Successfully germinating seeds
It's planting time! We want you to be successful when starting your seeds. Here are a few tips to remember when you get to growing your seeds:
The basics of seed germination:
Healthy seeds are little protected packets of everything a plant needs to get off to a great start. As a survival mechanism, seeds are dormant and protected by a hard seed coat until the right conditions arrive for them to grow. They've evolved this as a protection, otherwise they would germinate in unfavorable conditions. When we germinate the seeds for our garden, we strive to create just the right conditions for that species to germinate best.
Soil is the perfect germinating medium for a few different reasons. Soil keeps the seed moist. Soil keeps seeds dark, and most vegetable seeds like this. In the case of some species, soil also provides chemicals needed for germination. Tomatoes, for example, germinate best in the presence of phosphates from soil.
Planting seeds too deep can delay germination and shoot emergence. Deeper soil is cooler and may not warm up enough for germination to occur. Planting seeds too shallow will cause them dry out. Follow the recommendations on the seed packet, and as a general rule of thumb, don't plant deeper than 2X the length of the seed itself.
Seeds need moisture to germinate. Though some drying out is usually tolerated, the more consistent the moisture the better. Because seeds also need oxygen to germinate, standing water or over-watering will harm germination rates. To prevent this, plant seeds in well drained soil.
When pre-soaking seeds prior to planting, as is often recommended to hasten germination for very hard shelled seeds such as peas, beans, okra, and corn, keep in mind that 12-24 hours is usually best, and any longer the seed can be harmed from lack of oxygen.
Ideal Germination Temperature:
In addition to moisture, temperature is perhaps the most important factor to consider. While many seeds will do just fine in the room temperature range of 65-75, some have very specific preferences. Some, for example, need cooler nighttime temperatures. For our seeds, refer to the packets as we publish ideal germ temps for all our varieties. For a great general vegetable germination temperature table, check out this one published by the University of California Extension Service.
Light or Dark?
Most vegetable seeds require some darkness to germinate, but some seeds like lettuce, celery, and celeriac, require dappled light in order to germinate. Lightly press these seeds into the soil, or cover very lightly.
Keeping seeds moist in the heat of the summer:
**Some seeds require special treatments to break dormancy and begin germination:
For most of our vegetable and common flower seeds, the right temperature and moisture requirements will cause the seeds to germinate. Over time, germination inhibitors have been bred out of the DNA simply by gardener and farmer plant breeders selecting the plants that would germinate without those seed treatments.
Most native plants, as well as some flowers and herbs, still have germination inhibiting mechanisms at play. These include cold stratification and seed coat scarification.
Cold Stratification is clever way seeds evolved to not germinate too soon in warm fall days right before winter. Seeds requiring cold stratification require a period in a moist, cold environment, before they will germinate. This tells the seed it has gone through the winter (or winter-like artificial environment) and it is safe to start growing. The period of time varies, but often around 4-5 weeks at around 40 F will work.
Cold stratification requirements can be met a number of ways. Often the easiest way is to simply plant the seeds outside in fall and allow the real winter to do the work. Seed then emerge when they are ready in spring. Another way is to place seeds in a moist paper towel in a plastic bag in the refrigerator for 4-5 weeks. Then, take the seeds out and plant them in their ideal growing conditions.
Seed Scarification involves a slight breaking of the hard protective seed coat to initiate germination. In nature, this can be accomplished with fire or by passing through an animals stomach and being exposed to stomach acids. We can accomplish this by nicking the seed coat with sandpaper or a file. Fine sandpaper is best for small seeds. Nicking the seed coat enough so the under color comes through in at least one place should be enough. For large seeds like okra we use the file. We file the seed coat down in one spot until we see the undercoat beneath.
Seed scarification can be a fun learning experience for teaching about what happens to seeds to help them begin growing in nature. Marshmallow and Okra are two seeds we carry that benefit from some amount of scarification.