For twenty-odd springs, the months of April and May would see me working away on the last minute seeding, plant care and helping out with the transplanting in the propagation greenhouse.
And while I don’t miss the rush of spring in the nursery business, I do miss the greenhouse with its earthy, humid smells and warm shirt-off temperatures.
Seedlings and cuttings demand extra attention before they go into the garden.
I don’t plant seedlings or cuttings directly into the garden. In my garden world, every one gets their own individual three or four-inch peat pot filled with the best soilless mix I can find.
With one plant to a pot, there ís no competition for nutrients or space and no transplant shock when the plant goes out to the garden.
Plastic pots are fine for plant-growth.
Soils For Growing On
After all those years in the greenhouse, I know that tender seedlings do much better in pure soilless mix than they do in any super-soil you can purchase or make.
Compost adds a dimension of plant nutrition but it also changes the soil drainage drastically. I don’t use it.
Real soil from the garden has no place in my seedling pots. It goes rock hard under constant watering and unless you sterilize it – there’s a serious possibility of problems.
Getting Watering Right
I wet each pot thoroughly before I transplant the seedlings because I want to ensure the tender roots will not contact dry soil and die.
Water the seedling pot well at least an hour before you begin transplanting so that each seedling will be gorged with water.
You’re about to wreck their root system and if they are suffering from water shortage before you transplant them, the survival rate will be low.
Transplanting The Young Seedling
Moving young plants is easy. After 20 years and over a million seedlings, I don’t have any trouble at all.
If you do, let me give you the trick that will make all the difference.
- Handle each seedling by the leaves.
- Do not pick them up by the stem.
You can ruin a leaf or five and the plant will grow more.
If you squeeze the stem and bruise it, the plant will often grow weakly for a few weeks and then die. The bruised area won’t support top growth.
I usually knock the entire soil ball out of the pot and separate seedlings from the mass of roots. I try to get soil with each seedling but if it comes away clean it is no big deal.
I simply move it over to the empty pot and bury all the roots.
After the roots are buried in the new soil, I water that new transplant again to ensure the soil is damp and all tender roots are well covered and in contact with damp soil.
Light levels For Great Growth
The transplanted pots are put in the shade or anywhere where there isn’t direct hot sunlight for a few days and then moved into as full sunlight as I have. The shady time allows the seedling to recover from the root damage without having to deal with full hot sunshine and the subsequent water loss from its leaves.
Once the seedling is standing back upright again, it can easily handle all the sunshine you can give it.
The unpleasant truth is that unless you have a full south window, the light levels are not going to be high enough to grow a good plant. If you see stretching of the seedling or cutting, you know that low light is the primary problem.
This means to produce good plants you need grow lights.
Install them on a moveable chain system so they can be raised or lowered. You want to keep these lights about 4 inches above the leaf canopy to get the right amount of light onto your plants. As your plants grow, raise the lights to maintain this distance.
Feeding Tender Transplants
I feed my seedlings with a half strength water-soluble plant food. They get this weekly for the first month.
When the seedlings are producing new “true” leaves, I move the plant food to the full strength formula for their weekly feeding until they go outside. (True leaves are the leaves that resemble the mature plant. These follow the 2-4 seedling leaves that are the first ones produced by the plant)
Going outside requires a few days of hardening off. This means the plants are put outdoors for an hour the first day, two hours the second, four the third and increased gradually until they are outdoors from daylight to dusk.
Before leaving them outdoors as night get the plants hardened off during the day first.
Then, as long as the nights are warm, the seedlings can be left outdoors after the first week and a half of in-out hardening off.
If the temperature is cold, (day or night) do not leave the annual seedlings outdoors; they will not appreciate temperatures less than 50F. during this hardening off process.
This is a good example of “cold damage” on a tomato transplant. It will grow out of it but it sets the plant growth rate back.
However, once the seedlings are hardened off, they can be planted in the garden once all danger of frost has passed and they won’t suffer transplant shock.
You can read other plant propagation articles right here.