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Gathering seeds is a matter of timing. For each plant, there is one time when the seeds have matured and have not yet been distributed by nature in the manner intended by the design of the seed pod, the flower head, or the seed itself. If the flower head has dried and turned brown on the stem, or if the seed pods have turned brown and are starting to split open, or you can hear the seeds rattle when you shake the pod, or if you can see that animals or birds are eating the fruit, then the seeds are ready to gather. Gather the seeds prematurely, and you make the task of cleaning the seed both difficult and time consuming. Wait too long, and the seeds will have dropped to the ground, flown away in the wind, been broadcast by exploding seed pods, or eaten. Determining the correct time to gather mature seeds is done by careful observation. There is no substitute for observation. Example #1: from Aster crego to Classic zinnia, there are any number of plants that are still in full bloom on the day of your first killing frost. There is little to gain by collecting the flower heads when 5 or 10% of the seeds have ripened. Wait until the first nice day in February to collect those flower heads; they may have been frozen in time, but now all the seeds will have ripened and be easier to extract. Example #2: You want to save seeds from your eggplant or squash. The seeds from either are immature when the fruit is ripe enough for you to eat. Collect your seed from these mature oversize seed pods after they have been left in the garden fully a month after you have cleaned up in preparation for winter. Nature considers these seeds to be ripe about the time their containers have been destroyed by the weather. Note that there is minimum of thirty days difference between deadheading flowers to promote additional flowering and cutting flower heads for seed collection.
When you have decided to collect the seeds for a particular plant, cut the stems, invert them, and shake against the inside of the bucket. If most of the seeds fall into the bucket, you have found the method for that type of plant. In few cases, will the flower heads have to be shredded before they will release their seeds. In the case of fruit or vegetables, the seeds will have to be extracted with mechanical assistance much of the time. If the work is tedious and seems not worth the effort, either your timing or your method need to be improved. Example: you have collected the blackened heads of purple coneflowers, but prying the seeds out is a chore. Simply leave the heads out in freezing weather, and in time, all the seeds will have extracted themselves into your container. Another example: puree a whole tomato in your food processor; poor the contents into a glass; cover with a paper towel; let sit for three or four days to ferment; strain out and dry the seeds for storage. Put nature to work for you whenever possible.
You will pay a high price for careless collection technique or timing, in that your cleaning chore is multiplied from 10 to 100 fold. Seventy-five percent of all the seeds I collect require no cleaning whatever because I use the right moment and the right method. Do not snip off flower heads into a paper bag. That is the surest method of losing the seeds to mold; and it is guaranteed to make seed cleaning the most time consuming chore you encounter all year long. Examine the flower head or seed pod carefully. Think! Use your head to tap-out, blow-out, or pluck-out just the mature fully ripened seeds without any chaff.
I purchased stainless steel mesh (12" x 12" pieces) in eleven sizes from the local industrial supply house. In terms of the number of squares per inch, I have the following sizes: 4, 6, 8, 10, 12, 14, 16, 18, 20, 24 and 30. #4 is the most useful size for beans, while #30 is suitable for very small seed like Begonias. Careful collection techniques will minimize the cleaning chore. As a general rule, for each type of seed, you will need three sieves. First, run the seeds through the sieve whose holes are just larger than your largest seed; that will clear away the large chaff from the seed. Next run the seed through the sieve whose holes will pass 95% of the seeds; that will clear away the smaller debris. Next run the seed against the sieve whose holes are smaller than your smallest seed; that will clear away the dust. Any chaff that remains is the same size as the seed. If the quantity of chaff remaining is objectionable, switch to the fan method for the last step. To use the fan method, simply pour the seed from one tray to another with air flowing through the space between the trays. Start at some distance from the fan so that the chaff will be blown away rather than the seed. Gradually move closer to the fan as you pour the seeds through the air stream until you are satisfied with the result. The seed loss possible with the fan method is unlimited, unless you take care and work slowly.
Another method that works well for me, especially for small seeds equipped with a plumelike pappus (parasails) such as Aster, Eupatorium, and Solidago, is to rub the collection against the surface of a #18 screen and then a #30 screen. This separates the seeds from the parasails quickly. The resulting chaff is the same size as the seeds, but of lighter weight. Whenever you have seeds and chaff so small as to prohibit the fan method of separating chaff, use a vibration box. Any rigid tray will do, but metal is probably best as it is less likely to accumulate static charges which can be annoying. I polish my plastic trays and tubs used for seed processing with an aerosol anti-static spray several times each season to remove static. Alternately throw the mess against the far wall of the tray or tap on the sides. The seeds will accumulate at the bottom while the lighter chaff will continuously migrate upward towards the far wall.
Throughout the seed cleaning process, keep in mind that your objective is to separate as much debris as possible, but within reason. If you lose 5% of the oversize seed and 5% of the undersized seed, your methods are probably consistent with the economical use of your time and energy. One of my favorite tools is a pharmaceutical pill counter, not for counting seeds, but for pouring seeds into small envelopes. Since these are promotional items given to pharmacies by the drug companies, your local pharmacy should have several to spare.
While some collectors prefer foil, and some prefer plastic zippered bags, my preference is for glassine envelopes. Small envelopes can be hard to find. See my seed envelope page for some places to check if you have had no luck:
Damp seed cannot be stored. Dry the seed for several days on a newspaper before bagging. Seeds in berries should be extracted and washed first. A small marine or RV type refrigerator in your garden room, some 3 x 5 card file boxes, and a supply of small envelopes work the best. My seeds are refrigerated as soon as they have been packaged and labeled. A good size envelope is something between 1.5" x 3½" and 2" x 4". This advice is for the efficient storage of 100 to 400 types of seed, along with your seed potatoes for next season. Smaller volume seed savers can simply use a drawer in the coolest room of the house. The card file boxes make it possible to store the seed packets in alphabetic order. The seed potatoes can be stored in cloth bags in the refrigerator door shelves. They will hold best if sprinkled with a small quantity of captan. These small refrigerators are inexpensive, trouble free, and draw only about 2.4 amps of household current when running; much less than your kitchen refrigerator. For more information about seed storage and seed life, go to Travis Saling's homepage at: http://www.rainyside.com/resources/faq_seeds.html
Now that your seeds have been collected, cleaned, and stored in alphabetic order, it is time to take inventory. Set up a database file with your word processor suite of programs if you have more than fifty types of seed. Include all of the pertinent information about germination requirements of each seed type, especially the number of weeks before or after last frost when the seeds are to be sown. Later, you will print out this list in the order in which the seeds must be sown, but meanwhile, you can select those seeds that you are willing to trade (assuming that you have more than you can use.) Prepare a separate list of seeds for trade. Bulletin board type of seed trading can be found at numerous sites on the internet.
If you are searching for a particular seed, for example, you can go to the gardener's exchange . At this location, you can first search all previous postings to see if anyone has offered the seed you are looking for, and then correspond with them via e-mail. You can describe the seeds you have to offer in trade, and the seeds you are looking for. Regular readers who have that seed will respond. This is the place to search for hard to find seeds. Gardeners are the most helpful people in the world. From time to time, you might get a request for seeds from someone who has no seeds to trade. You can ask for postage in advance, or you can be generous, depending upon available seeds, packing materials, and your ability to absorb the expense.
I suggest that you avoid offering seed which you purchased years ago, but no longer want; similarly, I would not like to receive saved seed more than two years old. For a fair trade, offer seeds which you have collected and cleaned from only the most recent growing season. The number of varieties or the number of seeds per variety traded are of less consequence than equalizing the postage expense of each party to the trade. A small postal scale will quickly identify shipments requiring more than one postage stamp. Seeds must be shipped in protective envelopes using air bubble or other type padding in order to protect from damage. These are readily available in office supply stores.
Many good books have been written to serve this topic. To avoid duplication, I will simply describe some of the principles I follow which make it possible to raise over 2000 plants from seed every spring in a garden room, only 8 x 14 ft.
To start, you must do the research on the germination requirements of each seed type. There is neither the space nor the time for experimentation if you plan to start as many seeds as I do. A precise schedule for sowing week by week is an absolute necessity. View the WKS_BLF file for zone 5a on page49.html. The weeks before last frost table that you develop for your FDA zone will become the heart of your seed-sowing management. You can operate from hand written notes or 3 x 5 cards for up to about fifty seed types. Over fifty types of seed require computer assisted lists or all will be chaos. My seed inventory and seed start scheduling database is indispensable in my germination room. A copy of this database is available at page48.html . Germination requirements for over 700 seed types are included along with sowing dates, transplanting instructions, and culture notes.
Where are the answers? Some seedsmen provide excellent and complete germination data on the seed packets. Some are notorious for little or no information. Some don't even identify annuals and perennials. Others won't even give you the botanical name of the plant. Be smart, don't buy seed from companies that fail to give you the whole story. More starter information is available in some seed catalogs than on the seed packets from the same company. You can use those catalogs to fill in the information gaps quite often. A simple query to one of the gardening forums will result in a mailbox full of answers, all different. But, you can average out the recommended procedure from the replies, and develop a germination plan for that seed.
If you plan to start more than 50 varieties of seed, I recommend standard 1020 trays with germination domes, and square plastic pots. There are many styles of trays, pots, and germination structures. It is best to specialize on one style so that it will be economic to purchase materials by the case. Standardize your inventory of pots to about 3 sizes. Discard all the oddball sizes, or make use of them elsewhere (but, keep them out of the germination and growing room, if you have big plans but little space.)
An unheated greenhouse is useful for starting the seeds of alpine and rock garden plants, hardening off plants, and for staging plants, but of little use as a germination room here in zone 5. Unless your greenhouse will have heat and running water, don't build yourself a glorified cold frame to sit there collecting spiders 8 months of the year. Solve the heating, ventilation, and insulation problems and their associated costs before you begin to build that white elephant. In many cases it would be better to build an add-on room or to convert an existing room into a garden room. Ideal temperature for a garden room ranges from 40º at night to 60º during the day. If the temperature or relative humidity exceed 60º or 60%, respectively, indoor air should be exchanged with outdoor until no further improvement may be obtained. Seeds that require 70º to 80º soil for germination should be brought indoors until they sprout, then returned to the garden room for growing along with the rest of the plants. Seeds which are planted on the surface because they need light to germinate, need not be put under strong light at first. They will germinate with ambient light. Seeds that call for darkness, must be checked every day for the first sign of germination, and promptly moved under lights.
If your seed starting results are less than satisfactory each year, pay a visit to a commercial greenhouse, where the problems have to be solved on a massive scale because of the investment at risk. Emulate what you observe there and in nature. Don't look at the plants, like everyone else. Look at the procedures. Look at the scheduling devices. Look at the mechanical equipment. Look at the physical plant. If it can make a profit, the combination of equipment and procedure must be cost-effective. That means that those principles will work for you too, scaled down to suit your space. There is nothing magical about starting seeds. If there is a secret, it must be attention to detail.
Find out which seeds are very sensitive to damping-off after germination. Then, pretend that all seeds are somewhat sensitive The prevention of damping-off requires some discipline and adherence to these principles: (1) Use sterile germination mixes containing no soil. I use Sunshine plug mix #5. There are many good brands. In quantities of less than one bale, they can get rather expensive. I augment this mix for most (but not all) seeds as follows: 4 parts mix plus one half part vermiculite (to retain moisture) and two parts Krum or perlite (for better drainage and aeration). The additions are made to the mix primarily to render it less expensive and to reduce the drain of one of our scarce resources (peat). Best of all, it never has to be pre-moistened before sowing seeds, because the mix absorbs water (even cool water) from the bottom, very rapidly. Bottom absorption is my first priority in selecting a mix. (2) Clean all pots and trays at the end of each season. (3) Always water from the bottom. (4) Provide constant , but indirect, air movement over the plants, 24 hrs. per day. If you ever tour a commercial greenhouse, you could not fail to be impressed by the magnitude of their air handling equipment. Similarly, you can feel the air on your face with every step taken in enclosed botanical gardens. There are several strong reasons (mostly disease prevention) for providing this much air, or commercial operators wouldn't bother. (5) Finally, if you are not averse to the use of fungicides, make up very small quantities of Captan solution to spray on seedlings which are known to be ultra sensitive to damping-off. I use about 1/8th teaspoon of Captan in four ounces of water to spray on sensitive plants germinating in cool wet conditions or on plants with germination times exceeding 15 days. Just a few examples: Allysum, Amaranthus, Coleus, Gerbera, Impatiens, and Tomato. I normally shun the use of chemicals, but fungicides to fight damping-off, cedar-apple rust, or mildew can be time-saving to say the least. Fungicidal sprays can be used without harm to beneficial insects, birds, and snakes with responsible application and proper timing.
Harden off your transplants first in the shade, second in the wind, and third in the sun for short periods until they demonstrate their ability to handle sunshine. I use rolling carts and platforms to move the transplants about until they are ready. My carport and an 8 x 15ft unheated greenhouse are very helpful in hiding the seedlings from the strong winds prevailing in the Chicago area in the Spring.