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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

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J. Musser
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cockypup
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3 Answers3

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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.

J. Musser
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    Thanks a lot! I managed to remove most of the big concrete slabs because I did want the bulbs to naturalize not just to bloom one year. I know tulips are hard to naturalize but I will try because these are a special gift. I appreciate your answer, though. I did not know that, if I want them to bloom just one year, then less depth is OK. Very helpful to know that. – cockypup Nov 03 '14 at 15:46
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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.

TeresaMcgH
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  • I will definitely raise the bed next year but this year I don't have time. The soil will freeze soon so I need to get the bulbs in as soon as possible. – cockypup Nov 03 '14 at 15:41
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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.

Bamboo
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  • Actually, in similar situation to this, even though the soil was clay, the shallow area over the concrete dried out far faster than the surrounding soil, so much so that it was actually a pain to water the plants so often. – J. Musser Oct 30 '14 at 15:58
  • @J.Musser - aye, that may be so, but we're talking about winter in Toronto - cold, probably rain or snow, followed by a lot of melt water, so drying out is hardly a risk. – Bamboo Oct 30 '14 at 17:45
  • Actually, they get 30-40 in./yr., which is less than me, and temperatures below -15 or -20 F. are unusual. Basically, not much worse than my climate, except for the temperature. And the average freeze times are from mid sept. to mid May. Only slightly longer than here. – J. Musser Oct 30 '14 at 17:56
  • Very interesting - but I'm standing by my answer! – Bamboo Nov 01 '14 at 11:20
  • Thanks for the drainage comments. I managed to remove most of the foundation so the slabs are not there anymore. The soil under the slabs is mostly clay which is bad for drainage but has some pebbles, which is good for drainage. I will add some organic matter (aka broken fall leafs) to improve the drainage. – cockypup Nov 03 '14 at 15:43
  • @cockypup - good news you got the slabs out - a layer of grit beneath the bulbs might help, if you're not intending to break up the clay soil. – Bamboo Nov 03 '14 at 16:14