I never thought I would write an article on acclimatization. Since I have been in the horticultural world, I have been familiar with this concept. I explain it extensively during conferences, there is even a whole video that addresses this concept in the online training of Urbainculteurs. The principle is quite simple: get our little seedlings used to the realities of the outside world before transplanting them permanently to the vegetable garden. Well, I have to tell you a secret: I’ve never been very good at actually applying this principle in my gardening routine. I told myself that it must be superfluous, that plants are able to adapt quickly, that it is not really necessary. What naivety!

As mentioned in previous posts, I am in charge of planning and managing the production at the Urbainculteurs’ urban farm, Les Jardins du bassin Louise. Despite our limited office space, I can produce the majority of the transplants that will be grown on the farm. We have built four shelves that can accommodate twelve trays each. I focus on plants that do not need transplanting in bigger pots to maximize the space allocated to me. As for plants of the nightshade family, I buy organic transplants that are produced by the Naturo greenhouses in Bellechasse.

Small transplants in “ideal” conditions
Credit : Les Urbainculteurs

How Can the Cobbler Not to Be the Worst-Shod

In my first year of production, I told myself that it would be really important that I integrate the acclimatization process into the steps of my routine. I want a quality production, so I might as well put the odds on my side! As I plan my season in advance, I already know which crops will be produced and when. It is easy for me to put on the agenda the moment of acclimatization a week before planting on the farm.

Moving From Theory to Practice

But hey, the implementation of this magnificent planning is not always so easy to achieve when we are in the thick of it, at the start of the season. Sometimes I’m in the office, sometimes I’m just on the farm. Sometimes I pass in a hurry and leave quickly to help on other projects, sometimes I am simply absent. And that’s just me, but everyone at Urbainculteurs is snowed under with work in May and June. My colleagues are of great help, but in all this hubbub, rigor can sometimes be lacking. You see me coming, don’t you? Acclimatization sometimes takes a hit.

I must admit that I was very lucky overall, but a small incident last year reminded me of the importance of this so-called acclimatization. In summary, I did not acclimatize my celery enough and they never recovered. Sunburn on the stems, slow recovery, stagnant growth, lousy appearance. I don’t have any supporting photos, I’m already ashamed enough as it is!

Getting ready for a day out
Credit : Les Urbainculteurs

Don’t Make the Same Mistake as Me

In order to remind myself that I don’t want this to happen again and to convince you to integrate this into your gardening routine, I am explaining to you the main steps for a smooth acclimatization.

When we start our seedlings at home, we create a little cocoon for our transplants. They are in womb for the beginning of their existence. Light, heat, water, space: we take the time to adjust each parameter to ensure exemplary growth. But outside, the reality is quite different. Rapid changes in temperature, rain, wind, pests, water stress, we move to a completely different living (or survival!) environment. Imagine the shock for these little plants. You don’t see it directly, but this type of stress can significantly compromise the success of your vegetable production. Here is what I suggest to you as a procedure.

Let’s go!
Credit : Les Urbainculteurs

A Simple Procedure

I start my acclimatization about a week before the planned planting date. Before taking the plants out, I make sure that everything is well watered. I have already found small plants all collapsed and dry in their cells. The wind and the sun have an impressive drying power.

Ideally, the outside temperature should be above 50? (10?) . If it’s lower, wait for a warmer day. Place your plants in a place that is not in direct sunlight and bring them in at midday. If you are outside the house and cannot bring the plants in at midday, make sure that the chosen location remains shaded all day long. Do this for 3 days.

Then choose a place with more direct sunlight and repeat this for a few more days. I never let my plants spend the night outside, I always bring them in at the end of the day (my working day). However, I consider that after a week, the plants are in theory well adapted, so can spend the night outside. If there is a risk of frost, don’t take a chance and bring them inside the house or cover them with a floating protective cover. Despite my celery “incident”, this method has proven itself for several years. Your plants are now ready to begin their new outdoor life!

Seedlings are ready to spend the day outside
Credit : Les Urbainculteurs

Watch Out for Frost

Depending on where you live, you should also pay attention to the risk of frost. Despite good acclimatization, some plants could be seriously affected or even die if subjected to prolonged frost. We are mainly talking about plants of the Solanaceae and Cucurbitaceae families, without forgetting basil. Be careful.

To End in Style

The last precautions are taken during the planting. Water your plants well before transplanting. Never pull on the stem to get the plant out of its pot. Instead, place the stem of the plant between your index and middle finger and turn the pot upside down. Apply light pressure to the pot and knock out the root ball. When transplanting, apply sufficient pressure to create contact between the root ball and the “real” soil. If you tug the seedling lightly after planting, it shouldn’t move or come out of the ground. Go ahead, the season is on!

A few lettuces
Credit : Les Urbainculteurs

Marie-Andrée is the urban farm manager and a trainer at Urbainculteurs, where she has been working since 2015. She plans and supervises the production of Jardins du bassin Louise, an urban vegetable farm with a social and educational vocation. Outstanding at teaching, she also co-hosts the podcast Mâche-patate and is one of the main trainers of the Urbainculteurs online training course. Les Urbainculteurs is a non-profit organization, based in Quebec since 2009. Their mission: to develop and promote a productive, accessible and responsible urban agriculture for the benefit of organizations and individuals, in order to increase food security, improve our living environments and promote an ecological transition.

2 comments on “Acclimatization

  1. Dan Bolton

    Gardening on purpose has always been a haphazard affair for me. Most of my attempts have centered around “survival of the fittest” which doesn’t work well if you want results. Last year I purposefully started a planned garden with the goal of harvesting food, and that’s where the hardening off/ acclimatizing philosophy shined, mostly.

    I learned that timing, frugality, and Mother Nature figure strongly into the gardening equation. In other words, I started my seedlings too early, I started too many seedlings, and unstable atmospheric conditions controlled what remained. My one true success last year was placing a fence between my homegrown treasure and the marauding deer.

    To increase my success this year I’ve controlled a few variables, that seem wise now, but only time will tell. Number one I’m growing what worked in my garden last year from seeds, or leftover seeds that I grew from last year, so no peppers, onions, cucumbers, or squash. These plants struggled to grow let alone produce in my climate. What did work were tomatoes, peas, beans, lettuce, arugula, radishes, beets, and carrots. Number two I’m keeping a journal of my garden with weather notes, planting notes, and general observations. I’m hoping to find some pattern, late in the game, but lemonaide from lemons. Number three is seed packages have too many seeds for my small 20’x20′ garden that uses only raised beds and containers. Not every seed is viable, or needs to be planted! Number four is the experimental part of trying a few new things that I didn’t have before. From our local nursery I chose two blueberry plants, a fig tree, and seed potatoes all to be trialed in containers. I watched a bumblebee working blueberry flowers yesterday, so my confidence is growing..

  2. Thanks for such a detailed and informative post.

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