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Array of multiple different potted plants on the ground and on a wooden bench by a window in a Yoderbilt Greenhouse.

How to Overwinter Geraniums

Mar 9, 2022

How to Overwinter Geraniums

This past summers-end was extra hard. I had grown every geranium plant either by seed or propagation in my greenhouse, and I wasn't ready to see them go. I had hundreds of them in a very select color scheme. The fall days were drifting in, and colder days were ahead. 

Close-up of a blooming geranium flower

I, like many others, have an obsession.

Geraniums. 

From the moment I planted that first seed, I had invested so much by way of time and care. I had enjoyed them immensely. So, I decided to give overwintering a try, and it exceeded all expectations.The initial preparation was time-consuming, but it was so worth it. And the overwintering process surprised me in how much joy those blooms brought—how much color, how much life, and all in the dead of winter. 

I started with one plan, but you will see how that changed course. It was a change that I never looked back on. 

Close up of multiple unpotted plants laying on a wooden table.
Multiple unpotted plants laying on a wooden table in a Yoderbilt Greenhouse.

There are several different methods you can use. I decided to use the container method because it made the most sense for me. I gathered my supplies: loads of 6-inch terra cotta pots (my preference), potting soil made for containers, and garden shears. 

To be honest, this first step of preparation is by far the most time-consuming. I picked a nice warm day and collected the geraniums from my patio, porches, and garden. Some I transported in their containers, and others I dug up.

I gathered and inspected the geraniums and decided on which ones to keep. If they looked the least bit diseased, I discarded them. Then, I spent time removing them from their containers. I gently removed the dirt from their roots and any damaged leaves, extra stems, leaves, or blooms. Next, any part of the stem that was going under the soil was thoroughly cleaned from leaves and buds. This would aid in not allowing any rot to occur. When you have well over a hundred, this takes a bit of time. 

Several blooming geranium flowers in multiple pots inside a Yoderbilt Greenhouse.

Although I used the container method, I did different variations within that method. I planted two large urns that were to provide continual starts throughout winter. Those were my primary mother plants. 

Then, I planted a huge number of single plants that I had separated into 6-inch terra cotta pots. I wanted to test their growth in comparison to the same size pot having 2-3 plants. Remember, I removed all extra foliage and blooms (for the most part). This allowed the energy to focus on the root system.

I found a few "baby" geranium plants within the mother plants. For those, I started in smaller 3-inch pots and potted those into larger ones as winter progressed. It didn't take long before they grew like crazy. I had some 2-3 inch branches that broke. I cleaned them well by removing leaves, blooms, etc., and planted them into the soil. I did not use any rooting hormone.

I kept some larger pots that were on my patio. I inspected well and removed the debris, and reconditioned the soil. I made sure I didn't carry in any pests inside the greenhouse. I also made sure all containers had about an inch of space at the top to allow for watering. I then watered them - thoroughly soaking them and allowing the water to run through. 

The watering process throughout winter was vital. First, I watered to the top of the pot rims. Then, I allowed them to dry out completely. And repeated over and over again all winter long. 

The greenhouse made overwintering easy. The light provided was perfect. I checked them often and watered as needed. I removed any dead foliage. I kept the temperature above 45 degrees. I kept air circulating by way of a fan(s). My greenhouse also has an auto vent, double doors, and windows. Those were open on the days the greenhouse heated up from the sun. I made sure good ventilation was in place. Geraniums can develop mold, and that never became an issue.

Unpotted plant laying on a wooden table.

My initial plan was to keep them in a somewhat dormant state. I didn't expect big gorgeous foliage or deep green foliage. Well, these geraniums had different plans. They flourished.

In a few weeks, they were growing and blooming to the point I had to take a second harvest of new cuttings for starts. This was one month later. So, I had to buy many more terra cotta pots. It was a great problem to have. 

On a cool morning within the first month, I walked into the greenhouse, coffee in hand, and was greeted by spring in the middle of winter. Pops of color: pink, reds, and salmon. It was then I decided to let them bloom. 

And, bloom, they did. They have given me such joy this first overwintering season. I did begin a diluted half-strength fertilizer of Miracle Grow about once every 4-6 weeks. If I had tried to keep them in a more dormant state, I wouldn't have done that. 

In overwintering, my ultimate goal was to get new starts for propagation in late winter for early spring. But, they gave me so much more. Was it worth it? 

100% yes! 

This was my personal experience that I wanted to share, and I hope you enjoy your gardening journey as much I do! This post was to explain my overwintering process. I'll make a post soon on starting new plants from cuttings. It's been a game-changer too.