How you can have a green thumb
Having a green thumb is a combination of good plant care habits and learning what really needs to be done. Seed starting requires slightly different knowledge and habits than taking care of stable seedlings or mature plants. If you want to have a green thumb for starting seeds, read on!
A lot of what is written below refers to seeds started indoors, but the same guidelines can be applied to seeds started out in the garden.
1. Choosing the right container
The size of the seed is a clue to the size of container you should consider. The size of the container will have some effect on how often you need to water the seeds before they sprout, particularly if they don’t sprout in the initial 3 days under the plastic canopy that I demonstrate in my video on Seed Starting Basics for the Home Gardener.
When it matters most is after the seed is sprouted. A large seed almost always means a large plant. If there is not enough soil there to support growth, including structural, the seedling will suffer.
Shape and drainage are also important. You want a container that is stable and one that will not form a pond. Shape will affect things like whether or not the container will stay put and whether or not you can dislodge the rootball for transplanting. It is always best to keep as much soil as possible with the roots when transplanting to minimize transplant shock.
Sometimes initial germination can be done in a flat tray filled with soil, with no boundaries between seeds. This takes up less space at first and can conserve on soil, since you only put the strongest sprouts in containers.
Soil blocks are another option. These can be formed by hand or with a soil block maker. I have used them a few times in the past. My main complaints about them are that 1) the soil blocks do tend to lose shape with each watering, no matter how gentle, and 2) the roots of the seedlings get tangled since they are not constrained by the sides of a pot.
2. Type of soil to start seeds in
Seeds will sprout easiest in looser soil, soil that stays predictably moist, soil that will still absorb water well once it gets dry, and soil that doesn’t form a crust. Not all seeds are equally affected by extremes of these conditions. The larger the seed or the more the seed likes warm weather, the more easily it will sprout in basic dirt. Smaller seeds, like carrots, sometimes can’t break through a crusty soil.
Knowing a seed’s preferences for soil type is a factor in whether to start them early in the greenhouse or direct plant them. The greenhouse can be a more controlled environment, leading to high germination rates. As long as you remember to harden off the seedlings before permanent planting outside, this works well.
However, greenhouse seedlings require more work in someways, since the environment has to be managed. This means it is not always the best use of time to plant seeds indoors. Reading the packages may help some. I have written 10 Criteria for Deciding Which Garden Seeds to Start Early in Your Greenhouse, but you may also have to experiment some based on your particular climate.
Most seeds have all the nutrients inside of them they need to sprout. A lot of potting soils have fertilizer in them that supposedly will last a couple of weeks. I start my seeds in one of those types of packaged soils. To be honest, I only irregularly add additional fertilizer my seedlings, and that usually only when they are out on the patio hardening off. I have never noticed that it makes a difference.
3. Plant seeds the correct depth
The pre-plant that is tucked inside a seed starts at a predetermined size. Upon sprouting, it needs to be able to reach the surface of the soil. This allows it to access light and air in order to be able to keep growing. If it is planted too deep, the poor little sprout will be buried the same day it sprouts. I use the rule of thumb of planting a seed to a depth twice the diameter of the seed.
If a large seed is planted too shallow, it will not have good support when it sprouts. The risk will be that the top of the seedling will over balance the roots, which might not have enough soil to grab. If the whole stem is above the soil, it may be inclined to bend in the wrong place.
4. Some seeds need light
Some smaller seeds, particularly flower seeds, may need light in order to germinate. Some seeds won’t germinate unless kept in the dark, even if only buried ⅛ of an inch. These things are usually mentioned clearly on the seed packet if they are important. If they are not mentioned, it probably doesn’t matter. Obviously, the deeper a seed is planted, the more dark it will be.
The New Seed Starters Handbook mentions that some seeds respond differently to light depending on the temperature. I searched the internet for more information on that and could not find more than the normal lists of which seeds need light to germinate, so that was disappointing. But, meanwhile, don’t forget that part of gardening is experimenting to discover what works best in your particular environment.
5. Temperature will affect germination
Soil temperature is important, even if it is dark. Most seeds have a temperature range in which they will germinate best. There also seems to be some hidden code in a given type of seed that keeps them from all sprouting at once. This is more pronounced in some seeds than others. This may be a fail safe in case conditions don’t end up being good for the first round of sprouts.
The Seed Starters Handbook has charts that may be useful for someone new to seed starting. Fortunately, many common garden seeds sprout in similar temperatures. And these temperatures seem to be related to the type of weather that the mature plants thrive in. This means that just keeping the greenhouse air in that range will be all you have to worry about for a certain group of plants. And since cool weather plants can also be hardened off sooner, the greenhouse can then be used for warmer weather sprouts.
6. Keeping seeds appropriately moist
Just how you go about keeping your sprouting seeds moist may depend on the overall humidity in your climate. Here in the high desert of Idaho, it really helps to keep most of my seeds under plastic for the first 3-5 days after planting. After that, fresh air is beneficial.
I start all seeds with the same basic procedure of high moisture (as I show in the my basic seed starting video, same as linked to above), but not all seeds like to be kept as moist after the initial moisture treatment. For instance, pepper seeds, squash seeds, bean seeds, and corn seeds like to be dryer than other seeds for sprouting.
The key is consistency. Whereas with growing plants it can be good to let them get a little dryer in between waterings, sprouting seeds need a very reliable environment. If you just think of poetic spring rains, you will have the correct idea. The seeds need to swell up and pop out of their compartment. Once that is done, they can begin to get what they need from the soil and light.
7. Know when to be patient
Seed dormancy can vary. Begin with reading the package your seeds come in, or looking up what is considered normal sprout times. This will help you be prepared to wait instead of assuming some seeds are dead.
If you really want to monitor what is going on with your seeds, consider planting enough seeds to incorporate some research into the process. Possibly have the same type of seeds set to sprout in a paper towel in baggy so that you can easily monitor progress. Make sure to keep them in the same temperature as those in the pots. This will not exactly duplicate the environment in the soil, but it will come close.
Another option is to plant more seeds than you plan on using. (An easy thing for most gardeners to do….) Dig up one pot of seeds a day. Plant more than one seed per pot. The smaller the seeds are, the less you will see until germination, since small seeds will blend with the soil. Once a seed is sprouted, there will usually be lighter colors to look for, but not necessarily much green, since they will need light to become truly green.
One more option would be to use clear plastic cups for some of your pots (Don’t forget about arranging drainage). Plant the seeds right next to the edge, where you can observe them more easily. This is not usually the recommended location for seedlings you hope to transplant because it means a lopsided root mass, as well as putting the stem more at risk during transplanting. However, learning what is going on with various seeds can make you have more success with your seed germination in the future.
8. Keeping the seedlings alive
Seedlings need light AS SOON AS THEY SPROUT! And head room to grow. If they are not already under lights during germination, they need to be moved under lights within a few hours after they show their heads above ground. Without light, all of your work will be at risk.
If the seedlings were under any kind of plastic, let them out. Most plastics tend to block light to some degree on their own. The condensation that also tends to accumulate also block the direct light needed for most plants.
Another reason to remove any covering after germination is that most lights also create heat. If you decide to keep using a dome or cover of some sort, be careful that you have taken this into consideration. And don’t forget that sunlight entering the greenhouse will add significantly to the heat.
Air flow is another reason for removing any covering. Most common garden plants will be suffer from the constant humidity under a cover. The leaves will not develop to conserver water. There will be more fungus type diseases. Insects will be attracted. One way or another, a constant cover tends to make the seedlings weak.
Keeping your thumb green
It doesn’t take a a rocket scientist to germinate seeds or care for seedlings. It takes a little knowhow coupled with dedication. This dedication doesn’t have to be time consuming, depending on how many seeds you plant, but it does have to involve regular, frequent monitoring.
Then, be ready for the next steps in seedling care. Try to have supplies and set-up ready. Know how you are going to give them light and water. Plan for when and where you will harden them off if they were started in the greenhouse.
Remember that everything gets easier with practice. The first time around it you will be developing both new habits and gaining new knowledge. Next time, it will be like playing a song you learned before. You will always learn things and get better at it, but the song will be easier to play and more enjoyable in the process!
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