Category Archives: Cardboard Mulch

Help! The Alliums are Rising

When we moved in last April, things were pretty skimpy bulb-wise around here.  A daffodil here and there was about it. Being in a flood plain, I understand bulbs could have a chance of rotting, but there’s some high ground. So this fall I planted bulbs:  Daffodils, Tulips, Muscari, Crocus, Iris, Ranunculus, Siberian Squill, Wood Hyacinths, Lily of the Valley and, of course, Alliums – 36 of them.

Now it’s December and the bulbs have stayed under their blankets, except those Alliums.  My planting method, along a weedy crabgrass side of the house, was dig holes for the bulbs and leave the grass alone. Step two was cover the bed with a layer of cardboard (we had so much of it from the move) topped with Leafgro (a truly divine concoction of mostly composted leaves). I figured the bulbs didn’t need to see the light of day until spring when the cardboard would have done in the grass and started on its way to composting itself. The Leafgro would be frosting on the cake.

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Cardboard over Alliums

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Added Leafgro

But this month those Alliums started rising, some pushed up the cardboard and others actually broke through. It was a terrible sight because historic torrential rain had washed the Leafgro off the cardboard. The solution – more Leafgro to the rescue.  Now I’m wondering, will the Alliums continue growing and get zapped by frost? Will they flower? What will they do next summer when I want those stately balls to do their stuff?

So there are two topics here. What’s the deal with the Alliums and is cardboard a suitable mulch? Everywhere I search I’m told Alliums should be planted in the fall and they can be grown by dummies.  The other news is there are varieties in many colors, sizes and shapes that can carry the blooms from spring to fall. Next year I’ll search out more provided the Purple Sensation and Starlight Blend I put in this year manage to thrive.

The question of cardboard mulch turns out to be a controversial topic. Who knew? What I already know is even in six weeks my cardboard broke down sufficiently for bulbs to come through.

The Garden Professors website has many reasons gardeners should not chose to use cardboard. On the other hand, Margaret Roach on her website A Way to Garden has a detailed explanation of how to properly make a bed with cardboard mulch.  The take away is you must not put down cardboard and forget it. You must make sure it doesn’t dry out or the soil underneath will become a wasteland. After the cardboard has done its job of smothering unwanted vegetation it must be reevaluated. Will it integrate with the soil or must you pull it off and consign it to the landfill. As always, attention must be paid.