So, tell me about your understory...

[glacierchick]

...planting that is.

Backstory: I have previously done a lot of gardening of the pot on patio or handkerchief sized urban garden variety. We've just moved into a new (rented) house with a much bigger garden, it's been a bit neglected and seems to have had trees and shrubs planted almost at random in the beds with a largeish lawn area in the middle. As we are renting and will probably only be here a couple of years I don't want to spend too much time/money but do want to get it looking nice. There are masses of spring bulbs, many of which are too congested so haven't flowered, but there are no real summer plants aside from the shrubs already in.

I have a plan to put in lots of perennials and self seeders and we've already planted lots of summer bulbs in the few clear areas, but I'm really wanting to know what I should put around the bulbs, shrubs and perennials as ground covering type plants. Any ideas?

We also appear to have beds infested with ground elder, brambles, japanese knotweed and creeping buttercup. So something that can compete with that would be useful (ho ho ho).

How about vinca minor (avoid vinca major - it is the most thuggish of thugs...)? I find the one with variegated leaves and lilac flowers does best for me. The plain leaved one with mulberry coloured flowers is a bit of a wimp. Or hardy geraniums? I bought seeds of a purple flowered geranium pyrenaicum (from Plant World) a couple of years ago, and the resulting plants have self seeded everywhere and are lovely. They are flowering already abd will do so until November in my garden.

What kind of spring bulbs? If they are bluebells and grape hyacinths they will swamp any perenials you plant out and stop light getting to them so they may not survive next year. You're better off plating your perenials into pots and then putting those into the flowerbed after the bulbs have died down and lifting them out again (still in pot) for the winter. I do this with my echinaceas but a coupke of years decided to put them into the ground and nothing coming up the following spring!

Are you sure there aren't any summer plants? They may only just be starting to come through, especially late flowering bulbs or perenials. If someone has spent time and effort on spring bulbs, shrubs and trees it seems unlikely they neglected the summer unless they simply filled it all up with annuals.

If you're not going to be there long have you tried sprinkling some annual seeds like love in a myst/nigella or nicitiana) in the gaps? Or get a big pack of petunias and bizzy lizzys and throw those in for some colour once the chance of frost is gone.
Is there enough sun to try sunflowers? You still have time to start things off from seed now.
If you must go for perenials then I suggest scabias or hardly fushias. And yes the hardy geraniums suggested above are good too.