How to do your own seed harvest in Sonoma County

There is no doubt about it ­- summer is here and our winter and spring-planted winter annual flowers are concluding their bloom season. It’s time to think about saving seeds from those you like.

Annual plants generally don’t live for even one year. They live only one season: winter or summer. Those adapted to cool or cold weather are referred to as winter annuals or hardy annuals and are planted in very late summer to fall or in early spring when temperatures are cooling off and soil is moist. These plants bloom in winter to early summer depending on the plant species.

Each plant species has a specific bloom time. For instance, violas and pansies are some of the earliest and longest blooming cool season annuals - often flowering from January through May following a September or October planting. Others like Shirley poppies flower in April and May from a fall planting, finishing bloom in early June as temperatures warm.

Many of the cool season annuals are not heat tolerant. All need regular water. Heat stimulates them to conclude their bloom season and set seed. Other familiar winter and spring blooming plants are flowers like cerinthe, Iceland poppies, love-in a mist (nigella), larkspur, flax, breadseed or hybrid poppies and sweet peas. Many of our native wildflowers are in this category also and bloom in succession from February through May and June depending on the species. These winter annual flowers are invaluable for color in the winter and spring months when not much else is blooming. Along with spring bulbs, they usher in the new growing season each year with a variety of gorgeous and uplifting blooms.

It is hard to say goodbye to some of the sumptuous annual flowers. The best way to perpetuate their beauty is to save seed from the plants you enjoy the most. Two years ago I planted a hybrid breadseed poppy called Papaver hybridum ‘Lavender Feathers.’ The plants are very upright and about 3 feet tall, with distinctive broad gray leaves with fringed edges. The huge lilac blooms are double, and the petals ruffled and fringed. Each forms an incredible picture. I let the seed pods dry and scattered the seed in my vegetable garden.

This year, I am enjoying a feast of these flowers. In another garden we have been saving seed each year from a bright pink version of the same type of poppy to perpetuate its glory. A few other special annuals worthy of seed-saving are the double, deep-burgundy Shirley poppy, a dark navy blue love-in-a-mist (Nigella) and a low growing Phacelia - Phacelia ciliata. You may have a special flower such as these, or enjoy a mixture of colors. Either way, now is the time to identify what plants you like and want to perpetuate before the blooms fade completely.

Ways to go about this vary, but I like to tie flagging tape on the plants, written with the name or a brief description of the flower I want to save. You can also put in a flag or name tag. Note that if you have a mixture of flower colors, and bees are visiting them, you will end up with a mixture of colors - not just the flower type you want to keep. If you can isolate a special variety, it will help ensure the purity of the flower characteristics. Otherwise, you will have only a percentage of the flower type you desire from seed you collect.

As the plants finally decline and their seed matures, many develop yellowed leaves and do not look so good. You can pull most of them out, as one or two plants usually produce many seeds, and quite enough for a home garden. Having a few scraggly plants for a short time is a small, brief price to pay for perpetuating varieties you like, and to share with friends or neighbors.

As with any plant you are saving seed of, wait until the seedpods are completely dry before harvesting seed. There is a crucial point when the seedpods are dry and seed is ready - before the seeds fall from the flower.

You will need to watch closely, but don’t be tempted to collect seed when buds are still green. An easy way to collect seed from larger plants is to put a large paper bag over the plant as far down as it will go. Then bend the plant and bag over so the seed falls down into the bag. Shake the plant to cause seeds to fall out of the pods. You can often hear them falling into the bag. Cut the base of the plant with pruning shears instead of pulling it from the ground to avoid getting soil in the bag. After most seeds fall, discard the plant.

With smaller plants, use a smaller bag or an envelope. The seeds should be allowed to air dry in a cool, dry place for two to three weeks. Then place seeds in double Ziploc bags, well-sealed, or an air tight jar. Store them in the refrigerator or in a cool place until fall or very early spring. Leaving seeds in paper bags causes them to dry too much, and seed viability will fall.

A very easy way to perpetuate plants you like is to simply cut off the plant at the base when the seed pods are dry and shake the plant around the garden where you want the plants to grow. You will get from zero to many plants from this method depending on conditions in your garden. I use this method with columbine and our native wildflowers. Columbine is a perennial, but seed is ready now and is very easy to collect. I get a few new plants each year from this way of seeding.

Seedlings of winter annuals generally do not germinate, and grow until fall when cool soil temperatures and moist conditions stimulate seed to sprout.

With any plant, there are some varieties that may have a higher seedling rate of survival than you would like. Each garden has different conditions, so it is hard to predict what plant might end up being too vigorous. If too many seedlings survive, pull out some plants before seed sets.

Kate Frey’s column appears every other week in Sonoma Home. Contact Kate at: katebfrey@gmail.com, freygardens.com, Twitter @katebfrey, Instagram @americangardenschool