The gravel garden on top of my flat roofed garage was originally planted up 10 years ago, and after the hottest driest Summer I can remember.

If I were to do it again, I’d plant it differently. Instead of planting out a grid, I would plant something more free-lowing within one large bed. If I could force myself to be disciplined enough (working against my nature in a major fashion) then I would focus on fewer plants and just police them. In particular, I’d allow the gravel to show through more in between large colonies of the more successful plants.

In this “what might have been world” the entire bed would be underplanted with alpine bulbs, groups of crocus, iris, narcissus and alliums, planted in groups randomly under the gravel. Some of the bulbs planted over the year have now started to come up blind, without flowers, so maybe next spring I should take some time to weed those out of the bed.

Then I would plant out a few of the thugs:

• Armeria maritime ‘Glory of Holland'(thrift) (Spring)
• Aster ericoides prostrates (Autumn)
• Erigeron Mexican Fleabane (Summer)
• Geranium cinereum “Ballerina”
• Satureja spicier (Autumn)

And I would try to make myself pause to see how those plants started to colonise the bed and think about when they flower and where there might be gaps

& I could just remove the remaining wicker hurdles marking out the grid and try to encourage the bed down a more free form structure with these plants anyway – it’s not as if they aren’t doing their very best to own the space, with no help whatsoever.

Of the non-thuggy plants, which ones am I attached to enough to want to referee and to protect enough to weed out an island of gravel around them?

Maybe the following:

• Dianthus ‘Gold Dust’ which has gold flecks on a deep red flower and forms a clump
• Helianthemum ‘Beech Park Red’ a miniature rock rose.
• Penstemon pinifolius which is a sort of orange-red flower which appears just when you want it and always seems to last forever.
• Phlox subulata ‘McDaniels Cushion’ – a useful cushion of beautiful flowers that seems to hold it’s own without spreading everywhere
• Pulsatilla vulgaris* the basque flower for Easter – lovely flower that just cheers the soul.

But that’s considerably fewer plants the i can see up there at the moment – maybe I just need the confidence to strip down the bed from the current over-abundance.

Obviously I’ve added plants to the original planting list, just because I’m the kind of gardener who can’t stop themselves relentlessly over-filling but in general I’m lazy enough to have tried to stick to the original plan. It’s probably time to take stock.

Some just died a death in the first couple of years, presumably because it was too dry rather than too cold through the Winter, which is usually milder in London. These are ones to avoid when looking to re-plant obviously

• Sedum cauticola
• Sedum sexangulare
• Sempervivum ‘Greyfriars’
• Sempervivum ‘Jungle Fires’
• Draba rigida var imbricata compacta

Some have held out for years but have just died (or disappeared, the dodecatheon seems to pop up every other year) in the last year or two, so may be worth considering. A friend commented that all plants have a finite life and we shouldn’t stop ourselves from re-planting them unless we’re actively looking for a change.

• Dianthus ‘Gold Dust’
• Dianthus ‘Whatfield Cancan’
• Osteospermum ‘Irish’
• Dodecatheon pulchellum ‘Red Wings
• Erysimum ‘Emms Variety’
• Erysimum ‘Parkwoods Gold’

Some of the plants whilst surviving are just at risk of bullying by the thugs, usually less if they flower earlier*.

• Arenaria purpurascens
• Alliums, crocus & iris
• Helianthemum ‘Beech Park Red’
• Gentiana saxosa
• Leucojum autumnale
• Oxalis enneaphylla ‘Rosea’
• Penstemon pinifolius
• Phlox subulata ‘McDaniels Cushion’
• Pulsatilla vulgaris*
• Rhodanthemum hosmariense
• Omphalodes cappadocica

But some of the plants took off and are still doing their very best to take over the entire roof and whilst it’s always satisfying to see things that I’ve planted survive (yes, I really do set the bar that low) they often turn out to be the plants we love least.

• Armeria maritime ‘Glory of Holland'(thrift)
• Aster ericoides prostratus
• Erigeron Mexican Fleabane
• Festuca Glauca (blue grass)
• Geranium cinereum “Ballerina”
• Phlox subulata ‘McDaniels Cushion’
• Satureja spicigera

But then there are the ones that I decided I just couldn’t bear and ripped up almost as soon as they were planted:

• Campanula x pulloides