For waves of bright colour consider planting bulbs in clusters and groupings. Since bulbs generally flower before your perennials you may wish to plant some around these plants as they will have the space and time to flower and finish their cycle before your perennials are in full bloom. Do remember to let the foliage from the bulb flowers die off naturally as this is the way the bulb gathers strength to bloom for the following year. Not all bulbs are for spring blooming so insure you read your bulbs packaging so that you get what you are looking for and that you can companion plant based on the the blooming period of the other plants already in your flower bed.
You can even get a little creative and perhaps plant some bulbs around some outcropping of rocks. Try some crocuses in your lawn. If you are not happy once you see the results of your plantings you can always dig up the bulbs once they have flowered and their foliage has died off and plant them in another location.
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