Gardeners - a bulb question

I’ve got two flower beds that I carefully built, gently planted full of bulbs… and seeded grass in a bare spot nearby and got the beds full of it. My question is, if I try killing the grass with black plastic in the heat, will my bulbs under the surface be harmed? They’re daffodils and crocuses, mostly, with a few hyacinths. Alternately, would a herbicide harm the bulbs?

Nobody? Please?

If the bulbs are completely dormant (no growth showing), you should be able to spray the grass with Roundup to kill it off without damaging the bulbs.

If there isn’t that much grass, you could pull it by hand or superficially hoe it.

Why do anything? One of the best things to do with bulbs is plant them more naturalistically, in shaded spots in the yard under the grass. You don’t end up with dead space when the bulbs are not in bloom and when they do bloom you have an excuse to not mow until they are finished. My brother used this technique a lot in his gardening days. He thinks bulb gardens are unsightly most of the year. He is also a big fan of low growing ground covers of any description in flower beds- mind you ther are lots available here.

I would not do Round-Up – I killed some crocus bulbs I had under the lawn because I forgot they were there and did a weed-and-feed thing in the fall.

If the bed is nothing but bulbs, yeah, leave the grass there and let it fill in – but I for one have a tiny garden, and I go to annuals after the bulbs finish – I can’t afford a bed that’s only happening one season.

Weed killer works. Warning: PDF files.

Weed Control in Ornamental Bulbs. The original 1999 study.
Weed Control in Ornamental Bulbs. The followup “plantback” study in 2000.

Basically, as long as you wait until the foliage dies down, it looks like you ought to be OK.

My concern with using black plastic would be that yeah, it would make the soil too hot–you’re already in SC, with what are basically cold-loving bulbs. Found this:…Many [daffodils] will not perform well in warmer parts of the state.” Get 'em too hot, they’re not happy, I guess.

Edging (either plastic or metal) works pretty well, too, although you have to get down there on your hands and knees with a trowel and really bury it, at least 6" deep, and you have to leave some sticking up above ground level to keep the grass from sending runners over it, and then it’s a PITA to mow because you can’t get the mower up on the metal or plastic edge, so you have to do a lot of trimming, unless you install those mower-edge brick pavers. Anyway…punching a small slit into the ground with a spade and then tramping the edging in with your shoe won’t work for longer than a few weeks, in my experience. And then you have to exercise constant vigilance, because the soil level on the grass side will raise up as time goes by, and if you’re dealing with Kentucky bluegrass, it’s just sitting there waiting for that extra millimeter to send runners over the edging, and you go out there and you’re like, “Where’d my edging go?” It’s under the grass, honey.

The trapped heat won’t harm the bulbs. Alternately, you could cover the the grass with five or six layers of newspaper and cover the newspaper with mulch. That will kill the grass, too, and the newspaper will just break down into the soil. (They say not to use newspaper with colored inks because they contain toxic compounds, but if you’re not going to eat your daffodils, I don’t think you’re running much of a risk.)

'Cause it’s a flowerbed that flanks my front walkway and it looks like crap. I’m trying to find something I like that’s a shortish blooming groundcoverish thing that can take care of itself while I worry about my perennial beds, but the grass took over first.

It’s not an edging issue - this is grass from seed because I’m a big dummy.

I’ve had a hard time keeping it mulched because it’s a raised bed (lasagna bed, actually) and only about two feet wide, so the mulch is always falling off. This is how I got such a lovely grass garden there. Pulling is an exercise in futility; I’ll die of heatstroke before I get this grass out by pulling it. I’m afraid to hoe because of the bulbs.

I may try newspaper; I’d thought about cardboard but it’s probably too stiff for these beds in this configuration; newspaper, on the other hand, maybe. The beds are less tall than they used to be, too, so mulch may possibly stay on them this time. At the top of them, I’ve got some Stokes asters and dahlias, and at the bottom a few creeping phlox that I’m trying out as a nice weed-retardant groundcover (site of my slime mold featured in another thread), but I could work around those. Seriously, we’re not just talking about a little grass here - nothing’s growing in the bare spot in the lawn, but the grass in the bed is seriously lush.

Smothering grass/weeds with a few layers of newspaper (topped by mulch) does work fine. I laid down anywhere from four-eight sheets on a shrub bed with hardwood mulch on top last fall, and the newspaper has broken down (but the grass is dead). Small numbers of weeds will germinate in the mulch, but it’s not a major problem.

Roundup is a contact vegetation killer and does not soak into the soil to target roots/bulbs. As long as it’s used as directed dormant bulbs should be fine.

Try vinca (aka periwinkle, aka myrtle). Pretty purple flowers around Easter, then nice glossy foliage the rest of the year. Spreads nicely.

Everybody’s got vinca around here, though. I was just wondering, come to think of it, if there’s a lower-growing lavender I could try there. Then I could put less water there, which is bad for the bulbs, have something fairly evergreen, still see the bulbs when they come up but hide them the res tof the time. It would have to be a pretty low type, though, and I probably still wouldn’t see my crocuses.

I’m trying out the creeping phlox, like I said, but it’s doing much better on one side of the walkway than the other.

Don’t do periwinkle unless you want it EVERYWHERE. Spreads is the very word.

Also, a groundcover that blooms in the summer or fall is better than one that blooms in the spring, because I’ve got the bulbs for spring color.

I’ve never tried this, but I always saw it in the Whiteflower Farm catalog, namely, planting daylilies over bulbs. The theory is the daylily foliage doesn’t emerge early enough to hide the crocuses and the like, but when it does emerge, it does a dandy job of hiding the daffodil foliage.

I know a lot of people are “meh” about daylilies, but there are some gorgeous cultivars out there that in now way resemble them orange thangs that grow in the ditches.


no way resemble

Fall bloom – plumbago, which has lovely cobalt blue flowers in the fall, plus foliage that turns a rather striking bronze. It totally dies back in winter, though, unlike most groundcovers, so that may be a dealbreaker. (Hm, or at least it does here – dunno about down in your parts – what are you, zone 4?) It works well with spring bulbs though.


I can’t begin to imagine why I was subtracting numbers and not adding them – should have said “what are you, zone 8?”

Yeah, I’m zone 8. I looked at plumbago, but then there’s the die-back thing. I wouldn’t mind, except that I need to choke out the weeds and down here, weeds grow year-round. I don’t know anybody who grows it - might have to ask the master gardener I work with if it keeps some green in the winter.