Starting plants indoors, whether in the house or in a greenhouse, gives you a jump on the upcoming garden season. Generally speaking unless you have a south-southwesterly facing window, starting indoors in your house is an “iffy” situation largely for two reasons: Firstly, the air of the average home is too dry in these early winter days with a humidity level of only 32%; secondly, plants tend to reach for the sun and gradually become too leggy to support themselves. These disadvantages can be somewhat compensated for by tenting clear plastic over your growing area, and misting your “plant-lings” several times a day. Many people try to just continually water their plants but this only leads to soggy soil and promotes failure in the form of rot and damping off disease. Growing indoors I also find very labor intensive as you have to monitor plants continually for optimum growing conditions.
Largely because of the foregoing I built a small lean-to greenhouse onto my basement wall with a direct southern exposure. I used mainly scrap and discarded materials to make it and the biggest cost was in muscle power in digging out the footprint of a 10×10’ layout down to an average of four feet. Now I not only start my seedlings here but also winter over some of my plants from the summer season.
The greenhouse is equipped with a hose bib and heat so all I need do is water the plants with the hose every 3 days. The optimum humidity is provided by the water that seeps to the floor and evaporates into the enclosed atmosphere. It remains in the range of 70% humidity throughout the winter. In addition, I have an aquarium, without filtration, in which I grow water cress for winter salads and contain the few goldfish from my small 100 gallon outdoor goldfish pond on the patio. The fish winter over here and also keep all the flora and fauna under control such as algae and mosquitoes.
Transplants are normally started several weeks before being transplanted outdoors. Look for the instructions on the seed plants to determine the ideal time. For those of us who have saved seed and no longer have the seed packets as a guide here is a handy guide to help you determine the time of seed starting to transplant. You must also be aware of the last frost dates for your area to determine the best seed starting times.
Celeriac and celery are from 7 to 12 weeks from seed to transplant;
Onions (seeds, not sets) and parsley are from 8 to 10 weeks;
Nightshade family, i.e. tomatoes, peppers, and eggplant is 6 to 8 weeks, though these are often started in flats and transferred to individual pots within the greenhouse after good growth is achieved;
Broccoli, Brussels sprouts, cabbage, cauliflower, Chinese cabbage, collards, and watermelon are from 5 to 7 weeks;
Sweet potato tubers, cantaloupe, and other muskmelons, cucumbers, and summer and winter squash are from 3-4 weeks.
With the exception of sweet potatoes it is generally not a good idea to plant root crop seedlings; this will often result in crooked and deformed root growth.
It is tempting to want to start seeds when the winter doldrums set in in late January or February, but unless you are in the Deep South resist this temptation because it will prove unproductive in the long run and result in discouragement. Stick to the above plan and you should be successful and you will not need to buy plants after the weather turns warm.
Richard of Danbury, D.S.G.