Starting seeds in an unheated garden greenhouse is a simple and effective method for nurturing seedlings until they are ready for outdoor transplanting. The process involves placing seedlings in their seed starting trays or pots, and ensuring they are protected from overheating, drying out, and pests. To ensure successful transplanting, it is essential to remove any weeds, rocks, or debris from the planting area, as competition for nutrients and space can hinder seedling growth.
Timing is crucial when transplanting seedlings, as they should have at least two sets of leaves upwards, usually when they are 2-4 weeks old. A greenhouse allows you to sow seeds at almost any time of year, depending on the winter temperatures in your climate zone. The spring planting season, at least until late April, is the time to add, split, or transplant Hardy plants to your garden. By April, it is usually safe to place flats of warmth-loving plants in the greenhouse.
In a controlled environment, you can start seeds in greenhouses anytime, but there is no point in starting plants indoors before early March. Many growers wait until late March or early April to start seeds indoors. In the greenhouse, start canna and dahlia bulbs in larger pots and “harden off” any indoor pots you bring back outside. Gardeners like Ryan and Wilmer plant seeds into flats every week from now through March, when the weather is warm enough to garden outdoors.
In summary, starting seeds in a greenhouse provides a stable atmosphere for germinating seeds and nurturing them until they are ready for outdoor transplanting. Proper timing and care are crucial for successful seedling growth and successful gardening.
📹 How to Tell When It’s Time To Transplant Seedlings
Seedlings grow fast, but as they grow, how do you know when it is the right time to transplant them or up-pot then to larger …
Can a greenhouse be too hot for seedlings?
To ensure optimal greenhouse ventilation, use a maximum-minimum thermometer to monitor the temperature and be alert for signs of plant damage. Open doors and vents on sunny days, and temporarily remove panes to help during heat waves. Fit automatic vent openers to ensure roof vents open even when you’re not around, but remember that it takes time for the wax to expand. Provide alternative ventilation such as doors and side vents to prevent damaging temperatures. In changeable weather, vents and doors may need to be partially open to limit sudden temperature increases. Larger greenhouses may require automated ventilation and shading.
Shading is usually required from mid-spring until early autumn to release some heat but limits the light plants receive. Use only the minimum amount of shading to keep temperatures below 25-27ºC (77-81ºF), allowing as much light in as possible, especially for edible plants like tomatoes. Sun-loving plants like succulents may not need shading, but providing shade can make the greenhouse more pleasant.
Do I need to harden off seedlings before putting in greenhouse?
Hardening off is a crucial process for mature plants grown inside a greenhouse, as it involves slowly acclimating them to a new environment to prevent shock, damage, or even death. When plants are raised indoors in early spring and moved outside for planting, they must adapt to direct sun, cooler temperatures, lower humidity, increased air movement, winds, and pest and disease pressures, which are unpredictable and out of control.
Proper hardening off results in thicker cell walls and leaf structures, increased energy for root development, and reduced excess water, making the plant stronger, more rigid, and less susceptible to freeze damage. As plants grow slower, they create a firmer, less floppy plant that can handle the stresses of the outdoors. If not hardened off, wind, sun, or cold can lead to significant wilting, browning leaf edges, or even death.
Hardening off is a time-intensive process, ideally done over two weeks, but it is generally more sensitive than bringing home well-rooted, mature plants from a greenhouse and acclimating them to their new environment. It is essential to follow guidelines for hardening plants off when preparing for outdoor planting and to simplify the process when moving crops outside for sale or at home.
Do seedlings get leggy in a greenhouse?
At temperatures between 70 and 75 degrees Celsius, seedlings begin to exhibit signs of stress, such as stunted growth and a lack of vigor. In such instances, it is advisable to either unplug the device or transfer the seedlings to a cooler environment, particularly if a heat mat is in use.
When can I put my tomato seedlings in the greenhouse?
Transplanting tomato seedlings into an unheated greenhouse is crucial once frost has passed and night-time temperatures remain above 10°C. Harden off seedlings gradually by exposing them to outdoor conditions for increasing durations each day. To protect against cold, consider using row covers, fleece, or horticultural bubble wrap for insulation during chilly nights. Watering plants during the day can also moderate temperature fluctuations.
Regularly monitor plant growth and environmental conditions, including temperature fluctuations, moisture levels, and pest activity. Prune plants as needed to promote airflow and prevent overcrowding, which can contribute to disease development.
What is the lowest temperature for tomato seedlings?
Tomato plants cannot survive below 35 degrees Fahrenheit and 50 degrees Fahrenheit. To ensure plant survival, use a frost date calendar to track average dates of last frost in spring and first frost in fall. Tomatoes thrive between 55 and 85 degrees Fahrenheit. Check plant tags for variety information, but tomatoes typically won’t set fruit when temperatures hit 85 degrees and may struggle to set color in the heat. Starting tomatoes early allows them to set fruit before the hottest summer days.
When can you move seedlings to an unheated greenhouse?
The author begins moving hardiest seedlings into their unheated greenhouse once temperatures drop below a few degrees above zero. The first wave of plants include leeks, onions, pansies, violas, cabbage family vegetables, sweet peas, snapdragons, endive, escarole, and lettuce. Tom Thumb lettuce, an heirloom from 1830, is placed first, known for its easy-growing, hardy nature. The Little Gem type miniature romaines also perform well in cold weather. By April, flats of warmth-loving plants should be placed in the greenhouse.
Why are my seedlings dying in my greenhouse?
Damping off disease is a disease that affects seeds before they germinate, where a pathogen that thrives on too-wet conditions can grow and kill the seeds before they can emerge. Common reasons for seedling failure include poor soil conditions, such as too little or too much water, and inadequate light. Some of the most common mistakes made in gardening include not having enough water, not having enough light, and not having enough light.
To prevent seeds from failing to germinate, it is essential to maintain a suitable soil temperature of 65°-75°F, which is generally recommended for most seeds. This temperature should be maintained at a level that is neither too hot nor too cold, and that the light should be evenly distributed throughout the plant. By addressing these common mistakes, gardening can help identify what is working and improve the overall success of your plants.
When should I move my plants into the greenhouse?
To start tomatoes, wait for the right conditions and start them in mid to late March if planting is not until May. Avoid covering plants and keep them close to light or high on a greenhouse shelf. Keep the temperature as cool as possible without dipping below plus 5 C. Place a fan near plants to expose them to stress. If necessary, bury tall plants deeper when transplanting. If stuck, grab one of the sturdy tomatoes, which have been stressed and kept short on purpose, and they will thrive in warm, moist greenhouse soil.
Can you put seeds straight into greenhouse?
A greenhouse is a controlled environment that helps control the temperature and humidity needed for seeds and seedlings to grow. To start plants in the spring, start seeds in the greenhouse six to eight weeks before the expected frost date. Ensure that seeds germinate in a temperature between 70-80 F. (21-27 C.) and monitor the greenhouse’s temperature closely. A seedling heat mat can help maintain consistent soil temperatures, and if the greenhouse gets very hot, open windows or install fans to maintain suitable temperatures.
Seeds can be started inside individual plug trays or open flat seed trays, depending on their requirements. Some seeds require scarification, stratification, or overnight soaking before planting. For open flat trays, consider spacing seeds in carefully spaced rows for easier thinning, fertilizing, and watering processes, as well as for treating seedling diseases.
When should I transplant my tomato seedlings?
In order to facilitate the transplantation of tomato seedlings, it is recommended that the process be initiated in mid-March. This can be achieved by placing the seedlings on a heating pad beneath a plastic covering. A period of two to three weeks is required for germination and the emergence of the first set of true leaves. Following a period of three weeks, the seedlings are prepared for transfer to a larger container with soft soil and bright white roots. The seedlings have reached the optimal stage for transplantation.
How long should seedlings stay in a propagator?
To prepare seedlings for planting, remove the seed tray cover and let them grow for a few days to a week. Start by removing the cover during the day and replacing it at night until the seedlings are strong enough to leave it off. Once the process is complete, transplant the seedlings into pots with more space for their roots and development. Economy pots are typically used for this process. Once the seedlings are ready to plant, they should be ready to move into their permanent location.
📹 How to Transplant Seedlings and Direct Sow Seeds in your Greenhouse
Follow along with Heather as she walks you through the dos and don’ts of transplanting and direct seeding in your Growing Dome …
I’ve found that one way to fix floppy lettuce seedlings is to put a ring around them such as a toilet paper tube (the earlier the better as soon as you see floppiness). I’ve had a few I thought were goners whose leaves were even starting to get plastered to the soil that I saved this way and once their stems got thicker they stood up much better. I have gotten a good harvest from all of them and none went to waste. Also if you transplant them in a mason jar with a small bubbler in the bottom you can bury them a little deeper in clay pebbles inside a net cup without getting crown rot. Several of mine got really strong that way; even better than the toilet paper roll method!
I was totally doing that “I’m gonna fix this plant and make it straighter by replanting it deeper.” Did that to ALL my leggy seedlings before I found out I needed to buy a grow light lol. perusal this website can save a lot of headaches!! Great content keep it up, one of my new favourite websites to watch!!👍👍😎
Very useful and informative. Thanks! Funnily enough I was just going through my daughter’s science schoolwork with her a few hours ago before I watched this. Her chapter was about where molecules for plant growth come from. I assumed at least a large portion of the plant’s mass from growth came from the soil, but an old experiment by Van Helmont actually showed that the mass of soil a plant grows in changes very little. It was later discovered that the new plant mass comes mostly from the air and water. The soil in your pots is likely about the same mass as it was when you first planted your house plants. It’s just broken down a bit, so it takes up less space than it used to, to make room for all those roots. Very little of it was consumed by your plants.
Thanks for this and all of the articles you make. I’m about to plant my first seeds EVER, TODAY. I’m in SW Michigan, so indoors, of course. I was so happy to see this instructional article, to help keep me from making mistakes when it’s time to transplant the seedlings. Last frost date here is May 1st, so I have 7 weeks until then, AND, will still need to keep an eye on the weather before transplanting outdoors for the non-frost hardy varieties – as we all know that last frost date is the average and it’s going to vary year to year. 3/12 and it’s snowing, lightly. Here we go!
So many questions answere here today. Thank you, Luke! Soaking-up everything you say in this series, because I’ve got an entire garden’s worth of your seeds I don’t want to screw-up this season. This year, we’re going to try to live off what we produce here on our little farm, and I’m a 100% gardening noob. Learning all I can from you before I start making mistakes. Thank you for all you’re doing, we really appreciate you.
Awesome – I just transplanted a few tomato sprouts into bigger pots because this is what I did – I made like 4 little holes in a 6×6 and just threw in like 4-6 seeds in each hole – so I gotta transplant them asap before they grow bigger and the roots get tangled! They are roughly 1-2 weeks old, tiny little things 🌱 And that strategy kinda backfired – I now have more sprouts than available pots, Walmart doesn’t have those trays, only individual pots
I had just watched Gardiner Scott talking about seed packaging & he mentioned MIGardiner in that review 🙂 I felt I should get some seeds from you just for that reason, Mostly Walmart, Home Depot, or Green Acres… they are local. In a mobile home park, there is not much space to garden, but everybody has their own cross to bear. I don’t have a green house, & trying to grow in side is an issue as my cats like to eat what germinates. So, I am late with tomatoes & peppers already, what can I plant outside in Sacramento, CA… BTW, I love your articles, lost of 🙂 Thank You, & your team… after all, Team Work, makes the Whole thing work!
I was surprised to see your Aloe Vera. I and my Mom have been growing them for over 60 years. When she moved out of the house I took a plant with me to care for it. I have repotted several times, and in 2019, a 3 1/2 foot spike grew and bloomed. I had never seen anything like that in my life. The blossoms were green and not real pretty, but another growing miracle occurred. The original plant was found near a garbage drop, and when rolling the dice and planting grew like a champion. My Aloe Vera has 50 plus shoots growing in the pot with it, another surprise, and time to repot them and the parent now. With my seed starting system I transplant them from the small starting tray to 3 inch pots when they get the first main leaves on the stem. I grow tomatoes, peppers, basil and flowers this way and it seems to work well and I don’t have to deal with any empty pots due to nonsprouting. I like this article Luke. Thanks.
Thank you for all the articles! I started gardening last year but most of my plants did not make it sadly. Wish I would have found your website sooner. I had a watermelon plant last year but an animal ate into it, is there anything I can do to prevent animals from eating my plants but still make sure they can get the sunlight and water they need?
Hi Luke and/or fellow gardeners…thoughts on whether you should let fruits set before transplanting? Have seen lots of articles from others on not buying plants that already have fruits, but what if you need a longer season to get certain veges and fruits ripe before end of season. Trying to decide how early to start melons and long growing vege indoors before transplanting but need some advice…thx a bunch! (I tried to find a article you may have already done on this but was unsuccessful)
Hey Luke, what do we do when we can’t transplant yet? SoCal is having the coldest spring in decades, so we can’t put them in the earth yet, but my seed-starting pods are getting huge already. I began transplanting into 3.5″ plastic pots with the largest ones, is this a good plan for the meantime? Nice to see you brother.
I have a question. I;m planing my MI Gardener onion seeds I got from you earlier in the year. The onions are in a 1×1 right now and are about 2 inches in height. They are all flopped over right now. Will the straighten up and they continue to grow? I’ll also be starting my MI Gardener tomatoes. Is end of Feb a good time to start them?
Before planting an established plant I usually water the soil in the hole and then leave it for five minutes so that the roots go into to fully moist soil. Also if the roots are gathered together in the bottom of the starting pot l usually tease them out sideways and spread them out in the soil as I plant