This is the second in a twelve part series for new gardeners. If you have never planted vegetables before but always wanted to, this is the series for you. Robin, who writes the blog Vegetable Matter, and I will post on the first of every month. Robin lives in Houston and I live in Boston. We will be posting about what to do in the garden that month and giving advice. So if you have always wanted that vegetable garden, but didn’t know where to start, you have no excuse. Get growing!
Growing your own seedlings
Up north we are locked in ice still. There is no outside growing going on. Even the intrepid folks who have low hoops over their garden are just hoping everything lives through the cold of January. The one place we can start to think about growing is inside under lights.
Many people buy all their transplants from the garden center. I've certainly done that in many years, but doing so limits your choices. Tomatoes might be the one exception. For instance Verrill Farm in Concord, MA might sell 30 varieties of tomato transplants every year, but they only sell a couple of kinds of peppers. So if you want anything but Cherry Bomb or Jalapeno, you are out of luck. Looking in a lot of different garden centers can improve your odds of finding the pepper you want. But if you are looking to grow a Fish pepper, for a spicy white cream sauce, you will have to grow your own.
Lights
The best way to grow your own transplants is with artificial lights. You can do transplants using the natural light on a south facing windowsill, but I've found that the transplants are more leggy and not as strong. They succumb more easily to disease.
The LEDs were getting a lot of press, but I tried them and they aren't quite ready for prime time yet. Fluorescent shop lights however are cheap and easy to get. And best of all they really work well.
You can get shop lights at hardware stores and home improvement centers. You might even have one in your basement right now. Four foot long T8 lights give you the largest bang for the buck. Shop lights come with two bulbs in them. Some are spaced a couple of inches apart. Some are closer together. You want to pick the light with the bulbs spaced as far apart as possible. In addition you want a wide reflector. Your plants will grow best if they are right under the lights and if the lights are spaced farther apart you have a wider growing surface.
Many people buy full spectrum lights. Save your money if you are only growing transplants. The cheap cool white bulbs are perfect for leafy growth. The red part of the spectrum is only needed if you want to grow flowers. So I hear the question already, "What if I'm growing marigolds which are flowering plants?" Even flowering plants do better and have more blooms in their future if you transplant them young, before they bud out. So in their youth they only need blue.
The one thing you should spend money on is replacing your bulbs every couple of years. Fluorescent lights lose brightness over time. The less bright your bulbs are the weaker your transplants will be. Every time I do it, it seems really wasteful, but your plants will thank you. If you don't like throwing out bulbs that still work, I suggest putting them on Freecycle (remember fluorescent bulbs have mercury in them and should be thrown out with the rest of the garbage, my town has a toxic waste day where you can toss things like that and they will be processed appropriately).
Shoplight being used to grow seedlings
When you set up your lights, put them on chains (they often come with chains) so you can raise and lower the lights. It is best to always keep the lights about and inch or two above the plants. If the plants start to touch they can get burned. If they get too far away the plants will get leggy. You can attach them to anything (mine are on brackets in the wall), but most people use wire shelving rack that come 4' wide. You can just hook the chain onto the top shelf and grow on the shelf below. If you need even more space you can use all the shelves.
Where should your shelves be? They should be in a room that is not too hot and not too cold. This can mean a different temperature for different crops but I have found if your room is between 60F-75F (15C-21C) almost all the crops will grow. I have mine in my laundry room which maintains a temperature of about 62F (16C). Warm weather crops (tomatoes, peppers, and eggplants) will grow just fine as transplants there, but they won't germinate easily at that temperature. I own a heating mat and use it to make sure they germinate and remove it once they are up. If you don't want to spend the money on a heating mat, you can germinate the warm weather crops in a warm spot in your house. The top of the refrigerator often fits the bill. I've even used the back of my desk where the radiator heat comes up. Just make sure they get moved to the light the instant they pop out of the soil.
Except for onions (which bulb up due to the length of the day), you should keep your lights on for about 15 hours a day. I heartily recommend a timer so you don't forget to turn them on and off. Don't leave them on all night long as plants need a rest from the light.
Growing mixtures
You can't grow seedlings in your typical garden soil. Your garden soil is too heavy and has lots diseases and insect pests. Young seedlings are prone to damping off disease. Most people buy a sterile seed starting mix from the local garden center or hardware store. I heartily endorse the behavior for first time growers even if I don't always do it myself (mostly I make my own mix).
Containers
Once you have your soil, you have to find something to put it in. The only requirement is that it is deep enough (for many plants 2" is plenty) and it has holes in the bottom so it can drain well.
Onions growing in commercial cell packs
Commercially you can buy cell packs and trays. They have little dividers between plants so their roots don't get tangled. Plants find transplanting stressful (though different plants take the shock differently) and this separates the roots from one another to reduce the stress. You can also find peat pots and jiffy pots that reduce the stress even more. With these you don't even remove the plants from the pot. You plant them pot and all. I find them a bit on the expensive side. Peat pots I find have another problem too. The compressed peat is hard for the plant roots to get through and can slow down the plants rooting into the soil itself once it is planted. In addition the pot rim can wick up moisture from the soil and dry out the plant. I've found the plants just don't grow as well as other methods.
You do not have to spend money on pots however. You can make your own. You can make flats of plants (where the roots do grow together) from things like plastic clam shells from your recycle bin. You can use old cardboard boxes (but they wick water so need to be watered more often). You can use tossed plastic cups. These are all free. Once caveat is that you have to punch holes in the bottom so the water can drain out well.
A flat of newspaper pots waiting to be transplanted
Another homemade pot is the newspaper pot. Commercially they sell forms to make them quickly. In addition there are plenty of instructions online for how to make them, but you can also do it very simply like I do. I merely take a long strip of newspaper about three inches high and loop it around a bottle and use a paper clip or piece of masking tape to keep it from coming unraveled. I don't even have a bottom to the pots. I keep the soil in by compression. I compress the soil firmly into the bottom while keeping the pot down on the counter. Sometimes I lose a little dirt when watering, but mostly it stays together quite well. And once planted, the roots are instantly free to grow.
Soil blocker
Last year I started using soil block makers. Soil blocks are just compressed soil. They hold together because of the compression of the soil that has a lot of peat. They aren't as easy as other methods and have a learning curve. I found it took a while before I figured out just the right amount of water to add to the soil mix and how to get the soil compacted evenly across the blocker (I use my hands, though none of the instructions you will read will tell you to do this). In addition they are harder to water. I find bottom watering the simplest method, but you have to do it gently and not near a block so the soil from the blocks isn't washed away. Many say to use a mister to keep them moist, but my hands aren't strong enough to mist until all my blocks are moist all the way through. In addition the blockers needs a soil mix that will hold up to the blocker but drain well enough when compressed. The general advice is to make your own. I have done this and also used Fedco's Fort V potting mix. Both seem to work well though my homemade mix is cheaper. There are probably other brands that work well too, but since I haven't tried them I can't recommend them.
Soil blocks
So why would I go to the trouble of using a soil block if it is so hard? Well the best thing about a block is the it just gets planted right into the ground which means there is no transplant shock at all and the plants grow strongly as soon as they are planted. And unlike even a thin newspaper pot, there is nothing to break down before the roots can reach the soil. The roots instantly take off. So of all methods it is the hardest for the human, but the easiest on the plants. If you are interested in reading more about them PottingBlocks.com is a good reference site, but remember that it is a commercial site so has a vested interest in you buying something.
Watering and Fertilization
Many people just pour water over their seedlings to water. I don't recommend this. Fungal diseases are more common when the foliage of the plants get wet. We are indoors and there is no reason to do this to your plants. I recommend bottom watering. You will need a tray that is bigger than your pots. Pour water into the tray to about an inch and then gently sink your pots. When you see the top of the soil is wet, they have been watered sufficiently and you can remove them to drain. If you have blocks you need to be even more careful and put the blocks in a tray (I keep them in one) and slowly pour in the water so the stream doesn't hit any blocks. Only pour in a bit at a time and slowly let the blocks soak it up. You don't want to get the water to high or move very fast or the soil might wash away.
Before you water again let the surface of your pots dry out. If they stay wet all the time they will be more prone to damping off and mold will grow on the surface (most surface molds are harmless so don't worry too much about them). You never want to let it get dry enough that your seedlings wilt, but they do better if they aren't constantly soggy either.
I use a soil mixture that has enough organic fertilizer in it that I never need to add fertilizer while my seedlings are growing. I find this the easiest solution. Many seedling mixes will contain fertilizer too. If your soil mix doesn't have a fertilizer then you will need to fertilize your seedlings regularly with a balanced liquid fertilizer. You can do this whenever you water. The bottle will usually have a recommendation for how much to feed, but never use more than a half strength fertilizer on seedlings and don't start until they have their first true leaves. (The first leaves on a plant are called seed leaves and usually have a different shape than the leaves that will come next, or their true leaves.)
Keep the Seedling Healthy
Plants don't like the air to be absolutely still like it is indoors for two reasons. The first is if the air doesn't circulate, damping off is more likely to kill your plants. Damping off is a generic term for a lot of different fungal diseases, but they all have the same symptoms. The plant stem either at or just below the surface rots and the plant falls over. It is less common if the soil surface is kept dry (though a dry surface will not prevent it totally). So circulating air helps keep the soil from staying damp too long. There are some home preventatives (not cures, once your plants have this kind of rot on their stem they are dead - get rid of them before they infect their neighbors). If after you sow your seeds, you sprinkle the surface with cinnamon it will help prevent the disease. Also diluted chamomile tea works fairly well, if you put it into your watering can, or if you spray it lightly on the plants.
Air circulation is good for another reason. The stems of plants that are grown in air that is very still tend to be leggier (taller and thinner). They also don't have the strength to stand up to the wind when finally put outside. If the plants are grown with air movement they will be shorter and stockier and won't be as shocked when transplanted outside. Thigmomorphogenesis is the word that botanists use for this phenomena. Interestingly enough you don't really need wind. If you pet your plants, the touch of your hand will keep the plants from getting spindly too. But a small fan works really well. You don't want one that is very powerful. Heavy wind will set the plants back, but mild breeze will help them out. I use a cheap little $10 clip on fan. I don't keep it on all the time, but turn it on for an hour or so every couple of days usually right after I water.
What Plants and How Long They Grow Indoors
Not all seeds should be started indoors. Some like bean seeds hate to be transplanted and germinate well outdoors, so why bother. If you start them inside you have to be really careful not to disturb their roots at all and they still often do better direct seeded. The following is a list of the most common of these plants: beans, peas, spinach, corn, melons, cucumbers, and squash.
Some people elect to try to start them inside for the following reasons. Some winter squash has a long growing season and if the plants aren't given a head start they won't have time to ripen (a reason only for short growing seasons). An extra early harvest is another reason. Getting the plants big enough before they are put out so the slugs don't eat them to the ground before they get big enough (the reason I do this with cucumbers). Spinach sometimes has germination issues so they start them inside. I generally recommend not growing these indoors unless you have a solid reason for doing it. They are much easier as direct seeded plants. If you do elect to grow these indoors, make sure you use a pot that doesn't disturb the roots, like newspaper pots or soil blocks.
There is a list of plants that I would never transplant. These are typically root crops: carrots, beets, radishes, turnips, rutabaga, parsnips, dill, and cilantro. Root crops (with the exception of onions that are always done as transplants or sets) just hate being transplanted and sometimes will never form a good root if you do.
Then there are the seeds that are easily grown direct seeded in the garden, but do well as transplants too. Whether they are direct seeded or grown indoors is really an issue of your climate and the timing of when you want to get crops. If I grow successions of lettuce indoors I can get the seedlings older before they need space in the garden. Then they might only need to spend a month in the garden to head up instead of two. So sometimes growing seedlings indoors is just a space saver. Some use part of the garden as a nursery bed for just this reason. If your broccoli needs an 18”x18” spot in the garden, you might not want to give it that space until it needs it. You could grow something else there until your transplants are ready. But on with the list of crops in this type: lettuce, Asian greens, broccoli, cabbage. In the north the last three are almost always grown as transplants, but I see a lot of southern gardeners direct seed these crops as they have a longer season.
The last list is a list of the plants that people almost always grow from transplants or buy from a nursery. It really isn't necessary. Tomatoes will grow quite well from seed in the garden, but usually the seasons aren't long enough to get a crop before frost (or intense heat in the far south). These are peppers, tomatillos, tomatoes, onions, and eggplant.
How long should you grow these crops in pots indoors? Maybe people will say that tomatoes need 8 weeks before transplanting. This isn't necessarily true. It depends upon how big of a pot you it is grown in. A good rule is that transplants should never get root bound. Once the roots have filled up their pot they either need to go out into the garden or they need to be given a larger pot. If you don't do this the plant will get stressed and your yield will go down. So if you are only growing them in a small pot and don't want to pot up, you need to grow them for a shorter period of time. Smaller transplants can often grow better than larger ones. For some plants once they hit a certain stage in their growth they quite working on their roots and put their energies into their leaves or fruit. If you haven't gotten your plant into the garden by then you won't get a good root system and your harvest will suffer. Peppers are cruel this way. They tell you right when you've waited too long. Once they start flowering they have gotten a bit too old. I still plant peppers that have started flowering out in the garden, but I really try to make sure they haven't started yet.
Below is how long to grow your transplants.
Plant | How long to grow in weeks | When to plant after last frost | Careful of roots | Needs heat to germinate |
| Basil | 5 to 6 | 2 |
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| Broccoli | 3 to 6 | -2 to 0 |
|
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| Chinese Cabbage | 3 to 6 | 0 |
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| Cabbage | 3 to 6 | -2 to 0 |
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| Chard | 3 to 4 | -2 to 0 |
|
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| Cucumbers | 2 to 3 | 2 | yes | yes |
| Eggplant | 3 to 6 | 4 |
| yes |
| Kale | 3 to 6 | -2 to 0 |
|
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| Leeks | 8 to 12 | -2 to 0 |
|
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| Lettuce | 3 to 5 | -2 to 0 |
|
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| Melon | 2 to 4 | 4 | yes | yes |
| Onions | 8 to 10 | -2 to 0 |
|
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| Peppers | 4 to 7 | 2 |
| yes |
| Squash | 2 to 3 | 2 | yes | yes |
| Tomatillo | 4 to 8* | 0 |
| yes |
| Tomatoes | 4 to 6 | 2 |
| yes |
*I've found tomatillos a little problematic on timing. Some can germinate in a few days (like most seeds) and some can take several weeks. If yours germinates quickly the timing might be shorter, or if they are very slow they might be longer.
You will notice that some of the cold hardy plants say you can plant them at your last frost date or a couple of weeks before this date. The variable is how well you harden off your plants before setting them out. If a plant is grown indoors in a nice controlled environment than is just planted outside it can easily succumb to the harsh conditions. If you slowly acclimatize the plant to the weather the plant will learn how to deal with the temperature swings and cold temperatures. I'll talk more about transplanting and hardening off later in the year.
The other variable is how long to grow the plants. Typically the lower range is if you only give them a smaller pot to grow in, say 1 1/2” square. The second number is if you pot them up (move them to a bigger pot) to a 4” pot. I often pot up into deep newspaper pots, but however you do it the roots need more space once they fill out the pots they are in.
The plants that don't like root disturbance like the squash should never be potted up. Start with a larger pot. I use a 4” tall and 3” wide newspaper pot. You want to see at least the first true leaf before planting out, but no more than two true leaves. Shorter is often better with these types of plants.
When you pot up your plants make sure they are growing in their new pot at the same level they were growing in their old pot. Some plants will die if they are sunk too deep into the pots. The major exception is tomatoes. For tomatoes you can plant the low into the new pot. A tomato plant will put out roots all along the stem, so it only makes the plant stronger.
The last thing you need to know to calculate when you want to start your plants is your last frost date. Robin talked about this last month, but because it is so important I'm going to talk about it again.
Your last frost date is something you will learn over time. There are some wonderful charts out there that will tell you what it is, but every location is slightly different. For instance I live on a steep hill. Cold air sinks so the colder frosty air just flows right down the hill to the valley. Just a few hundred yards from my house could have a frost weeks after I have had my last one. Robin had a good link in her December post. My favorite frost chart is here. Just scroll to your state and click on it. It will bring you to a page that lists where all the official weather stations in your state are. Find the one closest to you for an idea of when last frost is. Use the average 36F degree row since frost can easily occur when the thermometer reads over 32F (remember cold air sinks and readings are usually not taken right at the ground level).
Other post in the series
Determining your growing zone and planting peas (Vegetable Matter - December)
Planning a Garden (Daphne's Dandelions - December)
Growing Lettuce (Vegetable Matter - January)
Starting transplants indoors (Daphne's Dandelions - January)
Growing tomatoes (Vegetable Matter - February)
Compost (Daphne's Dandelions - February)
Snap Beans (Vegetable Matter - March)
Peas and Spinach (Daphne's Dandelions - March)
Eggplant (Vegetable Matter - April)
Brassicas (Broccoli, Cabbage, Asian vegetables) (Daphne's Dandelions - April)
Edamame (Vegetable Matter - May)
Tomatoes (Daphne's Dandelions - May)
I spent only $33.80 on seeds from Fedco. That isn't a lot of seed is it? They give free shipping for orders over $30 so I had to buy at least that much. When they came earlier this week I was overjoyed. Then I noticed three in back order. My zucchini and winter squash are no problem. I won't need them for quite a while. But the last was Varsity, an onion. Ack! They send a letter with your order which talks about what is going on at Fedco. What seeds have run out etc. In addition they said six varieties of onion were on backstock. They swear to drop everything once they come in so they can get shipped out. They know we need to start them soon. Yes! I do! At least they know it is an issue. I hope they come soon since they need to get started in a couple of weeks. I'm not freaking out quite yet.
Then the next day another set of seeds showed up. My wintersown seeds. They will let you choose six packets of tomato seeds if you go through their little wintersown quiz. They have lots to seeds to choose from. This year I picked out all paste tomatoes and good canning tomatoes. I got tired of making sauce out of cherry tomatoes last year. Really it isn't the way to do it. Of course they didn't send me just the six that I chose, but they sent me eight tomatoes plus two other packets. The flat leafed parsley isn't really necessary, but I'll grow a few to add to my self sowing flat leafed parsley. I figure a gene infusion can't hurt. Especially since this coming year is an off year for my parsley. Being a biennial and self sowing in my garden, certain years are better than others. The other was Lemon Queen Sunflowers. Score! I grew them last year for the Great Sunflower Project, but the seeds they send are terrible and few. This ought to get a better stand of them in the garden.
