By Larry Hodgson
Micro-clover—an extra-dwarf variety of white clover (Trifolium repens) with smaller leaves and a lower height—has been gaining ground as a lawn ingredient for the last few years. You can now readily find micro-clover seed pretty much everywhere, both online and in-store. It still remains in short supply, though, and is therefore a bit expensive, but its advantages might still make it worthwhile.
What is Micro-clover?
Micro-clover is a natural variant of white clover originally found in Europe in sheep pastures. After generations of being “mowed short” by sheep on a regular basis, some plants adapted by starting to produce, in response to an initial shearing, lower-growing foliage, therefore less exposed to the sheep’s teeth. Dutch and Danish researchers noticed this phenomenon and were successful in isolating a strain of micro-clover, ‘Pipolina’ (the name means ‘pirouette’), which is naturally low-growing with small leaves. And easily reproducible by seed.
‘Pipolina’ produces trifoliate leaves and white flowers like the dwarf white clover usually used in lawns, but never reaches more than 6 in (15 cm) in height, even if you never mow it. (Unmowed, dwarf white clover grows to 8 in [20 cm] and more.) If you mow ‘Pipolina’ occasionally (and it can be mowed short, as low as 2 inches/5 cm), that stimulates denser, shorter growth that won’t grow taller than 4 inches (10 cm).
Its leaves are naturally about half the size of dwarf white clover leaves, even 1/3 the size when it regrows after mowing. The small leaves of the micro-clover blend better with the grasses of the lawn to help to create a beautiful green carpet.
Also, rather than forming dense patches of green here and there in the lawn as dwarf white clover tends to do, ‘Pipolina’ has, once again after an initial mowing, a more spreading habit, more readily forming a carpet for a more even effect.
However, micro-clover produces fewer flowers than a normal dwarf white clover plant, especially if it is mowed regularly. Even so, the flowers that are produced do provide food for bees and other pollinators.
The Benefits of Micro-Clover
- Micro-clover is a legume and therefore lives in symbiosis with bacteria that fix atmospheric nitrogen, making it available for its own growth and also to neighboring plants. That’s why even turf grasses grow better when there is micro-clover in the lawn.
- A lawn containing micro-clover needs much less fertilizer than a lawn composed only of grasses. Moreover, fertilizers rich in nitrogen are actually not even recommended for lawns where you want to see this clover settle in.
- Micro-clover tolerates compacted soils better than grasses and even tends to lighten very dense soils, reducing the need for aeration.
- Thanks to its deep roots, micro-clover is significantly more drought tolerant than most grasses and will stay green even in times of drought.
- Micro-clover grows very well in sun and partial shade. It is not a good choice for shade (nor are turf grasses, for that matter).
- Micro-clover resists weeds better than grasses and even tends to outcompete them.
- Unlike grass turf, micro-clover is highly resistant to dog urine and de-icing salts.
- A lawn rich in micro-clover discourages lawn-damaging insects, especially white grubs, for whom clover is simply not a preferred food source. In fact, the beetles that produce white grubs tend to avoid laying their eggs in lawns dominated by clover, as they don’t offer their young much to eat.
- Micro-clover is very cold hardy (USDA hardiness zone 3, even 2; AgCan zone 4 or even 3), especially where there is some snow cover during the winter.
There are also some disadvantages to micro-clover, though.
For example, micro-clover seeds germinate a little slower than grass seeds and also tend to germinate less equally. It may therefore be necessary re-sow certain spots that didn’t give good results the first time.
It’s better to use pelleted seeds, which ensure better seed distribution and better germination. In fact, many suppliers, like Gloco in Canada, sell only pelleted seeds.
Micro-clover Lawn or Mixed Lawn?
Yes, you can sow a lawn composed only of micro-clover. That way a single annual mowing will be enough to maintain a lawn that may be a little uneven, but still attractive. If you mow 3 or 4 times per season, much less than for a turf lawn, you can have a micro-clover lawn that’s perfectly flat!
However, as with any plant, a monoculture of just one species is not the ideal situation. It leaves the lawn prone to diverse problems (insects, diseases, etc.) that come to fore when one single species is used. In a mixed lawn, on the other hand, if one plant has a down time, the others compensate and any irregularity won’t show.
Micro-clover, in fact, actually seems to do best when it shares its space with grasses and other plants. And that shouldn’t be surprising, since, in the wild, white clover always grows in mixed company, normally as part of a meadow.
Another advantage of growing a mixed lawn of grasses and micro-clover: clover doesn’t produce thatch, that accumulation of dead grass roots and leaves that forms a thin protective layer on top of the soil in turf lawns. That leaves clover open to winter damage, especially in the coldest part of its range. Of course, winter damage tends to correct itself as clover fills in over the summer thanks to its wandering runners coming from surviving plants. However, empty, muddy patches in spring will be quite visible in a monoculture while in a mixed lawn you won’t notice any unequal growth nearly as much.
Installing a Micro-clover Lawn
You can sow micro-clover any time the ground isn’t frozen, but ideally at a season when the temperatures are cool and rain is abundant. That’s usually in the spring between 2 weeks before and 4 weeks after the last frost or in late summer or fall up to 4 weeks before the expected arrival of the first fall frost. In colder climates, seeds sown too late in the fall may not germinate until the following spring.
A location in the sun or partial shade in soil that retains some moisture is ideal. The soil does not need to be rich, since clover supplies much of its own fertilizer through the bacteria that inhabit its roots. Micro-clover tolerates drought once established, but still, it’s not suited to hot, arid climates. It can be successful in USDA hardiness zones 2 to 10 (AgCan zones 3 to 10), especially where nights are not unbearably hot.
To overseed an established lawn with micro-clover, rake well, scratching the surface a bit so the seed can penetrate. Or top dress to add a layer of fresh soil it can root into. Sow at a rate of about 1/4 to 1/2 lb per 1000 ft2 (225 to 250 g per 90 m2). Keep the soil moist until germination.
To start a new mixed lawn, prepare the soil by weeding it thoroughly and working the soil to a depth of about 3 inches (9 cm), then rake to even it out, removing and stones and debris as you go. Ideally, you would then also top-dress with ½ to 1 inch (1 to 2 cm) of good soil, although that isn’t absolutely necessary. Mix 5% of micro-clover seeds into the original grass seed blend and broadcast sow. Rake lightly to work the seed in, then keep the soil moist until germination.
To start a clover-only lawn, follow the general recommendations for a mixed lawn (previous paragraph), but sow only clover seed. Sow at the rate recommended by the supplier or at about 1 to 2 lb per 1000 ft2 (250 to 500 g per 90 m2) of surface area.
The first year, water your micro-clover lawn in times of drought. There will be few to no flowers in the first year. If there are places where the lawn appears sparse, just be patient. Usually clover will cover it with its creeping stems quite quickly. If not, reseed those spots lightly.
When the plants reach 4 to 5 in (10 to 12 cm) in height, mow to 3 in (7 cm) or less. They’ll react by producing the dense carpet of tiny leaves that micro-clover is famous for. It may be necessary to mow another 2 or 3 times during the summer depending on whether you tolerate a slightly uneven lawn or insist on the effect of a perfectly flat carpet.
Simply leave the clippings in place: rich in nitrogen and other minerals, they help fertilize the lawn.
From the second year on, mow as explained above and water in case of severe drought, but otherwise let Mother Nature take care of your micro-clover lawn. The lawn will need less fertilizer, and in particular nitrogen fertilizer, than a lawn composed solely of grasses.
If your micro-clover thins out in places over time—and that may happen after a few years, because the clover doesn’t live forever—, resow as explained in “overseed an established lawn” above.
Micro-clover: a new way to develop a beautiful lawn.
Article adapted from one appearing in this blog on May 11, 2016. Unless otherwise mentioned, photos from Gloco.