building up a flower bed over bulbs and perennials

by Kim P.
(Austinburg, OH)

I have an established flower bed where crocuses, balloon flower, daffodils and tulips grow back every year. The bed is in need of building up and typically I would add more topsoil. Can I, instead, add lasagna layers, after the plants have died back? Will the bulbs and plants grow back through the layers next year? Or will they get smothered with not enough air and light? I need to add about 6 inches or more of material, either topsoil or layers. I would rather do the compost layers, since that would be cheaper.

Comments for building up a flower bed over bulbs and perennials

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Sep 24, 2010
Composting over perennials and bulbs
by: Megan

The recommended level of compost to add to perennials is up to around 7.5 cm (3"). The idea is to put the compost, manure, mulch or lasagna layers down during dormancy in autumn or winter, and it will rot down nicely thereby reducing in thickness and providing fertilizer for the emerging bulbs or plants in spring. A 15 cm (6') lasagna layer should be OK as there is a lot of air space and it will rot down nicely in a few months.

If you actually wanted to build up the permanent level in your perennial patch by 6 or more inches, then yes, the plants may have trouble pushing through to the soil surface without giving up. Too deep planting of bulbs and perennials can also make the flowers appear on the surface without any stems showing, or more often the plants just grow leaves and don't flower at all.

It could be that your plants are shallow planted to begin with and thus building up the soil level will do no harm, but if in doubt and depending how practical it is for you, it may be best to dig up and transplant some or all of your plants after composting.

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