When Should I Fertilize Seedlings?

“I bought Black Gold potting soil with fertilizer for my herb, tomato, onion, and pepper seedlings. Do I also need to use liquid fertilizer once the seedlings grow their true leaves?” Question from Kim of Hiram, Ohio

Answer: It is important to be timely when fertilizing seedlings to give them the best head start. With that said, fertilizer in the soil can actually inhibit the germination of some seeds. (The salts in fertilizers disable the uptake of water in some seeds, which reduces or stops germination.) So, we recommend starting seeds in a mix that does not contain added fertilizer. Black Gold Seedling Mix is perfect for all types of seeds, and Black Gold Natural & Organic Potting Mix is a little coarser and great for starting larger seeds, like sunflowers, squash, and beans.

From there, start feeding seedlings with a 1/2 dilution of water-soluble fertilizer formulated for vegetables after they have begun to develop their true leaves. As they become larger, you can graduate to a full-strength dilution. I recommend waiting until they are 4-5 inches before feeding them fully.

I hope that this helps!

Happy gardening,

Jessie Keith

Black Gold Horticulturist

How Do I Start Seeds?

“Hi, I have the worst time starting seeds and am not sure what I’m doing wrong. Do I need to put a heating pad under the tray and a light on top? If so, can I use a regular heating pad for under them? Can I use a regular shop light above them? I cover them with plastic wrap until the seeds sprout, which hasn’t been happening, and then it gets all moldy. I just tried a tray of rock wool with 50 seeds! All I’ve got so far is mold, no sprouts. Every year I end up giving up and buying plants from the garden center. I have a lot of seeds, I collect and trade and I’d like to be able to successfully start and grow them. Thanks for your help.” Question from Lucia of Huntington Beach, California

Answer: Seed starting takes patience. The most common mistakes that gardeners make are that they plant the seeds too deeply, they overwater them, or both. Too little water is another common problem, especially when they are just beginning to sprout. A little dry soil can mean instant death to a tiny seedling. Here are my recommendations for each of your questions followed by some excellent seed-starting resources we have.

  1. Do I need to put a heating pad under the tray and a light on top? Yes, to both, though not all seedlings require bottom heat. It is best reserved for warm-season vegetables and flowers, such as tomatoes, peppers, marigolds, cleome, and salvias.
  2. Can I use a regular heating pad under them? No, regular heating pads cannot be wetted and may short out and start a fire. Seedling heat mats are not too expensive, they are safe, and just the right size for a seedling flat. (Click here to learn more.)
  3. Can I use a regular shop light above them? There are lots of lighting options, with shop-light fixtures being the most economical. Some shop-light fluorescent bulbs are specially designed for plant growth and cover more of the spectrum–up to 94%. These are the bulbs to use. In general, fluorescent bulbs are not very strong, so they must be placed just inches above seedling flats or plants for best light reception and growth.
  4. I cover them with plastic wrap until the seeds sprout, which hasn’t been happening, and then it gets all moldy. Your soil and seeds are too wet, so the whole lot is rotting before any growth can happen. Wash your pots well before you try planting again to remove any mold spores. Then fill the pots with fresh, moistened Black Gold Seedling Mix, sprinkle the seeds on top, add a light sprinkling of the mix over the seeds, and then keeping the tops lightly misted daily. (Click here to see a nice plant mister.) The soil should be kept lightly moist, never wet. For larger seeds, plant them 1 to .5 inches down, no deeper. Most seed packets recommend that you plant seeds too deeply.

From there, try reading a couple of these great articles about seed starting. We also have a video about starting tomato seeds below.

Seed Starting Article Links




Happy gardening!

Jessie Keith

Black Gold Horticulturist

10 Tips for Seed Starting on a Budget

Reused plastic cups make good seedling pots as long as you poke holes in the bottom.

Are you low on cash but want a summer garden? No worries. Seed starting can be very inexpensive if you know where to shop, when to plant, and how to succeed with as few resources as possible. Fancy seed-starting flats are not needed, reuse instead. Pricy grow lights can be bypassed if you have sunny window sills. Some quality seed vendors are more reasonably priced than others. Here are these and more tricks for seed-starting on a budget.

(If you are new to seed starting, I recommend you read our six-part seed starting blog series.)

1. Buy Seeds for Less

Some seed vendors have great prices and great seeds!

Some seed vendors sell high-quality seeds for less–for me “less” means between $1.50 and $2.50 per packet. My all-around favorite seed vendor for quality and price is Pinetree Garden Seeds. I’ve purchased from them for over 20 years, and their prices, selection, and seed quality are always outstanding.  Another great, reasonable seed source is Botanical Interests (their flower seed collection is especially nice).

Other seed sellers offer lots of seeds for less. High quantity is especially useful for gardeners that grow lots of row crops, like carrots, beets, and beans. Franchi Sementi (also called Seeds of Italy) is one the best for low-cost bulk seeds. (They also have fun European vegetable varieties.) Packets may cost $4.50 each, but most contain hundreds of seeds per packet! It’s a super value. Pagano Seeds is another source that provides lots of seeds for a good price.

2. Know What to Grow When

Warm-season crops, like tomatoes, should be started indoors and not planted outdoors until the threat of frost has passed.

Seed growers must know when to sow seeds and what to sow indoors in containers or outdoors in the soil. (Click here for Johnny’s Selected Seeds’ helpful Seed-Starting Date Calculator, and click here for a list of warm-season versus cool-season vegetables.) This knowledge saves money because if you sow the wrong seeds in the wrong place at the wrong time they will die or underperform.

Plants for Indoor Sowing: Small-seeded, warm-season vegetables, herbs, and garden flowers, such as tomatoes, peppers, eggplant, salvia, petunias, impatiens, and basil, are best sown indoors in containers. I also start cabbages, kales, and lettuce indoors because they germinate better. I generally wait until plants are 6-inches tall or more before planting them.

Plants for Outdoor Sowing: Large-seeded, fast-growing plants, or those that are sown in rows, are best planted outdoors. Cool-season vegetables, like peas, carrots, beets, and radishes, can be sown outdoors in rows in early to mid-spring. Warm-season, large-seeded crops, and flowers, like beans, corn, okra, sunflowers, and zinnias, can be directly sown in fertile garden soil. I tend to start my cucumbers, melons, and squash in 4-inch pots of Black Gold Natural & Organic Potting Mix outdoors in late spring. They germinate fast, and I let them develop several sets of leaves before planting them in the ground. (Click here to learn more about preparing vegetable garden soil.)

3. Reuse and Recycle

These warm-season herbs (basil, rosemary, and mint) were upgraded into tin cans for outdoor planting.

Frugal growers can cut corners by starting seeds in reused containers. Saving pots from the previous year’s nursery purchases is always an option if you have space, but, reused containers are also useful and educational for kids (reuse, recycle!). Clear plastic ventilated clamshell containers with lids and holes for aeration are especially useful. The lids can come in handy, and once they’ve served their purpose, I just recycle the cleaned containers.

When it’s time to upgrade seedlings into their own pots, there are lots of options, such as yogurt cups, cut plastic bottles, plastic cups, or washed tin cans with holes punched in the bottoms. Be sure to wash containers with hot, soapy water and rinse well before use.  Halved toilet-paper tubes, paper egg trays, or eggshell containers are options for those who prefer paper or natural containers.

4. Choose Cheap Stakes and Labels

Save those Popsicle sticks!

Every kid in grade school started beans or sunflower seeds in a plastic cup labeled with a Popsicle stick. You can still save the sticks as free planting labels. (These, or any wooden label, are best marked with a heavy graphite pencil.) Another option is cutting up large plastic yogurt or cottage cheese containers into strips and trimming them into 3-inch labels. Simply using a sharpy to mark the outside of a cup or container is another option, but it’s always nice to have a label that you can transfer into the garden at planting time.

The most inexpensive stakes for holding up small tomato seedlings are twigs collected outdoors and then cleaned and cut to size. Wooden or plastic stirrers can also serve as small stakes. I usually secure plants with pipe cleaners or soft twine.

5. Soil and Fertilizer

If you want strong, happy seedlings, don’t skimp on soil and fertilizer. Good products will ensure good seedling growth from the start.  Black Gold Seedling Mix is ideal for seed starting. If you’re starting very small seeds, it pays to purchase Black Gold Vermiculite to gently cover them. Not only does vermiculite hold water to keep the seeds from getting dry, but a gentle sprinkling also allows light to pass for seeds that require light to germinate, like lettuce. Diluted, all-purpose, water-soluble fertilizer is gentle enough for small seedlings. Fertilization is not needed until sprouts have begun to put on their second and third sets of leaves.

6. Water for Success

Watering from the bottom will keep seedlings from being displaced and encourage deep rooting.

Using the right watering techniques, from start to finish, is essential to success. Use tepid water–seedlings don’t appreciate the shock of hot or cold water. Keep the soil just moist, never saturated, to avoid seed and seedling rot. To avoid saturated soils, mist the soil surface as needed until seeds have sprouted. Once they have sprouted and start growing, water from the bottom to encourage deep rooting and maintain dry surface soi, which discourages shore flies and fungus gnats. (Click here to learn more about these pests and their control.)

7. Use Natural Light

For indoor plants, the cheapest light is free sunlight that streams through south-facing windows. Ample light is required to keep seedlings from stretching towards the light and becoming long and leggy. Six to eight hours of sunlight should be enough. If you have too little sunlight, fluorescent lights in a shop-light fixture are the least expensive supplemental lighting option. Some fluorescent bulbs are specially designed for plant growth and cover up to 94% of the light spectrum. In general, fluorescent bulbs are not very strong, so they must be placed just inches above plants for best reception and growth. Shop lights are easily set up above a basement bench, along a shelf, or in an informal office space.

8. Always Harden Seedlings Off

Hardening off seedlings prepares them for the travails of the outdoors. (Hardening off means acclimating seedlings from their cushy indoor growing conditions to the windy, sunny outdoors where temperatures fluctuate.) Indoor-grown seedlings are tender, weak stemmed, and need time to adjust. If planted in a tender state, they may develop leaf burn, suffer stem breakage, and die. Harden them off for at least a week before planting. Place the potted plants in a protected spot that gets a few hours of sun per day. Then move them a little more towards the light and in the wind each day. After a week or so, they should be tough enough to plant in the garden.

9. Know When to Plant Outdoors

When sowing seeds directly in the ground, we recommend covering them with a light layer of compost or vermiculite for better germination.

It pays to know when to plant what outside. If your timing is off, excess cold or heat can be deadly.

Spring and Fall Vegetables: Cool-season vegetables, seeds and starts, can be directly sown in the ground in spring as soon as the soil can be worked. Amend the soil with Black Gold Garden Compost Blend, label rows, and cover newly planted seeds with a light layer of compost before watering them in. Keep them just moist, and they should sprout as the soil gets warmer. 

Summer Vegetables: Warm-season vegetables and herbs should be started indoors as early as the start of February, or three or more months before planting them outdoors. (Click here for an article about growing tomatoes from seed.) Plant these and warm-season row crops outdoors after the threat of frost has passed. (Click here to search for your average frost date.)

Perennials: If growing any perennials from seed, start them as early as January. Once they are ready to plant in late spring, they should be large enough for outdoor planting. Keep in mind that many perennials won’t bloom the first year from seed, while others will. [Click here to read an article about easy-to-start perennials that will bloom the first year from seed.]

Annuals: Wait until February to start flowering annuals indoors and March or April to start vining annuals, which often grow very quickly and can take over your indoor growing area. (To learn more, click here to watch the video about growing annuals from seed.)

10. Save Seeds

Seed saving is easy, saves money, and ensures that your seeds have come from a reliable source (your garden!). Smart seed saving requires that you (1) allow your seeds to fully mature, (2) clean your seeds properly, (3) store your seeds correctly, and (4) know exactly what you are saving and storing. Step 4 is essential. If you are collecting seed from a known heirloom plant, you can feel pretty safe that the seedlings will perform like the parent plants. But, if you save seed from a hybrid, expect the progeny to be mysteries awaiting discovery because they may look nothing like the parent from which you collected them. (Click here to learn more about heirloom seeds, and click here for more seed-saving tips from the Seed Savers Exchange.)

(For more vegetable starting tips, click here to learn the 10 steps for creating the ultimate vegetable garden.)

How Do You Harvest and Grow Peony Seeds?

“How do you harvest and grow peony seeds?” Question from Mark of Barrie, Ontario, Canada

Answer: If your peonies successfully cross-pollinated and produced viable seeds that can be induced to sprout, then the plants will develop seed pods that should contain fully mature seeds in late summer or early fall. The round, tough seeds should be harvested as soon as the pods open and begin to turn brown. The seeds will be dark brown to black.

Getting Peony Seeds to Sprout

It takes time and patience to get peony seeds to sprout. Some seeds will produce seedlings in a year and others can take up to three years. Fresh seed will yield the best results. The seeds require a process called stratification, which involves a chilling period of a few months before one can try to induce the seeds to grow. In the case of peony seeds, they need a warm period, chilling period, and warm period. Stratification can be done indoors or outdoors.

Outdoor Stratification

The outdoor method is a little less precise and may take longer, but it often yields the best results. As soon as you harvest your seeds, soak them for three to four days in water. Change the water each day. Unhealthy seeds will float, sink, and become soft. Healthy seeds will swell, and remain round and firm.

Collect the healthy seeds, plant them 1.5 inches down, and 3 inches apart in a flat of Black Gold Natural & Organic Potting Mix. It contains peat as well as composted bark–a combination favored by peony seedlings. Count the seeds and note their placement to keep track of their progress. Also, be sure to label the flat with the planting date, name, and any other essential information. Place the flat in a safe location in partial shade. Keep it moist through the warm days of fall, then cover the top of the flat with plastic wrap in late fall, and let it remain over the winter. Remove the plastic in early spring, and keep the flat moist through spring. The seeds should begin to sprout by mid to late spring. When they emerge, feed them lightly with a water-soluble, all-purpose fertilizer as soon as their second (true) leaves emerge.  Once they reach a few inches, you can transplant them to pots or a location in the garden with good soil. You will need to baby them as they grow. It may be wise to protect them with chicken wire or plastic collars. Placing diatomaceous earth around them should also keep snails and slugs away.

Some seeds may not sprout in the first year. If this is the case, keep the flat in place, maintain moisture through summer, and repeat the stratification process in fall and winter.

Indoor Stratification

Take your healthy peony seeds indoors, place a few in a 4-inch pot filled with Black Gold Seedling Mix. Moisten the pot, and place it under grow lights for a month and a half. Keep the pot moist and make sure the indoor temperature is between 70 and 80 degrees F. After a month, place the pot in an air-filled plastic bag in the refrigerator. The best temperature for stratification is 40 degrees F. Moisten the pot every couple of weeks while it is in the refrigerator–don’t let it get dry. After three months, remove and place it under grow lights. Keep the pots lightly moist, maintain a temperature between 70 and 80 degrees F, and the peony seeds should sprout in a month or two. A heat mat set to warm can help. (Please click here for more detailed information about how to start seeds indoors.)

The American and European Peony Societies are great information resources for additional information. (Click here to read the EU Peony Society’s highly detailed PowerPoint about peony seed starting.)

Happy gardening,

Jessie Keith

Black Gold Horticulturist

Black Gold® Seedling Mix, A Professional Mix for Home Growers

BG-Seedling-1.5cuBlack Gold® Seedling Mix is the perfect medium for germinating seeds and propagating cuttings, and the formula is the same blend used by professional greenhouse growers. Our mix is designed to promote better root development in young plants and holds water well due to the addition of an organic wetting agent. Moreover, it is OMRI Listed®, which means it is approved for organic gardening.

We start with fine, screened Canadian Sphagnum Peat Moss  and fine perlite and vermiculite to give seedlings and cuttings the aeration and moisture retention they need to develop good root systems. An organic wetting agent ensures rapid water penetration, and the fine texture allows growers to germinate even the smallest seeds while also encouraging excellent rooting. Transplanting seedlings and cuttings with strong root systems grown in Black Gold® Seedling Mix is a breeze!

When it comes to germinating seeds, it’s simple working with this ready-to-use product. All you need is water, light, warm temperatures, and Black Gold® Seedling Mix.

Different seeds require different temperatures for best germination—some requiring cool temperatures and others warm. In general, seeds should be kept at temperatures between 60 and 70 degrees F and placed in bright light provided by grow lights or a window with a southern exposure. Some seeds need to be covered with mix to germinate and some require light to germinate and should be sprinkled on the surface of the mix, so be sure to check seed packets for details.

After planting, make sure the growing media stays moist, but not wet, and seeds and/or cuttings have plenty of water in the early stages of germination and rooting. Our seedling mix is designed with both peat moss and vermiculite, essential ingredients when you want to retain just the right amounts of moisture in your soil.

6-packsBlack Gold® Seedling Mix is made with the same ingredients we use to make our seedling/propagation mixes for professional greenhouse growers. Germinating your own seeds or rooting your own cuttings is a rewarding experience and one of the great delights of gardening. So, when you are faced with the question, “Why buy a premium seedling mix?” the answer is clear. Black Gold® Seedling Mix is high-performing and results in robust seedlings and cuttings. Why trust your seeds to anything else?

More seed-starting articles:

Bottom Heat for Happy Seed Starting

Seed Starting Tutorial: Part 1 of 6

Starting Seeds Indoors

Starting Perennials from Seed

Grow Free Bedding Plants with Cuttings

5-Step Vegetable Garden Planning

6 packs
It pays to save six-pack containers from store-bought plants to sow your own seeds. Just be sure to wash the packs before reuse.

The quiet of the January new year is the ideal time to start vegetable garden planning.  This is the month of contemplation when you begin to conjure up next year’s crop in all its glorious diversity.  Whether it’s just an Earth box or a huge family plot, all vegetable gardens start the same way.  Success requires early organization, the ability to assemble exactly what you need, and the ability to time it all to perfection.  In fact, it’s much like planning a holiday meal with a half dozen different dishes that all need to be ready at the same time.  You need to make lists, shop for all the ingredients, and strategize your space in the oven and stove before bringing everything to the table.
Continue reading “5-Step Vegetable Garden Planning”