Mulching Cool- and Warm-Season Plants

Different plants prefer different growing conditions. In general, cool-season plants like cool and quite moist soil, and warm-season plants like warmer and, often, a little drier soil. Mulch each accordingly, taking into account the soil temperature and soil moisture at each time of the season to create the ideal soil microclimate for each set of plants.

Mulching Cool-Season Plants

Broccoli, cauliflower, and other cabbage family crops (brassicas) like quite moist, cool soil but are often still in the garden when air and soil temperatures have increased beyond their ideal and dry summer weather has become the norm. To keep them happy all season long, you can usually mulch these plants heavily (one-to-three inches) soon after they’re put in the ground.

However, if you’re currently battling slugs or having an especially wet season, wait a bit to apply the same thickness of mulch. Slugs use the thick mulch as a daytime sheltering spot from which to venture out for nighttime feedings on your seedlings. If you have an overabundance of slugs waiting to munch your seedlings, wait until you get their population under control or until the seedlings are so big that a little munching won’t faze them. Just get the mulch on before the weather turns too warm or too dry and your brassicas will be mostly happy until harvest (They’ll still be stressed by their leaves being in the heat, but that can be helped by using the correct row covering, discussed in another section.).

Many cool-season crops (e.g. peas, lettuce, spinach, and carrots), don’t typically need much mulch. They either provide enough mulch for themselves from their foliage (e.g. carrots, spinach, and lettuce) or are done when the hot weather hits whether they’re mulched or not (e.g. spinach, lettuce, and snap peas). Other than possibly a very light sprinkling of broken-up straw to keep the soil moist and protected from compaction and erosion just after planting while the seeds are germinating and emerging seedlings are little, leave them un-mulched.

Mulching Warm-Season Plants

Most warm-season plants (e.g. tomatoes, peppers, eggplant, corn, beans, melons, and squash) need the soil to heat up a bit to germinate and grow well. Some (e.g. peppers) even seem to prefer a little drier soil or at least tolerate it well. Typically, wait to mulch peppers and tomatoes, if at all, until they are really growing strongly and rain starts to be less frequent. Also, usually mulch them fairly lightly—from a thin sprinkling that covers probably only about ⅓ to ½ of the soil’s surface area to around an inch thick, depending on the weather that year.

Other warm-season plants need no mulch at all. Some are fine without it (e.g. corn) but don’t mind it. Others, quickly make their own “mulch” with their robust foliage (e.g. squash, sweet potatoes, and bush beans), making it mostly superfluous. You don’t have to mulch these at all unless it’s an especially dry year. However, mulch also helps grow the organic matter in the soil, so adding some is still often a good idea.

Beyond these basics, gardeners can also adjust the timing and thickness of their mulch to create “perfect” microclimates for their seedlings, making up for the vagaries of weather in just about any year.