Knowing when and how to plant seeds is essential for gardeners seeking to save money and grow their own crops.  Some seed-grown crops can be directly sown outdoors, but many must be started indoors for best success. Learning how to correctly plant seed and upgrade and harden off seedlings is vital for indoor seed starting success. Here are a few tips towards getting it all right:

When to Plant Seeds

First know your planting times. This means determining when to plant different crops and what's best planted inside or out. Early spring crops, like lettuce, spinach, cabbage, kale, kohlrabi, arugula, peas and so on, should be planted in late winter or early spring. Some of these, like peas, carrots, and turnips, are best directly sown outdoors in well-prepared garden soil. Others, like lettuce, arugula and spinach, may be sown indoors or out, but indoor seed starting always offers better germination--especially for lettuce, which needs light for germination and tends to get covered with soil during spring rains. The remaining seeds I start indoors, harden off and plant out.

Root crops, like beets, carrots, radishes and turnips, I generally start outdoors in mid-spring. Tomatoes, peppers, eggplant, basil and other warm weather crops are generally started indoors in mid-spring. They don't thrive outdoors until growing temperatures are considerably warm, so I don't actually plant them out until they've reached a good size, it's reasonably warm and there's no threat of frost (usually late spring to early summer).  In late spring, I plant my squash, melons and cucumbers outside. My favorite method is to plant them in pots in a protected place outdoors to ensure good germination and transplant them in the ground when they are around three inches high. Corn must be started outdoors after the first frost date and long-season fall root crops, like rutabagas and parsnips, need to be planted outdoors in early to midsummer.

All cool season crops can be planted again in late summer or early fall for autumn harvest (or winter in southern zones). This is also the time to plant winter crops such as lamb's lettuce or mache.

Indoor Seed Starting, Upgrading and Hardening Seedlings Off

When planting seed indoors, I use good seed starting mix, cover the seeds lightly and keep them evenly moist but not wet. My favorite indoor watering can is a plastic bottle with holes punched in the top. It's a great way to reuse bottles and allows me to water the seeds and seedlings gently.


Smaller seeds, such as these tomato seeds, should be surface sown, lightly covered and kept evenly moist for best germination.


The best small-scale seed/seedling waterer on the planet is also the cheapest.

Good lights are essential for seed starting and the seedlings should only be placed two or three inches from them to keep the plants from stretching towards the light. I use standard shop lights equipped with Sunwave® full spectrum fluorescent bulbs. They're not cheap, but they work. Big box home stores sell cheaper versions that are also good.

I start my seeds in seed pots and upgrade them when they begin to get their true leaves but are still small enough to divide. Those pictured below are the perfect size for upgrading.


Keep seedlings close to the grow lights (2-3"), or they will stretch and become leggy.

To upgrade the seedlings, gently remove them from the pot without disturbing the seedlings themselves. Then slowly tease their roots apart and pluck the seedlings up holding them from their leaves, not stems. Beforehand, I prepare a flat filled with half grow mix and half quality compost and dowel out holes in the center of each pack cell. Then I delicately place the seedlings in, ensuring all their roots are covered before watering.


Purple kohlrabi seedlings waiting to be teased apart, placed in pack cells and watered.


It's essential to hold seedlings by their leaves rather than stems. The delicate stems are easily crushed by fingers.

Once upgraded seedlings have become established and begin to grow nicely, they can be taken outdoors to harden off. This means acclimating them from their cushy, warm grow room to the windy, sunny outdoors where temperatures fluctuate greatly. Indoor grown seedlings are very tender, have weak stems and need time to adjust to full sun. If directly planted outdoors they will fry.

A week is usually long enough to toughen them up. If you have a porch with a sunny spot, it's a great place to begin the hardening off process. As the plants adjust, they can be brought into brighter light.


These mixed seedlings are hardening off on my front porch. They are just about ready to be taken into stronger sun.

One last comment: If you are a gardener in a hurry, heat mats rapidly speed up germination rates of warm season crops.

Outdoor Seed Starting

Starting seeds outside is a simpler affair. Just be sure to establish beds, work up the soil until relatively friable (but not too smooth to avoid a hardpan surface after rain) and plant the seeds in furrows. I cover my seeds with a sprinkling of Pro-Mix, which gives  better germination. Mycorese Pro is especially good because it has beneficial endomycorrhizae to naturally aid plant growth. The key to planting seeds outdoors is making sure they are watered each day if conditions become sunny and rain-free. Overall, the cooler growing conditions of the outdoors result in slower germination rates. If spring temperatures warm up quickly germination will occur sooner, but your seeds/seedlings will need to be watered more frequently.


Good bed preparation will ensure easy outdoor seed starting and great plant growth all season.