August in the garden marks a transitional time in the high desert. While summer is still in full swing, savvy gardeners know it’s time to prepare for cooler days ahead. From planting fall vegetables to managing pond ecosystems and refreshing tired garden beds, there’s no shortage of things to do. Let’s explore August’s Top Ten Gardening Tips with expert-backed insights from Greenhouse Garden Center.

Our Top Ten Gardening Tips for August

1. Refresh Annuals and Perennials
   Mid-summer stress can leave even the hardiest plants looking weary. August is the perfect time to trim back leggy annuals and prune tired perennials to encourage new blooms as we head into fall.
2. Divide Iris and Daylilies
   Dividing these hardy perennials every 3–5 years helps maintain bloom production and prevents overcrowding. Look for clumps with reduced flowering and carefully separate and replant them now for vibrant flowers next season. Bare root iris selections are abundant in early August, so pay us a visit to expand your collection!
3. Plant Cool Season Veggies
   August is ideal for planting fall-harvested crops. Mid August is time to sow seeds of broccoli, kale, Brussels sprouts, cabbage, cauliflower, and collards. These frost-hardy veggies thrive as temperatures cool and often taste sweeter after a light frost. Leafy greens like lettuce, Swiss chard, spinach, and salad greens can be sown now too, especially if shaded by taller crops. Veggie starts could start showing up in the nursery as early as Late August-Early September, should they be available from the growers then.

Pro Tip: According to our Cool Season Veggies Guide, staggered planting every two weeks ensures continuous harvests into late fall. Start now for success.

4. Plant now for fall color
   Plan ahead for fall! A late summer planting of trees, shrubs, perennials, or even annuals can give you a full display of color come fall. Visit with one of our plant experts for advice on which plants will thrive in your garden and give you that fall performance we all desire!

Pro Tip: Check out our Trees & Shrubs for Autumn Color Guide to get started!

5. Harvest Tomatoes, Beans & Squash Often
   Frequent picking encourages more production and keeps plants healthy. Try to harvest daily if possible, especially during peak ripening.
6. Watch for Powdery Mildew
   This fungal issue is common during late summer. Reduce overhead watering, space plants for airflow, and treat early with fungicide if needed.
7. Treat for Grubs
   If you notice dead patches in your lawn or wildlife digging, it could be grubs. August is a good time to apply organic grub control to prevent future damage. Bring in photos of your lawn for a diagnosis if you’re unsure of what is causing your browning.
8. Fertilize Now
   Fertilize your lawn in late August using Sustane All- Natural Fertilizer or Master Nursery Master Green Lawn Food. Your trees, shrubs, and blooming things will appreciate some fertilizer too. Come see us to narrow down which fertilizers will be best suited to your garden! Don’t forget to toss some into your veggie garden too, if you haven’t already.
9. Re-Mulch Beds
   Top off mulch in your garden beds to help regulate soil temperature, retain moisture, and suppress weeds. Be sure not to pile mulch against plant stems.
10. Mid-Summer Pond Care
    Pond maintenance is crucial this time of year. According to our Seasonal Pond Care Guide, summer tasks include thinning and fertilizing aquatic plants, skimming debris, and monitoring water levels. Keep filters clean and remove snail eggs from lily leaves. Watch for fish spawning behavior and keep water at optimal levels to reduce stress during hot spells.

Pro Tip: grab our Pond Plant Handling and Pond Site Selection Guides too!

August may be the last full month of summer, but it’s also the beginning of a new gardening season. Whether you’re sowing cool-season vegetables, refreshing perennials, or managing your pond, now’s the time to plan for fall—and even spring! Visit Greenhouse Garden Center for expert advice, tools, and plants to help your garden thrive year-round.