Propagating From Seed
Your seed has just arrived in the mail! Or it has been carefully collected and saved from the previous season. You want to ensure that it is sown in such a way that you increase if not guarantee its chance of survival and development into a mature plant.
When to sow
The first thing that you need to know before starting your seeds is your local "last frost date". This is the date that you work backwards from to figure out when to sow your seeds. However, this is not a date etched in stone, some years it may be earlier, and there is always a chance of a light frost after this date. If you want to gamble and get some plants out early- be prepared with some protection, ie remay covers, plastic milk bottles, etc. To help you figure out your last frost date here are links to the Farmer's Almanac Charts for Canada and the US.
Last Frost Date for Canadian Cities
As a general rule, sow seeds indoors six to eight weeks before the last frost date. Information on the seed packet is your best guide in knowing when to sow. Time indoor plantings so that your seedlings do not outgrow their containers before it is time to plant them out in the garden. Seedlings kept indoors too long will be weak; they will grow slowly and bloom poorly. I know how tempting it is to get started, but to avoid having to manage huge plants inside, it is better to start a little late, than too early. Some of the most rewarding plants to start inside early are the herbs. Anise hyssop smells great even as soon as the seedling leaves appear. And can you ever have too much basil?
Sowing the seed
I utilize two different types of containers to start my seeds. One is a plastic cellpack 3" X 5", the other is a ziplock bag. I start my seeds in a sterile medium in a clean container. Make sure that you choose a container at least 2 inches deep with drainage holes— a clear-lidded deli container with holes punched in the bottom is one of the best freebies you can use. This is one place where it does pay to buy proper containers. Try to limit yourself to one variety of seed per container - you are only using this first container to germinate the seed and grow it on till it has its second set of leaves. Since different plants will germinate at different rates, it makes life much simpler if you have only one type per container. Later, you'll need to transfer the seedlings to small individual pots or multi-cell packs, or even flats if you're growing larger quantities. I do not recommend using peat pots or the little jiffy pots - I have not had much success with them and they seem to dry out way too quickly- (miss a day of watering these guys and you risk losing all your plants!) If I am reusing cellpacks from previous years, I wash them first in a solution of 1 part bleach to 10 parts water. I fill the cellpacks two-thirds full with pre-moistened potting mix (To avoid disease problems, use fresh potting mix. Commercial seed-starting mixes are usually blended from finely milled sphagnum peat moss and vermiculite. Soil-less houseplant mixes containing perlite, vermiculite, and peat moss work well, too), firm gently with the bottom of another cell pack, and the top third with moist vermiculite. I usually indent slightly three rows lengthwise and sow approximately 10 seeds per row, or 30 seeds per container. If I have very large seeds, I may only sow 5-7 seeds per row. I then barely cover the seeds with vermiculite (I use the horticultural grade, as it comes in small particles and is easy to work with), and if they are going outside, or if the seeds take a long time to germinate I then cover them with a 1/8 - 1/4 inch layer of chicken grit or finely ground granite chips. This will help protect the seeds and help prevent the growth of mold and or algae.
Labelling the containers
I use two methods to label the containers. I mark the name of the seed, and the date with pencil on cut-up mini blinds or on masking tape. Pencil is better than pen or marker, as it doesn't fade and can last years.
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Seed containers protected from heavy frosts with recycled styrofoam grape containers from the grocery store. I then put a sheet of bubble wrap over this. Note the 'mini-blind' labels. |
After they have been labelled I place the containers in a shallow tray filled with lukewarm water. After they have soaked up enough moisture I remove them and let them drain. You want the medium to remain moist until the seeds have germinated, but you don't want it so wet that it will encourage mold, or even the seeds to rot. I then place the seed containers in a flat that has no drainage holes (so I can water from the bottom) if they are being kept inside, and a flat WITH drainage holes if they are going outside into the cold frame. I then place a clear plastic dome over the flat to retain moisture- you do NOT want the seeds to dry out at this stage!
One of the challenges of seed-sowing is figuring out the best conditions and or temperature to provide the seeds to help them germinate. Ideally your seed packet has come with instructions that you can just follow. For instance, many seeds respond well to bottom heat. One of the best investments that I have made is a small propagation system, basically a styrofoam box with a heating pad in the bottom and a clear plastic dome cover. I bought mine at Home Depot. I also use the top of my fluorescent light fixtures to provide bottom heat.
Using the 'Paper-towel' Method
For many traditionally 'difficult' seeds I use the paper-towel method. This is no more complicated than placing the seeds on a moistened paper towel (I prefer to use coffee filters-as they don't break down as quickly), placing another papertowel/filter on top, and then carefully folding the towel/filter in on itself and placing it in a ziplock bag marked with a Sharpie or other indelible marker -don't forget to mark the date too. I stack several of these in styrofoam or deli containers, and place on top of my fluorescent light fixtures. The top of the fridge, by a furnace vent, or someplace fairly warm will also work. If you stack them on end instead of on top of each other as I did in the picture, you will have the heat evenly distributed to all the bags.
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Transplanting the seedlings
Germinating the seeds is only the first step, once the seeds in the cell packs have formed the first true set of leaves (which come after the seed leaves), it's time to transplant them into containers that will give them more room to grow. Or, once the seeds in the paper towel/filter have sent out a radicle or seed root, it's time to pot them up. I use various sized pots for this step. Sometimes I pot them into cellpacks divided into individual section, sometimes I use the 3" X 5" pots again and plant 5-6 seedlings per pot, sometimes I use 2" pots and for very large seeds with big seedlings, like gourds, I may even go up to a 4" pot right away. To transplant seedlings, carefully lift plants by their leaves (not stems), I use a small mini-blind label that has been cut to a rounded point at one end to help dig them out if necessaryl. Replant them in moist, all-purpose potting soil at the same depth they grew before or slightly deeper.
At this stage, many seedlings grow best at cooler temperatures. It is also important that they have strong enough light. Otherwise you can have weak plants with elongated stems. Bright light is the key to growing sturdy, healthy seedlings indoors. If you live where late winter days are often cloudy, even a south-facing window may not provide enough light for your seedlings. Consider supplementing natural light with a fluorescent shop light, hung so the tubes are just an inch or two above the leaves. Wide-spectrum tubes come closest to duplicating sunlight, but cool white tubes give similar results at a fraction of the cost. Make sure that the tubes are cleaned of dust. Connect your shop light to an automatic timer that switches the light on for 14 to 16 hours a day. This is also the first time that they need fertilizer. I water with a seaweed fertilizer- using a Haws watering can with a very fine rose so that the seedlings aren't washed away. Note in the pictures how close I have the plants to the light fixture- I use upturned flats to prop them up.
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In the picture on the right, I have a plastic dome covering containers that have seeds that are irregular germinators- some seeds have already germinated, but most have not. Or they are seeds that require light to germinate. Look for the high clear domes like this one- they are another great investment- about $5-6 Can, and they can be washed and reused year after year. Once humidity forms on the inside of the dome like this, I prop it up until it clears up and then close it again - again you don;t want to encourage rot. At this stage, good air circulation is important- I have an outside door right next to my plant light structure and several times a day I swing it open and closed- helps cool down the air temp too! A fan is also a good idea!
Hardening off the transplants
Tender annuals won't tolerate frost, so wait until winter is gone for good before setting your transplants out in the garden. Gradually acclimate your seedlings to outdoor weather over a period of one or two weeks. Start by setting the seedling flats in a shady, protected location for an hour or two a day. A coldframe facilitates the acclimation to outdoors, but any spot protected from wind and strong sunlight will do. Gradually increase the amount of time the seedlings spend outdoors and their exposure to sunlight. If you have a cart or wheelbarrow, you can just wheel them out and then back in. One of the easiest temporary cold frame/shelters to build is the polytunnel. I use rebar inserted into the ground two feet apart lengthwise and widthways about four feet apart, so for a eight foot long polytunnel, I have ten pieces of rebar stuck in the ground- 5 on each side (two feet apart) and each side is four feet away from the other. Then I use PVC pipe (the same width as the rebar) but long enough to make a semi-circle shape when each end is slid over the rebar (the rebar holds the PVC securely to the ground). Then a 10 foot wide and at least 12 foot long piece of plastic is draped over the hoops. I use bricks and long pieces of wood to hold down the plastic. When the sun shines and the weather warms up, it is important to open the ends and perhaps roll up the sides, so that the plants don't fry in there.