Here in northern New York, it is not uncommon for the last frost of the season to come as late as the beginning or even middle of June. Gardeners are forced to somehow extend their growing season, if their vegetable plants and ornamentals are going to produce ripe fruit or flowers. It is germinating seeds indoors, weeks or even months before the last frost, which enables gardeners in northern climes to compensate for the brevity of their growing season.
Starting seeds indoors provides the opportunity to choose varieties
that otherwise could not be grown. But, if you select shorter season
varieties that don't necessarily need to be started really early indoors, you can be just a few weeks away from your first batch of red, ripe tomatoes, for example, when other gardeners are still setting out small, immature, transplants. What's more, by starting early maturing plants at say, 10-day intervals, not only can you harvest early, you can harvest over an extended period of time.
When starting seeds indoors, cleanliness and sterilization of
materials is extremely important. Tools and containers should be
sterilized by thoroughly washing them with soap and water, removing
any debris, and then rinsing them in a solution of one part bleach
to ten or more parts water.
You can make your own starting flats out of egg cartons. Before
adding your planting medium, put a drainage hole in the bottom of
each compartment. Then, remove the lid and place it underneath the
bottom half to catch and hold any overflow of water. The individual
compartments are shallow, so they tend to dry out quickly and need to
be watered often. After the initial watering, putting your homemade
flats into clear plastic bags will allow you to maintain moisture. The plastic should be kept a minimum of an inch to an inch and a half from the soil. Avoid placing them in direct sunlight. The temperature could rise to dangerous levels. Be sure to remove the plastic bags as soon as the first seedlings appear. Plants that are started in flats should later be transplanted into individual pots.
Plastic starting "greenhouses" are nothing more than manufactured
flats. They are excellent for starting plants that can be easily transplanted. They can have any number of compartments and usually come with drip trays and covers. These work well and take up very little space.
Direct seeding into pots may be preferred, however. I've seen many
items used as containers for starting seeds; cottage cheese, sour cream and yogurt containers, for example. All work well, if they are used properly. Milk jugs can be cut in half, with the bottom half being used to hold your starting medium and the top half used as a cover, to hold in humidity. Holes must be placed in the bottom of all containers to allow proper drainage.
I favor using peat pots, which are biodegradable and can be transplanted with the seedlings so plant roots are not disturbed when transplanting. They provide excellent drainage and air movement, too.
Commercial peat pellets are another option. You simply drop the seeds into the top of the pellet and place the pellet on a tray. When you
add water, the pellet expands to a diameter of up to 1 3/4 inches
wide by 2 1/2 inches high. Many peat pellets already contain vitamins
and minerals, and since the entire pellet is transplanted with the seedling, there is no transplant shock.
Inexpensive foil pans can be used as drip trays for holding peat pellets, pots, flats or containers. Seeds need to be kept constantly moist in order to germinate, and drip trays allow for bottom watering.
Be careful, however, to keep water from sitting in the drip trays and always use care and good judgment when surface watering. If soil
becomes waterlogged, seedlings will suffer. Keep in mind, too, that
round containers waste more space than square or rectangular ones.
While it's fine to start your seeds in recycled, sterilized containers, you should certainly think twice about using your own soil. Soil (including potting soil) is often prone to compaction, which can stunt seedling growth. And soil that has not been sterilized presents a risk of contamination due to disease-causing organisms. Yes, yard and garden soil can be sterilized, but the process, slowly baking it in an oven until the soil temperature is between 160 and 180 degrees, can be somewhat sickening. You will want to do it on a day when you can open the windows. The soil must be moist, but not wet, and it must be kept covered while it is baking, so it does not dry out too quickly.
I like using commercial potting mixes (not soils) that are readily
available at local garden centers. A suitable growing medium should
be very light, pliable and able to hold moisture.
When planting, moisten your potting medium thoroughly before you sow. Mix it well to distribute the moisture evenly. Containers should be filled to within 3/4 of an inch of the top with moistened, sterile medium. For very small seeds, the top 1/4 inch should be of a fine, screened mix or a layer of vermiculite. Keep in mind that a deeper container requires more growing medium and will weigh more.
I like to recommend putting two seeds in each compartment, container, peat pot or peat pellet. Containers should be covered with plastic to allow for retention of moisture. Your planting medium must remain warm and moist, but not wet. You should remove plastic covers once the seeds have sprouted, but you must be sure that the soil remains moist. Watering with a plastic spray bottle will help you avoid displacing soil, which could disturb seeds or the roots of started plants. Always use water that is room temperature.
If two plants are growing in one container, save only the healthiest
plant. Pulling out the undesired plant is not advised, as this could result in damage to the roots of the seedling that you are keeping. It is best to cut them down with a sharp scissors.
Besides needing good soil and the right amount of water, plants require a lot of light. Seedlings receiving insufficient light become tall and spindly and will remain pale and weak. A south-facing window that provides full sun may be adequate if days are sunny and bright, but you must be sure that the windowsill doesn't become too cool at night.
Many gardeners find it necessary to supplement with artificial light.
I don't have very good light in my home because I'm surrounded by
conifers, so I choose to use only artificial light. That's the beauty
of it, you can set up a grow light system anywhere, even in your
basement or heated garage. Use bulbs that are made specifically for
growing plants.
Fluorescent tubes are almost certainly the safest form of artificial
lighting because they produce very little heat, which can quickly dry
out seedlings. I like to place the fluorescent tubes as close as possible to my seedlings and carefully raise them, as the seedlings grow taller, providing them with a minimum of 14 hours of light daily and remaining vigilant about maintaining the moisture in the soil.
Other gardeners recommend keeping the tubes 10 inches or more above the plants at all times, so there is ample room for growth.
Forty-watt, double light (shop light) fluorescent fixtures are
inexpensive, and building a low cost frame for a grow light fixture is
easy to do. The Clinton County Master Gardeners have produced a fact sheet on building one and I'd be happy to send it to you.
As your plants start to outgrow the starter compartments or containers, you should transplant into bigger pots. As your seedlings near the final transplanting stage, you may want to start using a weak solution of water soluble fertilizer (no more than half the recommended strength), once or twice a week when watering. Slowly
increase the amount of fertilizer used, until you are providing food as per the manufacturer's directions.
It is a good practice to acclimatize transplants grown under nursery
conditions, before putting them into the ground. This practice, known
as hardening off, will enable seedlings to withstand exposure to the elements. Choose a sheltered, somewhat shaded area and a sunny
afternoon. The first time you put your plants outside, put them out for only an hour or two. Steadily increase the amount of time that they are kept outdoors, until you are finally leaving them out overnight. It should take seven to10 days to harden off your plants.
Slower is better. If the transition is too fast and/or seedlings are not kept well watered, plants will become stressed and may even wilt. Place them in a cold frame if you prefer, or if frost is expected.
Once you can be sure that the danger of frost is past, you may set your plants in the ground. I find it best to choose a late afternoon on an overcast day. First, dig your holes. Then very carefully remove the plants from the flats or containers, keeping the soil around the roots intact and taking extra care not to handle the root balls, if at all possible. This is best accomplished by keeping the soil around the roots moist, but not wet. Fine root hairs are extremely fragile and roots should be exposed to the air no more than is necessary. Set each plant in a prepared hole and tamp the dirt firmly around it.
Then water it well. This will assure good earth to root contact and eliminate air pockets.
If you would like to learn more about season extension, please join
me at 1 p.m. March 7 at The Wild Center in Tupper Lake for
presentations and conversation on extending the growing season.
For more information, contact me at 483-7403 or rlg24@cornell.edu or visit the Wild Center Web site, ww.wildcenter.org, and click on the
events link.
Happy gardening!