by Leslie Cox; Wednesday, September 20, 2012

As summer nears its end, it is a good time to be thinking of gathering seeds for the next growing season.

Timing is everything when it comes to harvesting seeds. Collect them too soon and the endosperm may not be fully developed enough to supply the necessary nourishment to the embryo for it to finish maturing. Collect the seeds too late and there is a risk that they may have begun to rot or have lost their viability. Usually, seed maturity can be measured by colour—lightness of colour means it is not mature; darker means mature.

Flower seeds are ready for collecting a few weeks after the flowers have faded and the petals have dropped off. Plants with flower spikes where the blossoms open at the bottom first and slowly work up to the top, or vice versa, are harder to judge the optimum harvest time. The seeds, like the blossoms, ripen at timed increments.

Annuals are good seeds for the beginner. Most are fairly forgiving if your timing is a bit off, achieving viability even after collection. Perennials produce seed every year, but only seeds from fully mature plants are viable. Biennials will only produce viable seeds for collecting in their second year.

Fruits and vegetables should be left on the plant for a week or two beyond when they would have been harvested for eating. This allows time for the seeds to finish maturing.

Paper bags work well for collecting flower seeds as they allow good air flow for drying. Simply snip the flower stalk and carefully invert the seed head upside down into the bag. In most cases, the seeds simply fall to the bottom of the bag when dry and can then be easily transferred into a suitable container for storage.

Make sure your seeds are clean of any debris before storing. Plant debris could be harbouring insects or fungi that could potentially destroy your seeds. Any debris left on the seeds can also attract moisture which will speed up the seed’s metabolism to begin germinating when it should be in its dormant stage. This is especially true for seeds from tomatoes, squashes, melons, etc.

An easy way to collect tomato seeds is to squeeze the pulp and seeds into a container filled with water. Give the solution a brisk stir and allow to sit at room temperature for 2 or 3 days. The pulp and non-viable seeds will float to the top while the viable seeds will sink to the bottom. Skim off the floating material before draining the remaining seeds through a coffee filter. Allow to dry thoroughly before storing.

Proper seed storage is arguably the single most important part of the seed saving process. Handled correctly, the seeds will hold their viability over to the next growing season. Depending on the species, some seeds will remain viable for a few years provided they are stored under proper conditions.

A good example is the malva seed that was discovered embedded in the wall of an adobe house. Estimated to be approximately 200 years old, it germinated when planted!

Temperature and moisture are two important factors that must be considered when storing seeds. They must be kept consistently cool to hold them in a dormant state until it is time to plant again. The refrigerator is the best place to keep seeds because it maintains a constant temperature. An unheated garage or basement is also suitable providing the temperature remains fairly cool and does not fluctuate too much. Wide swings in temperature are fatal to good seed viability. Seeds can also be stored in the freezer. The colder seeds are kept, the longer they remain viable. However, they must be fully ripe and kept very dry if you are going to store them in the freezer.

Last but not least – be sure to label the type of seed and date collected. Spring is a few months away.