How to Grow Perennials from Seed
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.
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
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.
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.
Label the container.
Write the name of the plant, the date you planted it, and any other information that you think may be useful.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.