve vegetables, fruits and herbs.   
• Dead head flowering plants, both annuals and perennials to promote re-flowering. 
• Save seeds from the best performing plants for planting next year. 
• Remove dead wood from trees as it becomes apparent with leaf-out. 

June 

• Fertilize seedlings as needed.   
• Mulch beds, gardens and trees. 
• Finish pruning your spring-flowering shrubs this month before they start to set buds for next season. 
• Examine your fruit tree branches and consider thinning some of the fruits. Some fruit is shed naturally but you may want to help the process. 
• Start your regular lawn and garden irrigation. Monitor soil conditions and increase settings as needed. 
• Replant warm season seeds that did not germinate. 
• Be on the lookout for pests such as grasshoppers. Catch and kill the young nymphs before they can mature. Refer to CSU Extension fact sheet 5.536 for some suggestions on grasshopper control. 
• If you don’t already have one, and if it is allowed in your area, set up a rain barrel for supplemental water for your gardens (see CSU Extension fact sheet 6.707).  
• Consider adding a compost bin to a corner of your garden. See CSU Extension fact sheet Number 7.212 for composting yard waste. 

July 

• Plan on cool season vegetables for late fall harvest.  
• Start seeds indoors late in July so the plants are ready later. 
• Remember to plan on fall flowering plants such as sunflowers, marigolds, alyssum, nasturtium and cosmos to encourage pollinators to stick around. 
• Prune and shape non-spring flowering shrubs and hedges. 
• Cut back non-fruiting blackberry and raspberry canes. 
• Remove tomato suckers and prune plants to select the best fruiting branches. 
• Cut back the top inch or two of new growth on fall perennials early in July to promote a bushy habit and abundant blooms 
• Replenish mulch where needed. 
• Inspect your lawn for dry and/or stressed areas and adjust, repair or replace sprinkler heads. 
• Apply an organic fertilizer to your lawn to replenish nutrients. Hanging baskets and containers could also use a boost of nutrients. 
• Divide daylilies and irises. 
• Monitor for pests that like the heat, spider mites and Japanese beetles are a couple of common ones.  

August 

• Plant cool season vegetables.  
• Remove seed heads from plants you don’t want to self-seed. 
• Buy perennials on sale to fill in or expand planting beds.  
• Continue to harvest vegetables. Remove spent plants and dropped fruits to the compost bin to discourage pests and disease.  

 As temperatures start to dip and your plants begin slowing down, it’s time to observe and take note of what you’ve learned this year and consider what changes you might want to make next year. What varieties did well, and which ones didn’t? What would you like to add to next year’s garden? What worked or did not work with your layout, watering, and mulch. Make notes in your garden journal and put it in a place you’ll reference on that cold winter day when you start dreaming about next year’s garden.