Can I plant tulip or daffodil bulbs in 6" of soil, over a concrete foundation?

Question

I have recently bought a house and I was planning a small tulip patch. I dug my ideal area on the backyard, 6" deep, just to discover I had chosen the spot where an old foundation had been covered with soil :(. It is right at the 6" depth that the tulips need to be planted at.

Can I plant them on top of this concrete foundation, maybe less deep (5" or so) with a bit of soil under them (1")? Or should I just get over it and choose a different spot?

How about daffodils?

I live in Toronto, Canada, in USDA hardiness zones 5/6

Answer 1

Tulips do best when planted deep, like 8 inches, for best perennialization. Daffodils, on the other hand, will spread much faster when planted at 3-4" deep. Now, this is for the purpose of perennialization, to make sure the plants return each year. Bulbs need root space as much as other plants, long term.

If it's a one season thing you are doing, They will be fine planted as you have depicted in your question, about one inch from the bottom. Flowering size tulip and daffodil bulbs contain enough food for one successful flowering period, in confined conditions, but will not build up the stores to the point where they will maintain themselves/multiply in coming seasons, unless they have a normally deep garden soil.

So I would say, if this is one season, go ahead and plant (keeping in mind shallow soil will dry out fast, and need to be watered very frequently), but if you want them to come back, choose a suitable spot.

Answer 2

The bulbs will need more root space than just planting them above the concrete will allow. Can you raise the bed more? If so, then this might work. If not, then another spot would be far more suitable.

Answer 3

Put them somewhere else - another factor that's very important, apart from the ones already mentioned in other answers, is drainage - bulbs rot where drainage is poor, so I wouldn't even plant them there for one year. Tulips particularly dislike wet soils.