Filling gaps between alliums

Question

At this time of year Thompson Morgan has a sale of 100 alliums for just under £6. I took the offer last year and have ordered 2 packs this year, so I have 200 allium bulbs to plant in the border.

The allium flowers look great, but, as I am very new to gardening, I am not sure how to cover the gaps between them in the border. What type of plants should I be looking for? Is ground cover (phlox) the correct type or will this impede the ability of the bulb to flower?

Caeruleum        0.5-1.0 m  10 bulbs
Neopolitanum     0.25 m     25 bulbs
Roseum           0.5m       20 bulbs
Sphaerocephalon  0.5-1.0 m  39 bulbs
Purple Sensation 0.5-1.0 m  3 bulbs
Mount Everest    0.9m       3 bulbs

It is this product 100 alliums.

I have also just found last years collection it was:

Caeruleum                      10 bulbs
Neopolitanum                   20 bulbs
Sphaerocephalon     30cm       44 bulbs
ostrowskanium                  20 bulbs
Purple sensation    90cm        3 bulbs
Christophii                     3 bulbs

Warning

Based on Bamboos input to this topic *neapolitanum * is actually a wild garlic and invasive likely should be avoided in a garden.

Just to be clear that this was NOT included in the pack by Thompson and Morgan, it was a typo on my part and they actually included neopolitanum. With a neo and not nea.

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Some pictures From last years planting: Unfotunately not found any picture from when they were all at there best, but the current set of late bloomers still have colour.

I believe the grey fronds are from an allium but now big show bulb has appeared. Or it is a weed. The big daisy type plant is a perennial that I did plant.

And an overall view of the garden (for Stormy) Alliums planted on the right along the side of the fence, roughly the middle third of the fence :

Answer 1

I'll take them in order then

A. caeruleum isn't hardy - you'll need to pot them and keep somewhere frost free over winter. A. neopolitanum (wild garlic) is highly invasive, and unless you're going to eat lots of it, I wouldn't recommend planting in the garden. ( I speak as someone who has spent over 20 years trying to eradicate the stuff from 2 different gardens) A. roseum - no problems, though I find it never actually comes up.

The others shouldn't be a problem, but all alliums like sun and free draining soil, so bear that in mind when planting, along with the height they'll reach. The other thing about Alliums is the leaves - these appear before the flowers, but by the time the flowers arrive, the leaves are already, or starting to, yellow and shrivel. This means Alliums are best planted in amongst other plants, so that their leaves are not noticeable, but the flowers appear above the surrounding greenery. The nature of most of them is to produce a flower on top of a long straight stem - the length of the stem varies with the variety, so that's an important factor to consider when choosing the ideal spot. Something like Purple Sensation can be planted between/behind, say, Lavender and Spiraea Goldmound, so you'll see the purple drumsticks arising above the two shrubs (one grey foliage, one yellow, so quite striking). Alliums aren't great for planting alone, they're always best mixed in with other planting in the border, because of the foliage habit.

There is one other lovely Allium missing from your list - Allium christophii - hardy, large pale silvery lilac airy round flowers, but with shorter stems than Purple Sensation. Deserves a place in every garden in my opinion!