What about weeds? And ground elder?
Only a few weeds will germinate in a shrub bed if the shrubs are planted closely enough together and mulched if necessary. You can always hoe between the branches to disturb any weeds which still manage to germinate. But be careful: Some shrubs, such as hosta for example, have roots which are very close to the surface and can be destroyed by hoeing.
Do you have to trim shrubs?
There is no need to trim for trimming's sake in a summer garden. If you want to avoid seed formation and self-sowing, remove the blossoms by trimming them back. Delphiniums, wolfsbane, remote sage, catnip and marguerites can be encouraged to grow by removing the blossom stems at an early stage so that they regenerate and bloom again in autumn at the latest. I let shrubs that retract during the summer and wilt in good time, such as bleeding heart, draw back before I remove the wilted leaves - even if they don't look that pretty whilst they're drying out. However, allowing plants to throw off their leaves strengthens them as they enter their resting phase.
For more garden pleasures: Divide up your shrubs
In later summer (depending on the weather from as early as the start of February), you can take up and divide numerous shrubs, especially dwarf iris or marguerites, for example, in order to revitalise them. Only very long-lasting shrubs such as peonies are best left in one place for years.
The time for dividing shrubs is also the time for sharing shrubs: Present garden-loving friends with any shrubs you do not want to keep yourself. As well as increasing the variety of shrubs in each person's garden, this brings a little joy to everyone and makes friendships even stronger.
How to get your summer flowers to bloom even better
If you always follow the information on fertilising and watering flowerbeds containing annual summer flowers, you have already done the most important thing because a consistent water supply is particularly vital for long-lasting flowers. For varieties which do not handle lime so well and require a lot of iron - such as petunias, hebes, cabana whites, and blue daisies - iron deficiency symptoms may appear (yellow younger leaves, leaf veins still green at the root). This is particularly likely in very limey soils and when using hard water. Simply treat the plants with a ferrous feed from a specialist retailer as per the instructions.
In August, some plants (e.g. the fairy fan-flower or older varieties of petunias) may experience a blooming phase and other plants may have disappeared completely (e.g. lobelia, sages) by the time you come home from your holiday. Dead plants are best removed from the bed. Plant up the gaps with meadow herbs, grasses and bushes, for example, to move from a late summer atmosphere to an autumn feel. In addition, in the case of all summer flowers and especially fuchsias, lantanas, geraniums, nemesia, diascia, fireball, and bidens golden eye, do not let the plants go to seed because this switches their hormones and they produce fewer flowers!
Making sure you have some every year: Biennials
Remember that biennials have to be sown early if you wish them to grace your garden the following year. This includes sweet william, smokey fennel, foxglove, blueweed, rose campion, milk thistle, mulleins and some gentians.
You also have to sow pansies and horned violets for the coming year now; do not forget the complementing large-flowered garden daisies and the forget-me-nots.