If you are planning on propagating a plant from seed, consider where the seed comes from. Species and heirloom varieties will produce seeds from which the same or a very similar plant will grow. Cultivars will not. If you are looking to propagate a special variety, such as a variegated specimen, vegetative propagation is the way to go.
Collect the seeds when they are mature. If you harvest the seeds from the mother plant before they are ready, the seeds may not grow. If the plant bears fruit, this is usually when the fruit has ripened. Plants that form capsules may need to turn brown and some plantsí seeds are ripe when they fall off the plant entirely. To catch seeds that may be ejected from the parent plant, tie cheesecloth on the fertilized flower. The seeds will be neatly contained instead of scattered about the room.
Some seeds need to receive special treatment in order to germinate. Scarification, stratification, and the aging and drying of seeds may be necessary in different combinations. Scarification is scratching the surface of a seed physically or chemically (i.e. dissolving the hard shell) to allow moisture to penetrate. Stratification is only seen in plants that grow in temperate regions; it is a cold period that the seed must be exposed to for a certain length of time before it will germinate. Other plants that come from a region with a dry season may need the seeds to be dried before they will germinate. It is important to be aware of these treatments that a seed may need in order to germinate. If you have had bad luck getting a plant to grow from seeds you purchased, a pre-treatment may be what is lacking.
Selection of media is important. Youíll want one that is sterile to promote the healthiest seedlings. There are commercially available seed-starting mixes on the market, but you can also blend your own. Peat moss, vermiculite, perlite, grit, or horticultural-grade sand are all excellent ingredients for propagation media. Experience and knowledge of the media and seeds are helpful when preparing your own recipe; if you are not sure what will work best for your situation, stick with the pre-mixed.
Pre-germination is the soaking of seeds in water for a day or two before planting in order to hasten growth. It can be helpful when you are not sure whether the seeds you are trying to plant are viable; you can visibly see the seed sprouting before you even plant it. It is important that the radicle (the emerging root) is not broken when you plant the seed. If the radicle is broken, the seed will die.
Some seeds need light to germinate. Find out before planting whether to sow the seeds on the surface of the mix or to lightly cover them. If you bury seeds that need light to germinate, they will never grow.
Humidity is important to delicate, newly emerged seedlings. It can be provided with a plastic cover or plastic wrap held away from the seedlings with stakes or toothpicks. It is better to use a cover of some sort than to mist as water on the leaves invite disease.
Providing heat from below often results in more rapid germination; heating pads for this specific purpose are sold online and in hydroponics shops. Bottom-heating is credited for not only more rapid germination, but for higher rates of germination. If the seeds you are sowing are expensive, hard to acquire or otherwise special to you, it may be wise to invest in a good seedling starter mat.
Every plantís seed has its own unique set of requirements for germination. Hopefully, you will have greater success propagating from seed with the information herein. Good luck and happy sowing!