Seed Starting 101

Vegetable and Flower Seed Recommendations for Phoenix Area
January - February
March - April
May - June
July - August
September - October
November - December

Why should you grow plants from seed?
Witnessing a seed sprout and grow into a plant is a joy and wonder of nature!
Starting plants from seed gives you control over growing conditions.

It's less expensive than purchasing plants, especially if you want large numbers.
Many unique or larger varieties are not available in garden centers as plants.
All Botanical Interests seed varieties have been pre-tested for germination rate at an independent laboratory to give you the best chance for success.


What do seeds need to succeed?
A Comfy Container - Almost any empty container at home can be used to start seeds - clean milk, yogurt, or margarine containers, egg cartons, etc. Seed starting trays and small packs are also available at garden centers and are fairly inexpensive. Any container used must have drainage holes on the bottom. If you reuse containers each season, be sure to disinfect them with a 1:9 bleach solution to destroy any potential seedling pathogens.
Good soil - For best results, always start your seeds in a high quality seed starting mix (available at most garden centers and nurseries). It will be light and fluffy to prevent compaction and will not have pathogens or pests like garden soil.
Consistent moisture - Seedlings must be kept moist (but not soggy) at all times. If they dry out just once, they are "toast"! Conversely, you don't want to drown them. Soil that is too saturated is an invitation for fungal problems.
Air Circulation - Indoors, providing good air circulation (similar to wind fluctuations outside) will help prevent damping off fungus (causes stems to get spindly and fall over) and increase the strength of each seedling's stem. To do this, you can place a small oscillating fan a few feet away from seedlings.
Temperature - Most seeds will germinate just fine at room temperature.
A heat mat is usually not necessary, but seeds that prefer very warm temperatures for germination (like tomatoes and peppers) may benefit from it.
And most importantly ... Let there be light!
When you start seeds indoors, do they get tall and skinny and fall over? The most common reason that seeds don't develop into healthy plants is lack of sufficient light. If you are starting them indoors, they must be in a sunny south-facing window that gets light most of the day or be under fluorescent light bulbs with 14 to 16 hours of light every day. (You should keep the lights 1-2 inches above the seedlings to prevent them from stretching towards it.)
When to Plant:
Before you plant, the most important thing to know is when the
AVERAGE LAST FROST DATE occurs in your region in spring. (If you are interested in planting a fall garden, look up your AVERAGE FIRST FROST DATE.) You can contact your local county extension office for this information and more particulars about gardening in your area. To find your local office, click here: Local Extension Office 
For a general U.S. map of average last frost dates, click here:
Average Last Frost Date
Why is this important? So you will know how many weeks before the last frost to start seeds indoors or when it is safe to plant or transplant outdoors.
Sowing indoors: What types of plants should be started indoors?
Plants that require a long growing season to reach maturity
Biennial or perennial flowers that you want to encourage to bloom in first season
Plants grown for edible sprouts
Some vegetables that are recommended for starting indoors include:
Artichokes, celery, eggplant, endive, leeks, onions (bulbing), peppers, sprouts (alfalfa), sprouts (mung bean), sprouts (fenugreek), tomatillos, tomatoes, wheatgrass
Herbs that are recommended for starting indoors include:
Most herbs, but especially: fenugreek (for sprouts), marjoram, oregano, savory, thyme
Some flowers that are recommended for starting indoors include:
Flax, Impatiens, Lobelia, Marigolds, Nemesia, Ornamental Peppers, Ornamental Eggplant, Pansies (12 weeks before blooms desired), Salvia Blue Victoria, Statice, Violas
(Also note that seedlings started indoors must be 'hardened off' gradually to allow them to adjust to outdoor weather conditions. Put them outside in a filtered sun/shade location away from harsh winds during the day for just a short time at first. Bring them in at night and gradually increase their time outdoors each day for a week.)
Sowing outdoors: What types of plants should be started outdoors?
Plants that don't transplant well (weakened by root disturbance)
Plants that require very warm temperatures to sprout and get established
Root crops (carrots, beets, parsnips, etc.)
Vegetables that are recommended for starting outdoors include:
Amaranth, arugula, beans, beets, bok choy, broccoli, carrots, cauliflower, corn, edamame, gourds, mustard, onion (bunching), parsnips, peas, pumpkins, radishes, spinach, squash (summer), squash (winter), Swiss chard, turnips
Herbs that are recommended for starting outdoors include:
Borage, cilantro, Clary sage, dill, fenugreek, mitsuba
Flowers that are recommended for starting outdoors include:
All large packet flower mixes, Baby's Breath, Bachelor Button, Bishop's Flower, Black Eyed Susan Vine, Broom Corn, Cardinal Climber Vine, Castor Bean, Cat Grass, Chocolate Flower, Cleome, California poppies, Forget-Me-Not Spring & Summer, Four O'Clock, Godetia, Hyacinth Bean Vine, Love in a Mist, Money Plant, Nasturtiums, Poppies, Sunflowers, Virginian Stock, Zinnias
Most Botanical Interest varieties not listed above can be started indoors or outdoors. Follow instructions on back or inside of packet.
So now that you've taken Seed Starting 101, it's not too early to start choosing seed varieties for your spring garden if you haven't already.
Remember that some plants like TOMATOES and PEPPERS require sowing indoors 6 to 8 weeks before transplanting outside, and you will want to give them a good head start before spring to get the most fruit before fall frost.


Michelle DePaepe, Botanical Interests, Inc.