I often find the same 'supposed to' mind set in gardening. But I just don't think there are as many 'supposed to's' in life or gardening as we think there are.
Aside from giving these Japanese hollies some soil acidifier to help counteract the alkalinity of the concrete, I completely neglect them. The blue 'President' clematis, however, is a bit pampered. (Spring 2012)
You are supposed to use evergreens when landscaping your front yard.
Who made up this rule? While evergreens do give you winter interest and a beautiful canvas for snow, if you're lucky enough to get any, it's your yard. Do what you want. I have a row of evergreen Japanese hollies next to my front walkway that were planted by the builder nine years ago. Tough as steel, they are never given supplemental water and thrive in a small sliver of soil between the front porch and walkway. But I didn't keep them there because I was supposed to. I kept them because they look good and never died. The rest of my front yard plantings are flowers and deciduous shrubs.
I'm growing roses mixed in with perennials! What is wrong with me?? (Spring 2012)
Westerland climbing rose is super cold hardy and very disease resistant.
Roses lined up like soldiers look weird. I know that's just my opinion, but it's such a pervasive design approach that it's come to be considered an absolute rule. I had someone comment this summer that I wasn't 'supposed to' grow my roses mixed in with other plants. But my garden follows my rules and my roses grow happily amongst perennials.
My monarda patch is full of conflicting colors. I picked my monarda based on how tough and disease resistant they are. I don't care if they clash. Neither do the hummingbirds. (Summer 2012)
I look forward to these geum every spring. With their bright colors and ruffled petals, they remind me of Spanish flamenco dancers. (Spring 2012)
Colors aren't supposed to clash.
As guidelines go, this is a good one. But what I consider cheerful, might be migraine inducing to you. I love pink and orange together and have plans for a big pot of perennials that will include orange coneflowers, purple liatris, and red silene. It's a party in a pot! Chose your color combinations based on what makes you happy and emotionally satisfied. It doesn't matter if no one else likes it. It's not their garden.
I never know where tradescantia will pop up around my garden. Since it's a self-seeder, it usually just shows up in groups of one or two, although sometimes it brings a crowd. (Summer 2012)
My potted perennials often contain just a few of each variety. (Late spring 2012)
Always plant in groups of 3, 5, or 7
Unless you find a plant you love on the sale table and they only have one or two. I have a friend who purposefully adds plants in ones and twos just to add a sense of chaos to her beds. She doesn't want a super neat garden and throws in plants just because she loves them, regardless of the overall scheme. The result? A colorful jumble of a garden that is happiness personified. However, when trying to attract pollinators large plantings work better than smaller ones.