My balcony garden design for summer, 2021

The situation with balconies facing west, in zone 5

We live in an apartment on the 13th floor in downtown Minneapolis, overlooking the Mississippi river. It is a dynamic place to live, but it does not have the backyard garden that I enjoyed for 25 years before moving to an apartment. However, there are ways to incorporate gardening into high-rise life. Although we don’t have a backyard anymore, we do have an outdoor balcony which is 25 feet in length and inset into the building by 8 feet. Over the past three years of growing plants on our balcony I’ve learned a few things.

Mainly, the plants on our balcony suffer from west facing afternoon sun, and baking temperatures in the summer, often up to 125 degrees F. On the other extreme, we live in zone 5 where the roots of any plant left on the balcony over the winter will freeze solid in their pots (temps often -20F). Even in large pots, no plant will survive if their roots freeze. Therefore all plants on the balcony I consider to be annual plants, and must be able to tolerate heat, dry conditions, and strong winds of the non-winter months. This is a tall order for any plant species.

The goal: plants to provide summer and winter interest on the balcony

To contrast and soften the hard edges of a concrete and metal balcony, I’ve attempted to create a grassy hedge which will survive the wind and heat. I chose 12 inch (3 gal?) planter bags for ease of use, and set them inside fiberglass boxes (48”x12”x12”) to create a uniform clean looking profile. There are 3 bags to each of 8 boxes.

In attempts over the past 2 years, I have tried a a couple varieties of grass species. First in 2019 I tried blue oat grass, but it failed to grow in the harsh conditions of the balcony. The next year in 2020 I tried native Little Bluestem grass, but it also failed to grow larger than the initial starting pot. Finally, in 2021 I tried Juncus inflexus - hard rush, native to Europe - which I found at a large local nursery. The variety looked very healthy in the nursery pots and the specifications indicated sun and drought resistance. The price was very reasonable to the point I thought there must be some mistake…but no. Yahtzee! 

I calculated that I would need 72 plant pots, each about 6 inches in diameter. It took two trips to the garden center to transport them in my little Honda Fit.

The equipment 

I have eight 4-foot fiberglass planter boxes lined up along the balcony’s railing. The boxes are 12 inches deep and 12 inches wide. I decided grow bags would be easier to manage than filling the boxes entirely with potting soil. The bags will dry out over the winter, making it easier to remove the old plants and slot in new ones.

Each of the boxes will hold three grow bags. I chose grow bags which are 12-inches in diameter and 12-inches deep (5 gallon size). Each bag will hold 3 of the plants, totaling 72 plants in the 8 boxes. I used organic potting soil to fill in the gaps in each bag. Rather than have the bags sitting in the sometimes-wet bottom of the box, I raised them up onto upside-down plastic garden trays which I scrounged from a local garden center for free (I needed 16 of them, or 32 of them doubled up for added strength). The boxes also have emergency drainage holes in case a typhoon drenches the balcony filling up the boxes with rain water. I drilled each hole about 1-inch up from the bottom of the box, at the end of the box so that the holes aren’t visible when the boxes are lined up in place. 

We set up an irrigation tank at the very end of the balcony, next to a power outlet. Tubing from the tank was threaded to each cloth planter bag. The tank holds 15 gallons of water, which we had timed to dispense twice a day. The tank had to be refilled every few days to keep the soil moist. Occasional rains helped to keep down the need to refill the tank. At the height of summer, the plants consume 10 gallons of water every day. Yes, I have to lug three or four pails of water from the kitchen to the 15-gal water-tank on the balcony…every day or so. Even in an apartment, there is always something to do in the garden.

We placed a small aquarium pump in the tank and connected it to an internet-controlled timer. The timer allowed us to set the pump to dispense water for 15 minutes, twice per day. Of course, we could adjust the timing as needed. But, I found the initial setting was about right to keep the soil damp - but not wet - to touch.

Overall, I was happy with the result. This species of grass stood up against the strong winds which get funneled up the wall of the apartment building. I enjoyed the movement of the grasses during the growing season and into the autumn and winter. The grass remained largely upright despite the snow, taking the edge off the hard angles of the City.

Irrigation tubes for each grow-bag, two dripper heads per grow bag

Juncus inflexus, drought and heat tolerant

Winter interest, the snowy grasses in December