Spring is here and summer is near! You’ve prepared your garden space and have been thinking about what plants you want to grow this year. Maybe you started your plants from seed and have them growing in your home or greenhouse. Or maybe you’re relying on your local greenhouse to purchase your starts from. Regardless, there are some tips you should probably know so that you can set your starts up for success in your garden. There is nothing worse than spending the time and money preparing your garden and planting your starts only to end up with dead starts in less than a week or so. Instead, if you truly work to start your plants right you can end up with an over bountiful garden, truly a good problem to have!
Considerations when bringing the starts home from the greenhouse
If you choose to purchase your plants from a greenhouse, transitioning them to outdoor conditions usually goes much smoother. Since they we’re exposed to natural sunlight, albeit through plastic, they will naturally have more resistance to sun scald. Sun scald is when the sun burns a plant’s leaves, turning them white and sometimes brittle. The plants were also already exposed to fluctuating temperatures from day to night. However, there are still a few precautions to take. The key thing to remember is that you don’t want to shock the plant.
While they have more resistance than plants grown indoors, I still don’t recommend placing them in an overly sunny space right away when you bring them home. Instead, place them in a partial shade location. This will allow the starts to transition from filtered natural light to full sun without resulting in scalded plants. I usually let mine sit in this location for a couple days before planting. Some greenhouses do harden off their plants, build their resistance to the sun and elements, but not all.
Also, keep them well watered. At a green house, they monitor the plants closely. However, you might have purchased the starts right before they would have otherwise been watered. If the soil is drenched, you might wait to water the starts. However, in most cases, I recommend drenching the starts when you get them home. Make sure they are located in a place where any excess water can drain away.
Lastly, watch your night temperature drops. In a greenhouse or high tunnel, plant starts are more protected from chilly nights since the air maintains a higher temperature inside. If you simply place your plants outdoors and the temperature dips down fairly low, you might have damaged plants. You may want to put them in a garage or another location overnight if you are worried about a frost.
Steps to hardening off your home plant starts from seed
Hardening off your home-grown plant starts so that they are resilient to outdoor conditions takes a good bit of time. It’s upwards of at least a week of dragging your plant starts in and out of your house or home greenhouse. However, if you don’t take the steps to harden off your starts, all of your work up until that point will have likely been wasted when they die.
Something that you can do as your plants grow is expose them to artificial wind to strengthen their stems. By strengthening their stems, they will be stronger and more resilient to wind when you plant them outside. I choose to use a gentle fan on the starts as they grow from seedlings. Oscillating fans are best as it isn’t a constant breeze, however you can use a box fan if necessary and just keep the breeze low and move it frequently. The key is to slowly strengthen them, not snap the stems!
Slow UV Transition
When you go to harden them off to direct UV rays, you want to tread carefully. Sun scald can be deadly if the starts don’t have any prior direct exposure. If you placed your starts outdoors in direct sun right away, you likely won’t have any plant leaves left. Yes, even on a cloudy day! Slowly work up to direct sun by starting with just an hour or two in the evening or in a shady area. From there, each day increase the amount of time by about an hour. Watch your weather as well. If it’s an excessively windy day, placing your plants outside might leave them in tatters.
A final things to consider when hardening off your home-grown plant starts is that while you leave them outside longer and longer and if it’s breezy out, your plants will need more water than usual. Make sure to just monitor the soil. Take this into consideration as you prepare to undergo the process.
A sample hardening off period might look something like this.
- Day 1: Place outside in later evening hours for period of 1-2 hours.
- Day 2: Repeat.
- Day 3: Place outside in evening hours for 3-4 hours.
- Day 4: Repeat.
- Day 5: Place outside in evening hours for 4-6 hours. If nighttime temperature is to remain above 40˚F, you may consider leaving the plants out overnight and into the morning for a couple of hours.
- Day 6: Repeat.
- Day 7: Repeat and extend into the next day further. You may consider placing them in a location that is shaded over noon (time with strongest UV rays).
- Day 8: Repeat.
Getting your plants in the ground
Just like shocking your plants during the hardening off phase can be bad, so can shock when you go to plant them in the ground. Some basic precautions taken at transplant time can mean happy and healthy plants that undergo a smooth transition.
Ten Day Forecast
First, don’t go plant your starts until you are close to your area’s last frost date and your 10-day forecast has good temperatures, mainly lows above 40˚F. The 10-day forecast doesn’t always mean that your plants won’t encounter a frost, but it’s definitely a good guide.
I highly suggest offering your young starts some protection from the wind, especially if you live in a mid-western prairie state. The wind can be brutal there! There are so many options to consider, but the main thing is to provide some protection for the individual plant for the first bit as they transition to the constant outdoors. Personally, I use old planter press wheel tires. They are essentially just a small tire that you can stack to provide adequate protection for a plant. Other good examples are coffee cans with the bottoms cut out, milk jugs with the tops and bottom cut off, bottomless 5-gallon buckets (possibly cut in half). Be creative! Find what you have easily available. The key is to make sure to press the object into the soil to keep it anchored in place. Once the plant is more established and stronger, you can remove these.
My final tip for transplanting time is to water right away. Remember that the key is to not shock the plant. You want the new environment to be hospitable. When you go to plant, I recommend digging your hole and then adding at least two cups of water and your transplant. Fill in the hole around the transplant and then water again. This will help keep those roots fully saturated and loosen the soil around it to allow them to easily grow. Providing a good new environment for those roots is so important! Transplanting into dry soil tends to result in starts that go through a little bit of stress and shock and are therefore set back some. They might still survive, but maybe not thrive.
Getting your starts into the ground can entail more detail than simply planting the start. But the main goal of every step along the way is to slowly transition the starts to allow them to adjust. By avoiding shock, your starts can keep progressing into beautiful productive plants in your garden. I wish you all the best with your garden. A green thumb isn’t always a natural gift, but it can definitely be learned!