How to Grow Perennials from Seed
By The National Gardening Association, Bob Beckstrom, Karan Davis Cutler, Kathleen Fisher, Phillip Giroux, Judy Glattstein, Mike MacCaskey, Bill Marken, Charlie Nardozzi, Sally Roth, Marcia Tatroe, Lance Walheim, and Ann Whitman from Gardening All-in-One For Dummies
Growing perennials from seed gives you the chance to start literally hundreds of plants from one package of seeds. Most perennial seeds don’t germinate very successfully when planted outside. By starting the seeds indoors, you can create an artificial environment to meet their needs.
You can grow perennials indoors any time of the year. But if you start them in late winter or early spring, the seedlings are usually large enough to go into the garden by early summer. For best results, plant seeds outside at the time of year recommended on the seed packet. Some seeds need cool weather to sprout, and some need hot.
1
Fill your containers with potting mix to within 1⁄2 inch (1 cm) of the top; pat the mix down lightly to press out air pockets.
The mixture is wet enough if you can form a handful of it into a ball, but too wet if it drips. Suitable containers are anything potting soil and seed can fit into. Run your containers through the dishwasher or wash them in a weak solution of household chlorine bleach. Poke holes in the bottom and sides so that excess water can drain away
2
Using your forefinger and thumb, sprinkle the seeds over the surface of the potting mix.
As a general rule, use twice the number of seeds as the number of plants you hope to grow.
3
Cover the seeds with dry potting mix according to the packet instructions, and then lightly spray mist the surface with water.
You don’t need to cover seeds smaller than grains of table salt; instead, use your fingertips to lightly press them into the soil.
Write the name of the plant, the date you planted it, and any other information that you think may be useful.
5
Cover the container with a lid, plastic wrap, or glass.
If the instructions tell you to exclude light, cover the container with aluminum foil instead of plastic wrap or glass.
6
Place the seed containers on trays and set them on the stand under grow lights.
For those seeds that require heat, you can buy special heating cables to keep the trays warm if your location isn’t warm enough.
7
Open the container and check the seeds every day.
If the potting soil starts to dry out, wet it with a couple of squirts from your misting spray bottle.
8
When you see little green specks emerging from the soil, remove the lid and lower the grow light until it’s positioned a couple of inches above the seedlings.
Raise the light as your plants grow taller.
9
Continue to water with the misting spray bottle until your seedlings start to form real leaves; then water from the bottom by placing the container in a sink filled with a couple of inches of lukewarm water.
The first pair of leaves that appear are seed leaves, not true leaves. Seed leaves feed the young plant until it can grow the real thing. When your seedlings grow four true leaves, transplant them to larger, individual containers.
10
To transplant the seedlings, fill the new pots with damp potting mix and use a pencil to make a hole in the potting mix in each pot.
The hole should be deep enough to accommodate the seedling's root system.
11
Dump the seedling container gently onto your fingertips and then place the seeding clump upright on a tray.
Recycled 2-1/4-inch (6 cm) and 4-inch (10 cm) nursery pots are handy for this purpose.
12
Pull a seedling away from the clump, holding it by a leaf, and use a pencil to guide the roots into the hole you made in the potting soil.
Press the potting mix gently around the roots, so that the stem is at the same level it was in the seedling pot.
13
Water the plant with a weak solution of liquid fertilizer (mixed at about a tenth of the normal label recommendation for perennials).
Fertilize once a week, gradually increasing the strength to the rate on the label for seedlings.
14
Water from the bottom until the seedlings double in size; after that, you can use a watering can.
Grow newly transplanted seedlings under grow lights or in a brightly lit location out of direct sunlight. When the plants are several inches tall, harden them off and plant them in the garden.
You can also grow perennials outside by following the preceding steps. But instead of placing your pots on a light stand, put the pots outside where they can remain undisturbed until they germinate. You can build a frame or a low box to house the pots. Some perennials may take years to germinate, so don’t give up on them too hastily.
Gardening Glossary
annuals
Plants that complete their entire life cycle within one growing season. The plant germinates from seed, grows and blooms, and then produces seed and dies.
Gardening Glossary
biennials
A plant that take two growing seasons to complete its life cycle. It germinates and grows leaves and stems in the first year; produces flowers and fruit (seed) in the second, and then dies.
Gardening Glossary
bolt
When a plant flowers or produces seed prematurely.
Gardening Glossary
cold frame
A wooden or concrete block box in which you can grow plants or hold dormant during the cold winter months.
Gardening Glossary
cole crops
A family of vegetables, including broccoli, cabbage, cauliflower, kale, and Brussels sprouts. They thrive in cooler weather.
Gardening Glossary
complete fertilizer
Any fertilizer that contains all three of the primary nutrients, N-P-K (nitrogen, phosphorus, potassium). Phrase is based on regulations governing the fertilizer industry. Does not mean that the fertilizer literally contains everything a plant needs to thrive.
Gardening Glossary
deadheading
The practice of pinching or cutting off spent flowers
Gardening Glossary
evaporative-pad humidifier
A humidifier in which fans blow across a moisture-laden pad that sits in a reservoir of water.
Gardening Glossary
harden off
The process of acclimating plants grown indoors gradually to the brighter light and cooler temperatures of the outside world.
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hardiness
The ability of a plant to survive is called its hardiness.
Gardening Glossary
humus
A stable end product of organic-matter decomposition that's believed to increase microbial activity in soil, improve soil structure, and enhance the root development of plants.
Gardening Glossary
Bacillus thuringiensis Bt
An effective bacteria that attacks only the larvae of caterpillar family insects. It is safe to other insects, animals, and humans.
Gardening Glossary
macronutrients
Mineral nutrients that plants need in the largest quantities: nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur.
Gardening Glossary
mulch
Organic or inorganic material placed over the surface of soil, usually directly over the root zone of growing plants. Used to conserve moisture, kill weed seedlings, modify soil temperature, provide attractive covering to garden beds.
Gardening Glossary
organic matter
Once-living stuff like compost, sawdust, animal manure, ground bark, grass clippings, and leaf mold (composted tree leaves). Used to enrich soil and improve soil texture.
Gardening Glossary
perennials
Any plant with a life cycle of three or more years. Herbaceous (non-woody) perennials include flowering plants and herbs, mainly. Woody perennials include trees and shrubs. Longevity depends on the plant and growing conditions.
Gardening Glossary
pH
The measure of soil's acidity. Soil with low pH means it's too acidic; soil with high pH means it's alkaline. Most plants grow best in soil with a pH value between 6.5 and 7.2. Neutral soils measure 7.
Gardening Glossary
photosynthesis
The process through which plants take nutrients from the air and from the water in the soil to produce sugars that fuels the plant's growth.
Gardening Glossary
primary nutrients
Nitrogen, phosphorous, and potassium are the three nutrients plants need in the largest quantities.
Gardening Glossary
root crops
Plants with edible underground roots such as onions, carrots, beets, potatoes, turnips. Most root crops are cold-weather crops.
Gardening Glossary
self-blanching
A type of cauliflower with leaves that naturally curl over the head and exclude light. Requires cool temperatures for leaves to curl effectively.
Gardening Glossary
sets
Small onion bulbs, about 1/2-inch wide, that were started from seed the previous year. Grow onion sets with the pointy end up.
Gardening Glossary
side-dressing
The act of adding a small amount of fertilizer around or "on the side" of plants after they're growing.
Gardening Glossary
succession planting
Planting small, 2-to-4-foot patches of plants every two weeks throughout the growing season so that you can harvest a crop over an extended period of time.
Gardening Glossary
thinning
The act of cutting the least robust seedlings in your garden to give the healthier plants more room to grow.
Gardening Glossary
vining crops
Crops that grow on vines, such as cucumbers, melons, pumpkins, and winter squash. They usually require support (staking, trellising, etc.) to keep them off the ground.
