How To Harden Off Vegetable And Flower Transplants – And Why It’s Important!

So just exactly how do you harden off vegetable and flower plants before planting in the spring? And why is it so important to their success?

Whether you grow vegetable and flower plants from seed, or purchase flats from a nursery, it’s vital to prepare young plants for life outdoors before planting them directly into the ground.

hardening off vegetable plants
Plants need time to adjust to the rigors of outdoor life before transplanting.

And this process of preparation is known as hardening off plants. Unfortunately, it’s one of the most overlooked spring gardening chores of all.

And yet, so important to your overall planting success!

The Importance Of Hardening Off Vegetable And Flower Transplants

Up until the time transplants go in the ground, they are living easy. By growing indoors, they have complete shelter from the dangers of growing outdoors.

There are no heavy winds and pounding rains. Nor are there huge swings in temperatures. The plants also don’t have to deal with scorching afternoon sun, or frosty overnights.

And watering? Well it comes regularly as well.

seedlings indoors
Plants grown indoors have little worry about. But out in nature, that all changes quickly.

But all of those cozy conditions change drastically on transplanting day. And if plants are not ready for the harsh conditions, they can suffer serious damage quickly.

Damage that can stunt a plant, and seriously impact its permanent growth and vitality. Unfortunately, in some cases, it even results in a tender plants total demise.

How To Harden Off Vegetable And Flower Plants

Young plants need time to adjust to the sunlight, wind and temperature swings of the great outdoors. And that adjustment time depends on whether you have raised your own seedlings, or purchased them from a greenhouse.

On average, home-raised plants need two to three weeks of hardening off, while nursery plants usually need a few days to a week at most.

pumpkin seedlings
Home raised seedlings need a few weeks of hardening off to adjust to outdoor conditions before planting.

Why the difference? Plants raised from seed at home tend to be less developed than those purchased in stores.

The main reason is commercial growers start their seeds extremely early. Because of this, plants have had longer to grow and mature. In addition, commercial greenhouses have controlled lighting, watering and fertilizing, all of which lead to bigger, more developed plants.

Hardening Off Home Raised Transplants

For home-grown transplants, begin by setting plants out during warm afternoons two to three weeks before your anticipated planting day. Be sure to do this in a protected area.

Porches are perfect, as are areas near the house. This initial protection helps them get acclimated to the outdoor elements slowly. As each day progresses, allow them more sun and more exposure.

harden off vegetable and flower plants
Seedling grown in commercial greenhouses are usually started earlier than most seeds at home.

Continue to let transplants get more time outside each day as the weather allows. With a week or so to go before planting day, only move them indoors if the temperatures approach frost, or brisk winds or heavy rains are forecast.

A few days before the planting day, leave plants outside in the full sun and light. At this point, they are hardened off and ready for planting!

Store Bought Transplants

For store-bought plants, the process is a bit less intense. It really comes down to the size and age of the vegetable or flower plants.

harden off vegetable and flower plants
The tomato plants have adjusted to outdoor life, and are ready for planting!

Many large flat of plants at nurseries have already spent a bit of time outdoors on racks or shelves. For these more mature plants, hardening off is really not necessary.

But if plants are on the smaller side, or have been inside exclusively at the nursery, you will definitely want to harden them off for at least a week to prepare them for outdoor life.

Here is to hardening off your flower and vegetable seedlings, and to getting the most from your plants this year! For more great advice on vegetable gardening, check out our Growing Vegetables tab on the site.

This Is My Garden is a garden website created by gardeners, publishing two articles every week, 52 weeks a year. This article may contain affiliate links.

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