|By Skip Richter
Seeds are incredible things! Those tiny dry bits of organic matter cast from the plant seem lifeless and insignificant. Yet seeds are far from lifeless and are the most significant part of a plant. Examine a typical seed packet. The front displays a photo promising beautiful, bountiful results. The back offers instructions to guide us toward achieving this promise. Inside, the contents resemble small pebbles or bits of organic debris. Yet in each one a harvest lays waiting.
You’ve probably heard the old adage, “Man can count the seeds in an apple but only God can count the apples in a seed.” A single seed holds the potential for years of harvests of innumerable flowers and fruit.
I love the winter planting season. Cold, wet weather conditions limit outdoor gardening activities so I head out to the greenhouse to begin my spring garden. Out of the freezer come the various seeds I’ve collected and stored from the past year: a wildflower that looked different in color and plant form than the ones around it, some squash that grew in a mixed planting (who knows what might come of this!), seeds from a friend’s flower garden, and the reseeding lettuce a gardener shared with me a few years back that I still grow each year.
I also have numerous seed packets ordered from various companies, a smorgasbord of vegetables, flowers and herbs. There are always way more than I have space for, but I know you can relate, right?
It’s great winter therapy to plant seeds. Despite the weather outside, seeds promise the arrival of spring, bountiful vegetables and beautiful flowers. Planting seeds is an act of faith and a renewal of the hopes and dreams of any gardener. Seeds look to the future.
Planting a seed sets the stage for a delicious meal or a beautiful bouquet months from now. I recall a shadowbox with small, colorful dried zinnias in it when I was a child. It was a gift from an aunt to my mom years earlier. Looking at those flowers now I can’t help but wonder about the day my aunt held the seeds in her hands. I wonder if she could imagine that years later they’d still be adorning a home.
You can start vegetables, flowers, ornamental grasses, woody ornamentals or even fruit and nut trees from seed if you provide a few simple conditions for their success. The following are a handful of common questions that cover some of the important factors in success with seeds:
What types of plants can and can’t be grown from seed?
Almost any plants can be grown from seed although some types are very difficult, with complex and exacting germination requirements. Some plants seldom produce seed and others fail to produce viable seed.
Many fruit trees are propagated by grafting, budding or from cuttings in order to get a genetic duplicate of the desired variety. If you plant these fruit trees from seed they will end up being similar in some ways to the “mother plants,” but not identical. For proof, take a look at your children or your parents. See what I mean? While such fruit plants can be grown from seed it takes many years for the seedling to reach a mature, bearing age.
Hybrid cultivars won’t produce plants true to the parent plant. If you wish to save seed, choose cultivars that are open pollinated, as opposed to hybrids.
What is the best temperature for starting seeds?
That depends on the type of seed you are planting. As a general guide 70-75 degrees is good for many types of seeds. Some prefer cooler temperatures and others prefer warmer. Some are forgiving of a fairly wide range in temperatures and others are more exacting.
While each species has a minimum and a maximum temperature for germination, each also has an optimum temperature for fastest germination. Tomato seeds, for example, will germinate from a minimum 50°F to a maximum of 95°F, but the optimum temperature is about 80°F. Check the seed packet or an online reference on seed germination to determine the best temperature for the seeds you want to start.
A warming mat beneath seeding trays will provide a fast boost for seeds started in cooler areas such as an unheated greenhouse.
What is the best growing medium?
Most garden seeds germinate best in a loose growing medium composed of equal parts peat moss to hold moisture and either perlite or vermiculite to provide improved aeration and drainage. There are special seed starting mixes available which are finely ground, making it easy to plant small seeds at a consistent depth. Use fresh seed starting mix to avoid some of the common disease problems which can devastate the tender seedlings.
When starting seeds of woody plants I use a mix of 50 percent screened compost and 50 percent soil from the site where the plants will be growing.
How deep do I plant the seed?
As a general rule of thumb, plant a seed at a depth of about 2-3 times its width. That said, some seeds need light to germinate. A few examples include echinacea, ageratum, petunia, coleus, Salvia splendens and nicotiana. These seeds should be scattered on the surface and gently pressed into contact with the growing mix. Check the seed packet for planting depth and whether the seed should be buried or left on or near the surface.
A tip for planting small seeds at a proper depth is to press them onto the soil surface and then sprinkle a very thin layer of fine grade horticultural vermiculite or seed starting mix over the top of them. This makes it easy to barely cover the seeds.
How do I water the seedlings properly?
Start by wetting the seed starting medium prior to planting. If the mix is dry it may initially repel water so moistening before planting is important. After planting, use a mister nozzle to gently wet the planted seeds. Other types of nozzles tend to blast the seeds out of the mix with either strong streams or large droplets.
An alternative is to set the planted trays into a tray of water and allow the moisture to wick up into the mix. Then remove the tray and allow it to drain out all excess water. The idea is to keep the seeds evenly moist, not soggy wet, until they germinate. I like to place the moistened tray into a large clear plastic trash bag or dry cleaner’s bag and fold the end over to hold in moisture.
I put something in the trays to hold the plastic off of the soil surface such as a plant label or a piece of coat hanger bent into a hoop. This creates a moist chamber ideal for germination that generally won’t require rewetting until the seedlings are up. Special seeding trays with clear plastic covers are available at garden centers. They work great! Once seedlings emerge, remove the plastic bag or clear plastic tray cover. Then water as needed to maintain even moisture.
When a seed starts to absorb moisture a complex chemical reaction begins that eventually leads to the emergence of a root and a shoot. Once started, the seed is no longer a tough dry storage container with a dormant embryo, but is a very fragile new emerging life. If the seed dries out even briefly once the germination process begins, it will die. If kept too soggy wet, it will often succumb to root and stem rot diseases.
How much light do seedlings need?
Seedlings require bright light to grow stocky and healthy. Sunlight is best but direct sun is not required. If you can’t give them sunlight, provide very bright fluorescent light. I use two 4-foot shop fixtures each with one cool white and one warm white fluorescent tube. These are suspended over the seedlings and raised 2 to 4 inches above the growing seedlings by chains that allow me to adjust their height as the seedlings grow. A plug-in timer set to run 14 to 16 hours a day provides adequate light for the growing seedlings.
Do I need to fertilize the seedlings?
The germinating seed doesn’t need fertilizing but the growing seedlings do. Once the seedlings get their first true leaf (the “seed leaves” that emerge from the soil first don’t count), begin to fertilize them with a very dilute soluble plant food at the low “constant feed” label rate or a seaweed and fish emulsion solution. Avoid excessive fertilization as this will contribute to the excessive, lanky growth that results in weak transplants.
What about seeds that require special pre-treatments?
Some seeds require cold, moist conditions for a period of time prior to germination. Many of our deciduous landscape ornamentals, fruit trees and shade trees are among these plants. Once again, a good reference book or Web site can tell you which species have such requirements. Place these seeds in moist sand in the refrigerator and leave them there for a couple of months. Then remove the seeds and plant them.
An alternative to this process is to plant them outdoors in the fall and allow winter rains and cold weather to prepare the seeds for germination. Cover the containers with a piece of hardware cloth to prevent marauding squirrels from digging in the pots and spoiling your plans!
Other seeds have hard or impervious seed coats that slow the movement of moisture into the seed to initiate the germination process. Bluebonnets and Texas mountain laurel are examples of seed with hard coats. This is nature’s way of making sure all the seed doesn’t sprout in one season. There are several methods of scarifying these seed coats to weaken them and to speed germination, including nicking with a file, sanding the edges and even using a sulfuric acid solution for a specified period to damage the seed coat.
How do I prepare my seedlings for transplanting?
When it is nearing time to plant the seedlings outdoors, gradually acclimate your seedlings to outdoor conditions. A sudden move from their warm, luxurious life indoors to the garden where nighttime temperatures can still drop into the 40s will shock the plants and slow growth to a standstill. Move them outdoors during the day to a very bright spot in the shade and bring them in at night. Over a period of a week or two, gradually move them into more direct sun and leave them out longer to acclimate them to the cool evening temperatures.
Don’t let the winter weather get you down. Gather some seeds, growing mix and planting trays and head to the greenhouse or make room for planting at an indoor table. Imagine your best garden ever as you start your spring garden indoors. It’s all there in the seeds!