Do I Have to Reapply Mulch in Midsummer? How to Know When It's Time to Top Up Your Beds
Mulch rarely lasts all season. By July, it has often thinned out, leaving beds exposed as heat peaks. Here's how to tell if you need to reapply more mulch now.
Mulch put down in spring feels like a one-and-done job, and for plenty of gardeners it is – right up until midsummer, when the beds start looking thin and the ground dries out faster than it used to. That layer that was 2 to 3 inches (5-8 cm) deep back in April has a way of settling and quietly vanishing by July. Whether it calls for another bag or two really depends on what's left on the ground.
Any solid guide to mulching will stress that organic mulches are meant to break down over time – that's the point. They not only hold in moisture and cool the soil, but they also add organic matter into the soil as they break down. The catch is, though, is that they don't last forever. So a midsummer mulch refresh is often the price of that slow-release payoff.
Not every landscape needs another layer of mulch in the middle of summer, though, and heaping more where there's already plenty brings its own set of headaches. I'll help you know if your garden needs another layer of mulch, how much to add, and the best type to refresh gardens in midsummer.
Why Does Mulch Disappear?
A few different elements eat away at mulch over the course of the summer season. Living organisms in the soil break down the lower layers of mulch over time, which is actually a good thing. The mulch turns into exactly what your plants want and need to thrive.
But the surface layer of your mulch is another matter. Sun bleaches and dries it out, and hard rain packs it down flat. Week by week, a fair amount of mulch gets kicked around by normal tending and foot traffic or blown clear of the bed by the wind, too.
How fast this occurs comes down to the cause and the type of mulch you used. Shredded bark and wood chips hold up for a good while, often a full season or longer. Lighter materials – think straw or grass clippings – break down quicker and sometimes they're almost gone by high summer. Stone and gravel mulches don't break down at all, though they don't feed the soil either, which is why most flower and vegetable beds benefit from an organic mulch.
Do You Need to Reapply Mulch?
A simple test to check if you need more mulch and when to mulch in summer only takes a few seconds. Just push a ruler down through the remaining mulch until it hits soil and see how deep the layer actually is. Anything under an inch (2.5 cm) or so isn't pulling its weight anymore. It won't hold in much moisture or do much to smother weeds. Bare patches where the dirt shows through are the other easy giveaway, since that's where water evaporates fastest and weeds find their opening.
Weeds tend to reveal on a thin layer of mulch, too. A bed that was clean in spring suddenly throwing up seedlings usually means the mulch has worn past the point of blocking them.
Moisture is the other tell. If the ground under the mulch dries within a day of a good watering, the cover is too skimpy to hold much moisture. A basic soil moisture meter from Amazon takes the guesswork out of this, though honestly a finger pushed a couple inches (5 cm) into the dirt works nearly as well.
How Much Mulch to Add
The goal is a finished depth of 2 to 3 inches (5-8 cm), not two to three inches of fresh mulch piled on whatever's already sitting there. Topping up means adding the difference and nothing more.
If an inch (2.5 cm) of mulch is still holding, another inch or so brings it back where it should be. Too much mulch, anything deeper than 3 inches (8 cm), and it starts working against you by holding too much water against plant roots and preventing the soil from breathing.
Keep the fresh mulch layer pulled back a couple inches (5 cm) from plant stems and the base of shrubs or trees. Mulch heaped straight against bark traps moisture where it isn't wanted and invites rot. Those mulch volcanoes you see around trees are a common mulching mistake and are actually really bad for trees.
Spread and level out mulch with a rake. A sturdy landscape rake from Amazon spreads a bag evenly in a fraction of the time of doing it by hand and keeps the depth consistent across the whole bed.
Best Mulch for a Midsummer Refresh
For a summer top-up, you want a mulch that holds moisture well and stays put through thunderstorms. Shredded bark and wood chips are hard to beat for use around shrubs and perennials. They knit together and resist blowing away, and their slow breakdown process helps them last right into fall.
Vegetable beds do better with an eco-friendly mulch like straw or shredded leaves, which stay light and work into the soil easily once the season winds down. But matching the new mulch to whatever's already there keeps your landscape looking cohesive.
One task worth doing regardless of the type of mulch you use: soak your garden beds first. Laying mulch over dry ground just locks in that dryness, which defeats the whole purpose. A bag or two of organic shredded bark mulch from Amazon covers most average-sized beds and a good watering beforehand means the fresh layer of mulch seals in moisture.
