4-Week Old Heirloom Tomato Plants & 10 Tips for Potting Them Up

4-week heirloom tomatoes in 4" pots
4-week heirloom tomatoes in 4″ pots

I’ve had a number of requests to show the growth stages of heirloom tomato plants and pepper plants, particularly at the 4-week stage.  The 4-week stage is fairly important, as that is typically when the seedlings are outgrowing their cells and need to be potted up into larger containers to continue growing strong and vigorous for their permanent bed in the garden or large pot.  Here are some photos of the 4-week growth stage of heirloom tomatoes and tips for potting up the seedlings.

Tips for Potting up Heirloom Tomato Plants:

  1. 4-week heirloom tomatoes still in flat
    4-week heirloom tomatoes still in flat

    As you get ready to pot up young heirloom tomato plants (or pepper seedlings), a better indicator of timing than the 4-week period, is to pot them up after they have two sets of true leaves (do not count the seed leaves at the bottom).

  2. Handle the seedlings by the leaves rather than the stems.  If you tear a leaf, the plant will still grow.  If you break the tender stem, the plant is ready for the compost pile.
  3. 5-week old pepper plants
    5-week old pepper plants

    I grow my initial heirloom tomato plants in 196-cell trays, and when it is time to pot up I take a butter knife and gently pop the plant out of the cell with the soil bundle (aka a plug) intact.  Have a 4″ pot ready with moist potting soil and make a hole with your finger in the center of the 4″ pot.  Place the seedling plug into this hole and gently press the soil around it to make contact with the roots.

  4. If you grow many seedlings in one container rather than in cells, you will need to tease apart the roots from each seedling and then place in the hole of the 4″ container.  Alternatively, you can snip off the weaker seedlings at the soil line and leave the strongest plant in the container to take advantage of the nutrients in the remaining soil.  Remember…don’t handle the seedlings by the stem!
  5. Newly potted up heirloom tomato plants may look limp and stressed the first day or two.  Don’t fret and do anything drastic like fertilizing them.  They will recover with a couple days rest in the same environment they were in prior to potting up.  Keep them out of bright sunlight for a couple of days.
  6. When potting the heirloom tomato plants up to larger pots, plant them a bit deeper than they were in the cell or original container.  Additional roots will form along the buried stem and give you a more vigorous plant.  You can cover the seed leaves and plant right up to the lower set of true leaves.
  7. Use the same potting soil that you used to start your seeds…not garden soil.
  8. Water the tomato seedlings in their cells or container well BEFORE you start to pot up.  Moist soil will cling to the roots and protect them from drying out.
  9. Depending on the weather and when you are going to put the heirloom tomato plants in their permanent bed, you may want to pot up a second time.  A good rule of thumb when deciding when to do the second transplant is to wait until the height of the seedling is three times the diameter of its pot (probably around 6-10″ tall).
  10. Trouble shooting:  If your heirloom tomato seedlings are getting tall and spindly, it may be related to:
  • the light source may be too weak or too far away from the growing tip;
  • the room temperature may be too warm (I keep my daytime temperature around 70 degrees and the night temperature around 50 degrees; or
  • you are using too much fertilizer.  Just use potting soil that already has fertilizer in it or use potting soil with compost.  Wait until they are outside before getting more generous with fertilizer.
April 19, 2013 in Forest Lake, MN
April 19, 2013 in Forest Lake, MN

This is the longest, coldest winter we have had here in Minnesota, and while my heirloom tomato plants and pepper seedlings are currently quite happy in their protected environment, they will be hurting soon if we can’t get them hardened off.  It is April 19th and 4″ of new snow on the ground, and still snowing!!  Ugh.  I haven’t given up hope that we will have a long warm summer, but spring is looking pretty doubtful.  As a farmer, you do learn to roll with the punches, but I have to admit this is getting pretty depressing.

Growing Heirloom Tomatoes in Pots: Best Heirloom Varieties & Growing Tips

Basket of Heirloom Tomatoes grown at HeathGlen
Basket of Heirloom Tomatoes grown at HeathGlen

Basically, any heirloom tomato plant will grow in a pot with proper growing techniques, but some are definitely easier to manage than others.  The most reliable way to grow heirloom tomatoes in pots, if you are a novice grower, is to start with “Determinate” varieties.  Determinate varieties only grow to around 3-4 feet and therefore often don’t require staking and trellising with the pot (whereas “Indeterminate” varieties grow until frost and may get 7-8 feet).

The main difference between determinate and indeterminate varieties, in terms of fruiting, is the timing of fruit production.  Determinate varieties will produce all of their fruit over a 2-3 week period rather than continuing to produce throughout the growing season.  This doesn’t mean you get fewer tomatoes from a determinate, you just get the crop in a shorter time frame.

This is a breakdown of my personal favorites for container-growing, categorized by Determinate vs. Indeterminate and Heirloom vs. Hybrid:

Favorite Heirloom Determinates for Pots:

  • Principe Borghese:  A fairly large determinate plant with small egg-shaped fruit that pack a high flavor punch (more acid than sugar).  Prolific & great for drying or to use in salads.
  • Manitoba:  This slicer was developed in Manitoba, Canada, to ripen during the short summers of the Manitoba prairie. Vigorous and early.
  • New Yorker:  Bush Beefsteak type, yielding 4-6 ounce meaty tomatoes with balanced flavor.  Plants set well in cooler growing conditions.

Favorite Hybrid Determinate for Pots:

  • Bush Champion:  Low maintenance compact plant that grows about 2 feet high, with larger (8-12 oz) tomatoes than most early determinates.  Stocky stems that don’t need trellising.  This is the one I usually  recommend to novice growers that just want to make sure they get tomatoes they can use on their BLTs.

Favorite Heirloom Indeterminates for Pots

  • Green Zebra Heirloom Tomatoes
    Green Zebra Heirloom Tomatoes

    Japanese Black Trifele:  ‘The fruit color makes this a nice ornamental as well, and the plants are fairly compact as well — one strong stake should support the plant well.  Delicious complex, smoky flavor and beautiful bronze color.

  • Green Zebra:  While considered an indeterminate tomato, they are much less rangy and grow more compactly, reaching about 5-6 feet high depending on your climate.  Very poplar for taste, with a tart, slightly lemon background balancing the sugar.  A favorite of many for its unique looks also.
  • Stupice:  Perhaps the earliest heirloom, the plants are compact and the fruit is small, but it produces well all season.  Overall, know that early tomatoes tend to not be as flavorable as main season tomatoes.  For an early tomato, Stupice is one of the more flavorable ones.
  • Paul Robeson:  Beautiful, dark purple 3-4″ tomato with intensely sweet and smoky flavor and a juicy, smooth texture.  Needs staking, but well worth it.  Early
  • Other good alternatives include:  Eva’s Purple Ball, Gardener’s Delight, Matts Wild Cherry,
Carmello Indeterminate Tomato Variety
Carmello Indeterminate Tomato Variety


Favorite Hybrid Indeterminates for Pots:

  • Carmello:  Reliable and prolific, with intensely flavorable, 8 oz., juicy red fruits.  Disease resistant and a great overall main-season tomato which produces good flavor even during the colder part of the season.
  • Sungold: Sweet, prolific and very popular cherry tomato.  Most cherry tomatoes will do well in containers, as they grow tall but their fruit is small and they don’t tend to sprawl as much.



Size of Pots for Growing Heirloom Tomatoes:

  • Variety of Attractive Plastic Pots for Growing Tomatoes
    Variety of Attractive Plastic Pots for Growing Tomatoes

    The bigger the container, the better.  Keep in mind that tomatoes grow large root systems, and they need room to develop for best production.  A large container will also prevent the soil from drying out too quickly during the heat of summer.

  • Minimum size:  In general, a 5 gallon container is considered the minimum size.  If you use a smaller pot, you are likely to have problems with the potting mix drying out, which can lead to blossom end rot (see this post to help with blossom end rot).  The larger indeterminate heirloom tomatoes will grow well in 12-18 gallon containers.   A container 12 to 18 inches deep for all tomatoes is generally a good rule of thumb.
  • If you are using a container of your own creation, make sure and punch holes in the container bottom to allow excess water to drain properly.
  • Be aware of how heavy your containers will be after watering. If you need to move the container to follow the sun, think about buying (or making) a container with wheels under the pot so you can move it around without breaking your back.

Location Considerations:

  • Sun:  Keep in mind that tomatoes need around 6-8 hours of sun a day.  Try to avoid a really hot afternoon sun if possible.
  • Wind:  Avoid areas that are susceptible to strong winds.  Hot dry winds are probably the most detrimental condition for young plants, causing their leaves to shrivel and die.  Strong winds can break the young plants at their growing tips, or topple over and break staked older plants.  If you are growing on a deck or balcony you may have to look into some form of protective barrier.
  • Staking:  If growing indeterminates, place your stakes or cages early and train the plants to grow vertically, allowing as much sunshine as possible to penetrate to the inside of the plants.  Secure the stakes or cages well…larger tomatoes can be very heavy.

Soil/Potting Mixes for Pots:

  • Potting Mix Moisture Level
    Potting Mix Moisture Level

    Don’t use soil.  Tomatoes grown in containers need a loose, well-drained medium with lots of organic matter.  Use a good potting mix rather than potting soil or garden soil. Potting soil can be too heavy for containers, and soil harvested straight from the garden is most likely infested with fungi, weed seeds, and pests.

  • Potting medium:  Use a high-quality mix containing peat moss and perlite.  If preparing your own soil-less medium, blend in a complete fertilizer, either a dry organic product, such as one containing alfalfa meal, bonemeal, kelp meal, or other natural nutrients.
  • Compost:  I am a great believer in the benefits of good compost.  It can add the micro-nutrients that potting soils might be missing and it can aid with drainage and moisture control.   I use a ratio of 3:1 soil-less mix to compost.

Fertilizing Container-Grown Heirloom Tomatoes:

  • Organic fertilizers:  Make a compost tea or manure tea and fertilize monthly during the growing season.  Other good organic fertilizers are liquid fish emulsion and liquid seaweed, which can be applied weekly.
  • Commercial fertilizers:  When you buy your potting mix, you can get one containing slow-release fertilizers, which will help with the growth stages of the plant.  Tomatoes grown in containers will usually demand more fertilizer than the initial timed-release fertilizers to carry them through the entire growing season.  You may need to add liquid water-soluble fertilizer products to the irrigation water as the season progresses.   Follow product directions for concentrations and timing.
  • Time-release fertilizers:  A popular product for containers is Osmocote Plus at planting time. This is a 15-9-12, time release granular product which is supposed to feed up to 6 months.  A fellow gardener, experienced with container plants, recommends following up the Osmocote with Peters 20-20-20 water soluble every 10 days to two weeks.

Watering Considerations:

  • Water regularly. Containers dry out more quickly than regular garden beds, and tomatoes are more likely to develop issues such as blossom end rot if they get uneven watering.
  • Under-watering:  The best way to know if your plants need watering is to check the soil.  Stick your finger in the soil and if it is dry an inch down into the soil it is time to water.  Containers are above ground and dry out quickly.  When the plants are small, water use won’t be as high, but when they are large and setting fruit you will need to water daily.  Do not allow containers to dry completely or fine roots will die. Also, if allowed to dry excessively, the potting media will shrink away from the side of the container and will be harder to re-wet.
  • Over-watering: As long as you are using a potting mix that drains well you shouldn’t be afraid to water heavily.  Good drainage solves most over watering issues.  Make sure your containers has drainage holes in the bottom of the pot.  Back off the watering a little during fruit set to prevent splitting fruit. 
  • Type of container:  Plastic containers do not dry out as quickly as clay, especially unglazed clay pots. Even plastic containers may require daily watering however, as plants grow larger.
  • Self-watering systems:  There are a range of self-watering pot systems that can reduce watering maintenance.  Probably the best known, and longest trialed of these is the EarthBox 1010039 Organic EarthBox, Terracotta.  Although I have never used one, the reports from my customers at the farmers’ markets are all positive.  The EarthBox works by wicking moisture out of a reservoir in the bottom of the planter.
  • Well Water:  occasionally there can be problems from watering with well water.  Water from wells is often high in salts or carbonates which can cause problems. One way to prevent excessive salt buildup is to water thoroughly enough to ensure that 10 percent of what is added drains out the bottom. Salt build-up is damaging to plants causing burned leaf edges, stunted growth, and fewer blooms.  Along this line, if

     saucers are used to catch drained water, empty them to prevent salt buildup.

Signs and Solutions of Nutritional Deficiencies in Heirloom Tomato Seedlings

Young heirloom tomato seedlings will often show signs of nutritional deficiencies in their leaves, and if you know what to look for you can remedy it fairly easily.  Whether planting your heirloom tomato in the ground or in a pot, starting off with a healthy plant is the best prevention of later diseases that commonly plague all tomato plants.

If your seedlings are compact and not leggy, have green leaves, and a short distance between each set of leaves (short internodes), you’re good to go.  If somewhere along the line before you’re ready to plant out in the garden your seedlings start to show signs of trouble, treating it right away will often save the health of the plant.

First Order of Defense when Starting Tomatoes from Seed:

If you are starting your own tomatoes from seed, there are 3 keys to preventing nutritional deficiencies:

  1. Use clean potting soil rather than garden soil.  You can purchase good garden soil from most stores.  Miracle Grow Moisture Control is a good one.  If you want to go completely organic with your potting soil, see this post for a formula.
  2. If you start your seedlings in a flat with small cells, or a small container, pot up your plants when they have two sets of true leaves.  I go from a 196-cell flat to a 4″ pot to the garden and it has been a successful gradation for 15 years now.  There is not much soil in a small cell, hence the nutrient supply is rapidly depleted from the growing plant.
  3. Carefully control your watering regime.  Dryness and water logging can both make it difficult for plants to take up soil nutrients.  I water the seedlings once a day or less, taking my cue from how dry the soil looks (i.e., if the soil is light in color, then water; if it is dark it is still moist and doesn’t need more water).  I also use an indoor watering hose to water, as you can regulate the amount of water you’re giving the little cells much easier than a watering can with a spout.  I’m currently using The Rumford Gardener GA1001 40 Foot Indoor/Outdoor Garden Coil Hose with Spray Wand, as it is the only one I could find.  It seems to work just fine, as long as you have the coil at a height higher than the nozzle.  My old indoor watering hose had a great nozzle that regulated flow better, but it is no longer available (I have to admit it was cheaply made and broke every other year but when it worked it was the best).

Symptoms & Solutions for Common Nutritional Problems in Heirloom Tomato Seedlings:

A.  Symptom:  Yellowing of lower leaves.

  • Probable Cause:  Magnesium deficiency or overfertilizing.
  • Solution:  Decrease the amount of fertilizer you are giving the young plants.  If you used the Miracle Grow Moisture Control potting soil, you probably won’t need any extra fertilizer until they are planted outside.  If you haven’t given any fertilizer, it could be a lack of magnesium and you can water with a weak solution of Epsom salts. Over-use of high-potassium fertilizers can cause magnesium deficiency, as plants take up potassium in preference to magnesium.

B.  Symptom:  Pale green leaves

  • Probable Cause:  Not enough light or a Nitrogen deficiency
  • Solution:  If the seedling is getting plenty of light (16 hours of light/day is good), transplant the seedling to a container with fresh potting soil that contains nutrients; mix some compost in with your potting soil to ensure a nutrient supply.

C.  Symptom:  Purple leaf-tints with bronze or brown leaf edges.

  • Probable cause:  Plant is overwatered or has a Potassium deficiency
  • Solution:  If you are not overwatering (see above tips), give the plant a dose of fertilizer that contains trace minerals or transplant to a new medium with compost.

D.  Symptom:  Reddish purple undersides of leaves, accompanied by slow or stunted growth.

  • Probable Cause:  Phosphorus deficiency due to cold soil or acid soil
  • Solution:  Soil that is too acid or too cold can make it difficult for the plant to uptake phosphorus.  Transplant to new soil and do not water with cold water.

Graphical Portrayal of Deficiencies:

The graphic below is helpful in pictorially describing the symptoms I outlined above.  Unfortunately, I copied the graphic a while back for my own information, and can no longer remember where it came from, so I am at a loss as to who to credit.  If anyone knows which site this graphic came from, please comment below and I will credit them.

Graphic of Nutritional Deficiencies
Graphic of Nutritional Deficiencies

Resource for More In-Depth Information:

A very in-depth look at deficiencies in essential minerals of plants can be found here.  Although Mr. Berry’s book is not focused on the young seedlings before they are planted out, he goes into great scientific detail on the causes and remedies of nutritional deficiencies in plants.  The most helpful part of his work might be the photos however.  They are great photos showing in detail what some of these deficiencies look like on the plant (fortunately I could not take these photos, as my plants have not succumbed to the diseases on our farm).

Comments and questions are welcome.

Heirloom Tomato Varieties: Flavor Profiles Related to Color

HeathGlen's Heirloom Tomatoes in September
HeathGlen’s Heirloom Tomatoes in September

The popularity of heirloom tomatoes is based around two characteristics – their stunning array of colors and the unique flavor profiles of each variety.  The sheer number of heirloom varieties with unique flavors can be overwhelming however.  Fortunately there are a few generalizations that can be made with regards to the relationship between flavor and color.

Taste Tests across the Country:

Many gardeners, chefs and  seed companies have performed taste tests on the most popular heirloom tomatoes, resulting in a wide range of opinions.  Because the flavor of heirloom tomatoes is so dependent on climate and growing conditions, the most reliable taste tests are those that were trialed as close to your home and garden as possible.  We do taste tests at HeathGlen Farm in Minnesota every year, both at the farm and at the farmers’ market in St. Paul.  The list of flavor profiles below are based on our farm’s taste tests.  Some notable taste tests that I have reviewed around the country include:

Six Keys to Selecting Heirloom Tomatoes for their Flavor:

  1. Flavor profiles are based on the most fully flavored fresh-eating tomatoes, not on which heirloom tomatoes are best to cook with.

    Heirloom Tomato Varieties
    Variety of Heirloom Tomatoes
  2. When a review notes that the tomato has a “classic” or “old-fashioned flavor”, it is referring to a balance of acid and sugar in the tomato, getting as close to 50/50 as possible;
  3. An important characteristic that plays into a tomato’s flavor is texture (aka “mouthfeel”).  Generally, if a tomato is said to be mealy, the texture is enough to detract from the flavor
  4. The flavor profiles based on heirloom tomato color are generalizations only.  For example, pale yellow tomatoes tend to be mild and low-acid.  Limmony, however is a yellow tomato that has a very strong acid background, giving it a robust  “lemon-like” flavor.
  5. I have not included cherry tomatoes or plum & paste tomatoes, as they cannot be as easily grouped into color-taste profiles.  In general the cherry tomatoes are sweet, the paste tomatoes are meaty and higher acid, and the plum tomatoes are juicy and mild.  I will put together a separate post on the pros and cons of various cherry and paste tomatoes later this season.
  6. Finally, flavor profiles of each variety are not only subjective to an individual’s taste buds, but are highly variable depending on growing conditions (heat, water, type & rate of fertilizer, number of growing days, etc.)

The Big Pink Heirloom Tomatoes:

Pink Heirloom Tomato Varieties - 2012
Pink Heirloom Tomato Varieties – 2012

The large pink tomatoes offer up what most of us think of as a classic tomato flavor — a balance of acid and sweetness. The most well-known (not necessarily the best tasting) of the pink heirloom tomatoes is the Brandywine.  It has become the standard-bearer for the pinks, as it is a good size for slicing and typically has that bursting blast of tomato flavor most people want in a tomato.

  • Brandywine —   a sweet tomato, offset by a notable acidity that achieves a balanced rich, succulent, old-fashioned home-grown tomato taste.  Depending on growing conditions, it can also be low-sugar, low-acid and fairly bland.
  • Mortgage Lifter —   known for its mild sweet flavor and meaty texture, this pink-fleshed beefsteak can tip the scale at two pounds.
  • Caspian Pink — similar flavor profile to Brandywine, and frequently beats Brandywine in taste tests.  Pro is that it is earlier than Brandywine
  •  Prudens Purple — another early Brandywine type.  Considered sweet, juicy and meaty; doing well in short-season areas
  • Cherokee Purple — sometimes included in the “black” category, Cherokee Purple has a complex flavor with an initial smokiness followed by a slightly sweet aftertaste.   Often compared to a zinfandel wine.

The Black (or Purple) Heirloom Tomatoes

"Black" Heirloom Tomato Varieties
“Black” Heirloom Tomato Varieties

While often referred to as “black” heirloom tomatoes, most of these varieties are more of a maroon or purple-brown color. Black tomatoes tend to have an earthy, almost smoky sweetness to them, with a bit less acid than red tomatoes.  The flavor profile is often referred to as “smoky, complex and wine-like”.

  • Paul Robeson — of fairly recent popularity, Paul Robeson is getting  good marks all around the country for its “smoky,” “complex”  distinctive flavor.
  • Purple Calabash —  often compared to red wines such as Cabernet.  The taste is rich and full of old-fashioned tomato flavor with just the right blend of sweetness and acidity.  The flesh is smooth and meaty with evenly distributed seeds.
  • Japanese Black Trifele — a pear shaped variety. Flavor is deep, chocolatey, smoky, and rich.
  • Carbon — among the darkest of the black tomatoes.  Exceptionally rich and sweet flavor.  My favorite black.
  • Black Krim — intense, slightly salty taste.
  • Black from Tula — perceived by many as the “best-tasting black”, with thin skin and a sweet, complex flavor.
  • Vorlon — cross between Prudens Purple and Cherokee Purple resulting in meaty, rich, sweet taste.  Lynne Rosetto Kasper’s favorite black in 2011.
  • Purple Russian — the best black tomato in a plum variety.  Meaty, sweet and excellent for salads and sauces.

The Red Heirloom Tomatoes:

Red Heirloom Tomato Varieties - 2012
Red Heirloom Tomato Varieties – 2012

Bright red heirlooms are often mistaken as hybrid tomatoes at market, as they look very similar.  Red heirlooms however, are more varied in their flavor profiles than hybrids, tending toward the robust, higher acid flavors.  The reds and the pinks are often what people are thinking of when they ask for that “old-fashioned flavor”.  Red heirlooms also tend to have thinner skin than hybrids, making them less amenable to shipping.

  • Costoluto — “old-fashioned tomato flavor”; performs well when skinned and used in slow simmered sauces.  The flesh is meaty with an abundance of juice and tart tomato flavor.
  • Druzba — smooth, juicy fruits with robust sweet-tart flavor; meaty and great for canning.
  • Legend — Introduced at Oregon State University as highly disease resistant variety. Nice blend of sugar and acid.
  • Aussie —  big, impressive beefsteak variety. Old fashioned, big robust tomato taste.
  • Stupice — best flavor I can find in an early tomato (early tomatoes tend to lack flavor); small
  • Thessaloniki — prolific crack-free heirloom with a meaty, classic flavor; sometimes considered “earthy flavor”
  • Carmello — considered by the French to have the “perfect acid-sugar balance” .  Productive, with juicy texture.  Dona is a smaller version of Carmello.


The Striped Heirloom Tomatoes:

Striped heirlooms (sometimes called marbled), are beautiful and they tend to have a rich, juicy, super-sweet flavor that is low in acid.

  • Striped & Orange Heirloom Tomato Varities - 2012
    Striped & Orange Heirloom Tomato Varities – 2012

    Striped German — almost candy-like flavor.  Sometimes a soft tomato.  Beautiful.

  • Big Rainbow —  considered one of the prettiest and most unique heirloom tomatoes. This meaty beefsteak tomato is known for its sweet and flavorful taste. The golden orange color with artful swirls of red and yellow are seen throughout the tomato
  • Gold Medal —  popular for its appealing sweet taste and marbled beauty,  originating from the Black Forest region of Germany.
  • Flavor Profile: rich, juicy, super sweet flavor that is low in acid.
  • Pineapple- Orange and red on the outside, and yellow with blushes of red on the inside. Very sweet, low acidity and nice flavor.

The Orange Heirloom Tomatoes:

Orange tomatoes (not yellow), are mild, sweet, and are low-acid. They are the varieties that will most remind you that tomatoes are, botanically speaking, fruits.

  • Persimmon — One of the best flavors of all the orange tomatoes. Meaty with few seeds.  Creamy meaty, texture.  .
  • Juane Flamme — small (large plum size), sweet and low-acid, bursting with juice.  Almost a tropical flavor.  My favorite small orange.
  • Kellogg’s Breakfast — vibrant sweet taste, meaty with few seeds.

 The Green Heirloom Tomatoes:

Green Zebra Heirloom Tomatoes
Green Zebra Heirloom Tomatoes

The commonality of green tomatoes is a bright acidity, but the degree of sweetness tends to vary quite a bit.

  • Aunt Ruby’s Green — bright with acidity, but well-balanced with sugar.  Incredible juiciness.
  • Green Zebra — tangy and zingy are adjectives often attached to Green Zebra.  Very popular for taste and eye appeal.

The Yellow (or White) Tomatoes:

White tomatoes aren’t really white. They’re more of a pale yellow. Yellow and white tomatoes  are noticeably less acidic than red tomatoes. Some consider them the sweetest tomatoes and some consider them the blandest tomatoes.  The common factor is low-acidity.

  • Yellow & White Heirloom Tomato Varieties
    Yellow & White Heirloom Tomato Varieties

    Great White- yellow on the outside, and pale yellow on the inside.  A very mild flavor with low acidity, and  a hint of sweetness.

  • Limmony — a yellow beefsteak with a strong, zesty, sweet citrusy flavor. It is also sometimes spelled Lemony.


5 Tips to help with Tomato & Pepper Seed Germination

Newly Germinated Seeds
Newly Germinated Seeds

Although there are many factors to consider in growing healthy tomato plants from seed, getting the seeds to germinate in the first place can sometimes be tricky.  After 15 years of growing peppers and tomatoes for market, I’d like to share a few tips that have helped influence germination success at my farm.

1) Seed Viability Relative to Germination:

  • Shelf life:  Tomato seeds tend to last much longer in storage than most other seed (i.e., onions need to be purchased fresh every year).  Just make sure they were stored properly (cool & dry) and you should have around a 4-5 year shelf life for tomato seeds.  Pepper seeds are considered by most growers to have a 2-3 year shelf life.  Fedco seed company puts out an informative chart on saving seeds, which includes estimates of shelf life for a range of vegetable seeds.  Click here for Fedco chart.
  • Storage:  Humidity shortens the life of saved seeds more than any other aspect.  Make sure seeds have wintered over in a cool and dry environment (such as in a tightly sealed jar in the refrigerator or freezer).  Dry storage at less than 65 degrees F will give you good germination results.
  • Vigor:  A number of online gardening sites explain how to test a few of your seeds for germination before planting.  Just be aware that even if your older seeds germinate, if they are too old or shriveled they may have a scant supply of food stored in their endosperm and the plants may end up weak and/or stunted.

2)  Seed sowing tips:

  • Potting soil can be fluffy with air and seeds need to make good contact with the soil in order to germinate.  Moisten your potting soil before placing it in the flat or container, drop the flat on the ground from a few inches above the floor to settle the soil into the container cells, and then make sure your seed makes direct contact with the soil.  I use a #2 pencil to lightly push the seed into the cell and then use the pencil to push a bit of soil over the seed with enough pressure to make sure it securely covered
  • Very fine seeds do not need to be covered, just press them lightly into the soil.  A few seeds need light for germination (check your seed packages for which ones).
  • General rule of thumb is to cover seed to a depth of three times their size.

3)   Water & Germination:

  • Water must be available to the seeds in order for them to germinate, but some air must also reach the seed for it to absorb the oxygen it needs.  I mix my potting soil with very hot water until it is damp but not soaking wet.  A good test is to squeeze a fistful of your moistened soil, checking to see if only a few drops of water squeeze out rather than a stream.
  • Check your flats daily to make sure they have not completely dried out.  If they become too dry, moisten them gently with a spray bottle.  Peppers, in particular, do not like to germinate in wet soil.

4) Timing & Temperature:

  • The length of time it takes for your seeds to germinate is heavily related to soil temperature.  Tomato seeds should germinate within 5-6 days if you can keep the soil temperature around 80º F.  Peppers take a little longer with a little higher temperature (7-8 days at 85º F). Remember this is soil temperature, not ambient temperature.
  • Speeding things along:  I usually get germination earlier than the standard charts predict by placing bottom heat under my flats using 100-watt light bulbs (see this post for my seed-starting setup).  A nice infographic on the relationship between temperature and timing of germination can be found here from Easy Homesteading.

5) Special Germination Tricks for Difficult Seeds

  • Pre-soaking seeds:  Soaking seeds in warm water overnight before planting helps to soften the seed coat and speed up germination.   Many seeds, even if it is not stated in their steps of seed germination, will benefit from pre-soaking.  I don’t usually pre-soak tomato and pepper seeds, but I always pre-soak parsley, sweet peas and nasturtium seeds
  • Scarifying seeds:  This refers to the process of literally damaging the seed coat, usually by scratching the seed with sandpaper and then soaking in water.  Some seeds (i.e., woody plants in the legume family) are so hard and well protected by their seed coat that the seedling is not able to break through it on its own.  Tomato and pepper seeds do not need scarifying, but some of the larger seeds with hard seed coats would benefit from this.
Seed-Starting Reference Book
Seed-Starting Reference Book


I have been starting tomato and pepper seeds for market now for 15 years.  The book that I found to be most useful throughout my adventure is The New Seed Starter’s Handbook, by Nancy Bubel.  This book is research-oriented, comprehensive, and provides the scientific rationale behind each method she promotes.  For more thorough information on the tips offered in this post, I would highly recommend Nancy Bubel’s book.