STRAT AND SCARF Spring is traditionally thought of as the time to start sowing your seeds and this is true for many genus of plants, but so many more prefer and even benefit from autumn or winter sowings. There are many reasons why you’ll have success sowing at this time of year, the main one being stratification. Many seeds are produced with an inbuilt dormancy that prevents the seed from germinating at the wrong time of year where it might be killed by heat or cold. Stratification is a horticultural term used when seed is treated to a cycle of temperature changes, including cold exposure, which mimics the seasons to help break that dormancy. Many of our native wild plants as well as well-known garden perennials require this period of cold and although it may seem counterintuitive at first to sow seeds in autumn or winter and leave them in a cold greenhouse or frame, you will be rewarded in spades come springtime! If you have seed that requires cold stratification, the easiest way I find is to do exactly as described above and be patient and diligent. Some seed takes a notoriously long time until it’s happy enough to go for it, perhaps a whole season! So keep trays weed free and moist for the duration. Another method of seed treatment is called scarification, where a seed requires mechanical or chemical degradation to break dormancy and help germination. This may be due to either very thick seed coatings or chemical germination inhibitors that need to be switched off or washed off. Seeds from the pea family such as lupins or sweet peas often need ‘chipping’, where the hard seed coat is nicked with a knife to allow moisture to access the germ, this would be an example of mechanical scarification. Other seeds may need washing to remove chemical germination inhibitors and some of the coolest seed needs heat and smoke treatment. Many South African and Australian plant seed requires smoke and heat treatment, which mimics their natural scarification by fire, as these plants live in fire dependent habitats. Scientists are still researching the exact specifics that break dormancy in these species, but it’s indicated that volatile compounds within the smoke released from other native plants from the habitat help break-down the germination inhibitor. The natural balance in these regions is incredibly delicate, not only does fire help break dormancy, burn open seed pods to release seed and clear the ground so that seedlings can access light, the act of fire also provides a layer of fresh nutrient and always preceeds the wet season, ensuring the perfect growing conditions for fresh plants. The world of seed sowing is fascinating, particularly the trickier lads! It’s also a very cost effective way to stock your garden with luscious things!
