Perennial Planters for Patios in Zone 6
Updated January 4, 2024
Back when I was performing small landscaping projects in Chicago (2015-2016), one of my clients had texted me that he’s “not getting any bees” in his urban roof deck oasis in the neighborhood of Lakeview. He wanted me to plant flowers that would bloom over a long period of time and also attract bees and butterflies. His determination to attract bees to his patio was endearing and I jumped at the opportunity to help him with this quandary as most city people balk at the sight of bees and bee-like creatures buzzing above their personal space.
In this post, I’ll show you which planters we chose for his exposed rooftop garden, how to fill planters with soil, how to insulate planters over winter, and the best perennial plants to use for outdoor, year-round planters in Zone 6. If you’re looking for what plants to grow in planters in a cold climate, this post will be helpful for you.
how to choose a pot for perennial plants
Perennial plants will last for years in containers, but only if they have enough root space to establish themselves. They need enough room to grow strong roots, along with enough insulation from the surrounding soil to stay alive through winter in a planter. Your planter should be at least 20″ tall and 12″ wide (the wider the better).
There is no “perfect” planter for perennial flowers in cold climates. There are some really nice double-walled planters made by Crescent that are on the more expensive side but will last forever and will protect your plants over winter better than single-walled planters. These types of planters are used in many retail and restaurant spaces.
best outdoor pots and planters for cold climates
Putting together a perennial planting in a high-quality planter is the best chance for busy urbanites who want to fill their space with plants but have little time to fuss over their garden. With the right size planter, the right type of soil and hardy perennial flowering plants, you can invest once in a planter and enjoy it for years to come.
For my client’s rooftop patio in Chicago, I sourced these heavy duty, insulated planters on Amazon. There is little to no assembly required for these planters and they are very lightweight and easy to move around on a deck or patio.
I would also recommend these planters as excellent choices for perennial plantings:
what kind of soil to use for a planter?
Just like an in-ground vegetable or flower garden, your cut flowers will only be as healthy as the soil you plant them in. Flowers require organic matter and fertilization very similar to that of fruits and vegetables. That said, it is important that you don’t buy the cheapest potting soil at the store.
Related: Regenerative Agriculture Books & Podcasts
When shopping for soil for your planter, you’ll want to buy POTTING soil, not top soil. Potting soil is mixed with airy vermiculite (the white flecks in the soil) which will help the roots of your plants breathe in your planter. If you use top soil, or soil dug from your garden/yard, you should buy a bag of vermiculite and add it to the soil so it does not become compacted and dense.
best potting soil for perennial plants
Bagged soil is not made equally. For your efforts, and for the health of your garden, I recommend you buy a good brand of potting soil so don’t have to go back and replace it every single year or keep fertilizing it throughout the season.
Related: The Reasons Why Synthetic Fertilizers like Miracle-Gro Are So Bad for Your Garden
The best potting soils, already full of organically-derived nutrients and trace minerals, are:
organic fertilizers for perennial plants in pots
Fertilization is typically not required to keep perennials blooming when they’re planted in the ground — but it is important to fertilize everything you have growing in a planter. The difference is, when perennials are planted in the ground, they are able to sink their roots deep into the earth to mine minerals and nutrients. There is also a more robust presence of soil microorganisms (bacteria, fungi) and macro organisms (earthworms, beetles, etc) to help shred organic plant matter and provide nutrients for the plants.
When you use potting soil, your plants are restricted to whatever nutrients are in the potting soil. This is why it’s important to buy high quality, organic potting soil that is full of minerals and nutrients already. There are, however, a few things I add to potting soil even if it is the highest quality.
Alfalfa Meal — I like using alfalfa meal (or alfalfa pellets) mixed into potting soil to add organic matter for microorganisms to consume throughout the season. The alfalfa meal will also add nitrogen and lots of trace minerals to the potting soil mix.
Mycorrhizal Fungi Inoculant — I add mycorrhizal fungi inoculant to every single plant hole, during planting. The inoculant is full of beneficial fungi that will help plants find nutrients and water, and help them grow bigger over time. Learn more about myorrhizal fungi in this post here.
how to take up space in the planter: Fill Your Planters 50-75% With Something Other Than Soil
If you source planters that are tall and extra deep, you might consider filling the bottom part of them with something other than your expensive potting soil. Perennial roots will grow best with 12-18 inches of potting soil depth. Anything deeper than that, you could fill with empty plastic water/pop bottles or milk jugs, bubble wrap, or any similar type of plastic waste in your recycling bin, simply to take up space. You’ll also be able to move these around easier once they’re full of soil and plants.
Related: How to Start a Sheet Mulch Garden
the best perennial flowers for pots in zone 6
My favorite perennial flowers for an outdoor planter are the ones that are super hardy and come back every year without fail. For USDA Growing Zone 6, my favorite perennial flowering plants for planters are:
Yarrow — yarrow is unfailing and will come back strong and fill out your planter every year!
Echinacea purpurea
Clematis Vine
Salvia — make sure you source perennial salvia
Lavender
Bee Balm / Wild Bergamot
Sage, Oregano, Chives, Mint, Lemon Balm (what a lovely perennial herb planter this would make!)
Do you have to water perennial flowers in a pot?
Yes. Most perennial plants are known to be drought tolerant when planted in the ground, but in a planter, they will dry out quickly on a hot, sunny day. I recommend watering them every day on hot days, just like you would your annual plants.
how to insulate planters over the winter
Insulating your planters for the winter is an optional step — if you have spare blankets or burlap, you could opt to use it to cover your planters over the winter. I recommend doing this if your planters are completely exposed to the elements all winter (although I will say it’s totally unnecessary to do with yarrow!) Alternatively, you could move your planters inside a garage or other covered space.
I also recommend that you wait to cut back your perennial plants until spring. The overhead growth will help protect them from harsh cold snaps throughout the winter months. Plan to cut your perennials to the base of the plants when you begin to see new growth spring forth, in March or April.
peace, love, and long-lasting planters for all,
Fran Parrish
