Most gardeners routinely add compost to flower borders and vegetable gardens in spring and fall. But don’t overlook August. It is an opportune time to add compost to your beds and borders, and your fall garden will benefit from the additional nutrients.
If you put down compost in August, your garden thrives in several ways. Compost helps the soil retain water during the heat of late summer, protects the soil and plant roots from baking temperatures, and replenishes nutrients that heavy feeders have used up before this point of the season.
You can use homemade compost or purchase bags, such as this organic compost from The Home Depot, to add as a top-dressing layer around plants in flower beds, vegetable gardens, raised beds, or containers. Trust me, your plants will thank you if you add this to your late summer gardening checklist.
Why You Should Put Down Compost in August
If you put down compost in August, it helps your garden recover from the rigors of summer and puts it in better shape for fall.
For gardeners planning to add new plants to their flower beds or borders in early fall, compost boosts nutrients and improves overall soil health by increasing the activity of beneficial microorganisms.
While lots of gardeners don’t put down compost in August, they are missing out on the fact that organic matter breaks down quicker in the hot summer temperatures than when added to the soil in spring or fall.
‘You get to see the benefits compost offers a little quicker than if you apply it when the weather’s cooler,’ claims Justin Hancock, horticulturist at Costa Farms.
The experienced gardener hails compost as ‘as close to a miracle cure for your soil as you can get’ for its ability to boost various soil types if you put it down in summer.
‘It helps sandy soils to hold moisture and nutrients better, helps clay soils drain better, and increases microorganism activity in the soil – allowing beneficial fungi, worms, etc. to thrive and enrich your soil,’ he explains.
Putting down compost in August helps reinvigorate tired soil and replenish lost nutrients. If you have grown hungry crops like tomatoes, peppers, squash, or potatoes, compost can put valuable nutrients back into your soil in preparation for fall crops.
It is not just a quick fix, though you do get immediate results, as the benefits of putting down compost in August can be felt for many months to come.
‘August is the perfect time to add a fresh layer of nutrients for the fall garden,’ says Nikki Bruner from My Perfect Plants. ‘Not only does it add new nutrients, but it can help contain weed growth, retain moisture, and help boost the soil for next spring too.’
The Best Way to Put Down Compost in August
When you put down compost in August, the best approach is to add it as a mulching layer on the soil surface. Add a 1-2 inch layer of compost around the base of existing plants, spreading it thinly over the surface with a sturdy garden rake (available at Walmart), or 2-3 inches deep over recently cleared areas of the yard.
It is important to avoid disturbing plants already in your beds or borders in late summer – that is why it is better to top dress with compost rather than dig it into the soil.
‘Try not to dig around or disturb roots when there are still hot days on the horizon,’ warns Marian Keith, horticulturist at Newfields. ‘If you're adding compost to established garden areas, top dress with about an inch and don't be tempted to get too heavy-handed.
‘Keep your coverage from piling up at the base of plant stems and avoid the temptation to stir up or otherwise disturb the soil.’
It is a mulching mistake to pile the soil against stems or over the plant crown. Always leave a gap of an inch or two around the plants to eliminate any risk of rotting. It is recommended to water the compost after applying it to the soil.
Siobhan Shaw, co-founder of Growing to Give, warns about using unfinished or hot compost for the task. ‘Finished compost is excellent to apply in August as a top dressing,’ she says. ‘Hot compost can damage plants, tie up nitrogen, burn roots, introduce weeds, and attract pests. I would not put this around actively growing plants’.
A good test for whether homemade compost is ready is that it smells earthy and neutral, is fully decomposed with no recognizable signs of plant material, and is at an ambient temperature rather than warm. As temperature is a good indicator, a compost thermometer (from Amazon) can be a welcome investment.
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August can offer an opportune time to give many plants a late-summer boost so they can flower and fruit strongly into fall.
Anything still blooming or producing fruits, such as roses, dahlias, or tomatoes, is among the most important plants to fertilize in August. As are plants growing in containers that need regular nutrient top-ups to keep performing at their best.
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