San Francisco Chronicle - (Sunday)
Let your garden grow from seeds
With spring around the corner, it’s time to get a head start on flowers and greens
It may not be spring yet but now is a good time to consider starting vegetables or flowers from seed.
Why grow plants from seed? One seed packet contains anywhere from 10 to 100 seeds, allowing you to grow a large quantity of plants. Second, the volume of seeds means that you can stagger the propagation sowings. That’s useful for vegetables and especially leafy greens like lettuce and kale. Lastly, there are many more varieties of plants available in seed form, rather than live plants, either at garden centers or online.
Apart from those practical considerations, it is very rewarding to grow plants from seed, from watching the first sprouts appear all the way to seeing your flowers flourish or your homegrown vegetables ready to harvest.
Indoors or outdoors?
Choosing the plants you will grow from seed is perhaps the most fun of all. There are several things to consider: Will you be starting the seeds indoors or out? You can start many seeds indoors a month earlier than starting them outdoors. For instance, you can start frost tender plants indoors in midFebruary but would need to wait until midMarch to start directly outdoors. Each seed packet should have sections on the back that will tell you when to sow outdoors and when to start indoors. Follow those guidelines.
Best spring flower and vegetable seeds
Flower seeds are divided into three groupings: First is the single variety packets — say, Calendula Oktoberfest — where there is just one variety of seed; second is one genus but a variety mix, be that different colors or sizes (for example, LoveinaMist Persian Jewels mix). Lastly, are the popular wildflower mixes. There are a host of these: for pollinators; a fairy garden; cottage garden flowers; or all California natives. These mixes typically contain 1530 different plants. The one unifying factor is their look or purpose.
Popular flowers to start in early spring include sweet peas, LoveinaMist, breadseed poppies, linaria, cosmos and zinnias.
Choosing vegetable seeds is a bit easier as most will be a single variety. Popular selections for early spring include tomatoes, peas and early squash as well as the leafy vegetables that most of us in the Bay Area can grow yearround (lettuce, spinach, kale, Swiss chard). Again, the sowing information on the seed packet will be your guide for when to start a particular seed.
Starting seeds indoors
The setup is pretty basic: a seed tray, seed starter mix, some window space and regular watering. Seed trays measuring 20 inches long and 10 inches wide come either as an open tray or with individualized cells, usually 72 cells per tray. The advantage of the latter is that the partitions separate the new sprouts, making them easier to transfer later. The cells also make it easier to mark these separately if you’re sowing multiple varieties of seed in one tray. Note that the open trays do not have drain holes, while the partitioned trays do and so come with a bottom drain tray. This is important when it comes to watering.
Seed starter mix, sold at most nurseries, is recommended for flowers, as it is a light, sterile mix meant for seeds. I’ve found that Edna’s Best potting soil works equally well for starting vegetables and is also available in smaller bags.
Fill the tray with the soil, leaving a halfinch at the top. Following the seed packet instructions for seed depth and spacing, press the seeds, usually 35, into the soil. Using a watering can with a “rose” head for gentle and even watering, soak the soil lightly, being careful not to leave any standing water. Allow the soil to dry between waterings but don’t let it stay dry too long. That might mean watering as often as every day. In a cooler home, you might use a heating mat. Think of them as an electric blanket that goes underneath the tray to keep it warmer. This may improve germination rate and the overall viability of the seedlings. (Note: In an open tray, the mat will go under the tray; in a tray with drainage holes, the mat will go underneath the drain tray.)
As seeds germinate (see seed packet for Days to Emerge), continue with regular watering. Refer to the packets for whether these sprouts will need thinning out. This thinning will be needed in some cases if there are too many sprouts too close together, resulting in too much competition for nutrients.
There is no hard and fast rule for when to transfer shoots, but a transition container is advised as shoots will outgrow the shallow soil in the starter tray but not always be mature enough to be planted outside. A good guideline is when the plants reach a height of 34 inches, transfer them to individual containers or to the outside. When you pull the shoot out, you should see the beginning of a root system. When transferring the shoot to a pot, make sure to use a light soil mix with good drainage. Soil that is constantly wet will damage young roots. This new container might be its final home or it might be a transition before the plant is situated in an outdoor bed. Assuming the last frost has passed, it is recommended to move these transition pots outdoors. This will help to “harden off ” the plants for their life outdoors. I recommend putting these containers in bright shade for the first week, then halfday sun for the next week and finally into full sun (assuming this is a plant that wants full sun). Plants can be planted out after the first two weeks of being outdoors.
Sowing plants outdoors
Sowing seeds directly outside can be a lot easier than starting them inside, but it does bring into play the elements of the weather. Check seed packets for when to sow any particular seed outdoors. Broadly speaking, there are two ways to sow seeds outside: Start them in containers or broadcast seeds directly in planting beds. You can follow the same steps as for indoor germination if starting seeds in outdoor pots. Obviously, you won’t need a hardeningoff period.
When sowing directly in beds, make sure the soil is loose and fertile. Hardpacked soil makes it hard for roots to develop, and soil of poor quality will stunt the seedlings’ growth. Clear any debris from the soil area and pour the seed into your palm. Then, evenly broadcast the seeds in the bed. Cover with ¼inch soil and water lightly. Although you can broadcast directly with any type of seed, this method is most common with the seed mixtures mentioned earlier.
One warning: When these seeds begin to germinate, don’t forget what they are and accidentally weed them out. Also, if you have dogs or other rambunctious creatures visiting your yard, you might consider securing netting over this ground, at least until the young plants are established. And if you enjoy a high germination rate, you will no doubt need to thin out the mass of new plants.
Inside or out, flower or vegetable, it is very rewarding to grow your own plants from seed!
The setup is pretty basic: a seed tray, seed starter mix, some window space and regular watering.