It can be tempting to try to hurry your seedlings along by planting them directly into the garden once the soil has warmed and the danger of frost has diminished. However, it’s important that you give your plants plenty of time to adjust from the indoor temperatures to the conditions provided outdoors.
Transitioning your plants requires a period of adaptation called “hardening off.” This gradually exposes your delicate plants to natural elements that simply aren’t found indoors, such as wind, direct sunlight, and driving rain. A good transitional period allows your plants to develop a thick cuticle on their leaves so that they lose less water and remain stronger when exposed to the harsh natural elements.
- Know your stats
The length of time a seedling requires to harden off depends on the type of plants you are growing and the temperature and temperature fluctuations. So be flexible when hardening off your seedlings and be prepared to whisk them indoors or cover them if there is a late freeze or snow.
- Start off small
Don’t try to do it all at once. Make sure you gradually expose your plants to longer periods of time outside, instead of leaving them out in the harsh elements all day. Start by placing them outdoors about a week before the desired transplant date. Leave them outside for about three hours at first, and then increase the time by about an hour each day. Bring them back inside to a heated garage or other moderate-temperature area each night. If temperatures have risen to above fifty degrees both day and night, you’re probably safe to leave the plants out both day and night after a full seven days of transitioning.
- Use a cold frame
Cold frames allow you to transition plants in cooler-weather areas. To transition in a cold frame, you should again begin moving them out about a week before your desired transplant date. A cold frame provides a warmer, more sheltered environment, but you will need to water regularly while they are in there, as they can’t receive as much direct moisture. However, using a cold frame eliminates needing to move them back inside. Just turn of the heating cables or open the cold frame cover for longer periods of time each day, building up to a full day of exposure by the end of the week.
- Transplant on a cloudy day
Try to transplant when the weather is overcast and there is rain in the forecast–but it’s not currently raining. Make sure there are no heat waves, frosts, or other radical temperature changes on the horizon. If you can’t make your planting schedule cooperate with your other commitments–because we know you probably have more going on in your life than simply planting your garden–try to plant in the late afternoon or early evening. This will reduce the amount of time the plants have to spend languishing in the sun and reduce moisture loss. Water the day before transplanting so that the soil is still moist and you don’t have to work to get the seedlings out of the starter trays.
- Consider withholding water
This tip is more controversial, but some gardeners adamantly believe that withholding water for a few days can have the same effect as periodically exposing the plants to the elements. By allowing the seedlings to wilt, you will mimic the hardships they will face outside and prepare them for the necessary trauma of transplanting. Start withholding water about two weeks before the transplant date and watch them for signs of wilting. Once they begin to wilt, you can water them again. Repeat this process for two weeks.
- Be careful where you put your fingers
When you are ready to transplant, make sure you pick up the seedling by its leaves–not its stem. The stem transports all of the plant’s vital nutrients, and applying too much pressure there can kill the plant.
- Keep your seedlings in the dark
Make sure your seedlings are resting in the shade until you’re ready to plant them–don’t leave trays lying out in direct sunlight while you work. Likewise, don’t remove a plant from its container until you’ve already dug its hole and prepped the area. The goal is to have it out in the direct air for as little time as possible.
- Don’t force it
If you’re having trouble getting the seedling out of the tray, don’t tug on it. Instead, hold the container in one hand and flip it upside down. Tap it on the bottom, but lightly (with a little less force than if you were trying to get the last bit of shampoo out of a bottle, for example). The root ball should pop out into your other hand. Make sure you prune away any damaged roots and tease the healthy roots away from the center to prevent them from becoming bound as they grow.
- Plant deep–but not too deep
You should plant your seedlings at the approximate depths of their original containers, if not a little bit deeper. Depth is incredibly important at this stage because if you plant too deeply, this can cause rotting in wet or cold soils. However, plants like tomatoes must be planted deep. Those planted up to their first set of leaves set fruit earlier and in greater quantities. Make sure the soil around your seedling is firm, but not too compacted.
- Consider adding PlantCatalyst®
PlantCatalyst® is a phenomenal plant additive that can help make the transition from sill-to-garden easier on your plants. This organic, non-toxic compound helps plants absorb nutrients more naturally, increasing your garden’s fertility and overall productivity.
PlantCatalyst® has been used by homeowners for nearly forty years, and can help ease the springtime transition for your plants. It can be added to the soil long before planting, or to the planting hole before you insert your transplants. Consider adding it this spring to make the process of hardening off your plants more lucrative.
No doubt, you’ll likely feel the strong urge to begin planting your garden on the first warm, sunny day that comes around this spring. However, resist the temptation and make sure you have hardened off your plants first. Your garden will thank you.