Growing Tomatoes from Seed to Harvest

By: Jessie Keith

Tomatoes

Nothing is more gratifying than a big tomato harvest in the summer season!

The tomato is the most popular warm-season crop, but it can be surprisingly tricky to tend to full productive glory. Tomatoes require at least 6 hours of full sun per day, are fertilizer and water hogs, and produce fruit most vigorously when days are warm (between 78 and 92 degrees Fahrenheit) and nights moderately warm (at least 70 degrees Fahrenheit). Vining (indeterminate) types need caging or trellising, while bush (determinant) types may or may not need staking; both benefit from seasonal pruning. For temperate growers, late winter is the best time to plant homegrown tomato plants from seed for spring planting.

'Gold Medal' is one of the best-tasting, prettiest beefsteak tomatoes.

‘Gold Medal’ is one of the best-tasting and prettiest beefsteak tomatoes.

These savory fruits come in all colors, shapes, and sizes and flavor is surprisingly variable. In my garden I always choose several slicers, sauce tomatoes, salad tomatoes, and cherries each year. This year’s pickings include the heirloom red and yellow slicer ‘Gold Medal‘, the French salad tomato ‘Crimson Carmello‘, and orange beefsteak ‘Kellogg’s Orange Breakfast‘. My favorite sauce tomatoes are the Italian powerhouses ‘Pomodoro‘, ‘San Marzano Redorta‘ as well as the salad-sized ‘Principe Borghese‘, which is touted as the best tomato for sun drying. My cherry tomatoes of choice are the sweet, golden ‘Sun Gold‘, tiny red ‘Matt’s Wild Cherry‘ and delectable yellow and red ‘Isis Candy‘.  All are beautiful and have exceptional flavor. Here are the basics for starting, growing, protecting, and harvesting your tomatoes for success and high yields.

  • Common Name: Tomato
  • Botanical Name: Lycopersicon esculentum (syn. Solanum lycopersicum var. lycopersicum)
  • Days to Harvest: 65 to 85 days after planting
  • Soil: Rich, porous, friable loam amended with Black Gold Garden Compost
  • Common Problems: Tomato hornworms, damping off caused by Pythium and Phytophthora pathogenic fungi, cool temperatures (causes fruit toughness, cat-facing, and reduced productivity), Colorado potato beetles, and blossom end rot (a physiological disorder caused by calcium deficiency), splitting/cracking (happens to mature or nearly mature fruits on the vine when plants get excessive water or temperatures dramatically fluctuate.)
  • Planting Time: After the last frost date, in temperate zones; in warmer climes, they can be planted at any time of year as long as temperatures are warm enough
  • Fertilization: Feed at planting time with an organic fertilizer formulated for tomatoes, as these always contain sufficient calcium.

Days to Harvest Timeline

'Pomodoro' is a fantastic all-purpose tomato for fresh eating and cooking.

‘Pomodoro’ is a fantastic all-purpose tomato for fresh eating and cooking.

Starting Seeds: It takes around six to eight weeks to grow tomatoes from seed to plantable seedlings. Start seeds indoors for best results.  In 5 to 12 days your tomato seeds should germinate. Germination is best in warm temperatures (68° to 75° Fahrenheit (20-24° Celcius)). A heat mat for seed starting will dramatically hasten tomato seed germination. Sow seeds in cells filled with seedling mix and lightly sprinkle a bit on top to cover. Gently moisten the cells with water and place right under the warmth of grow lights. (Click here for detailed seed-starting instructions.) Tending Seedlings: Tomato seedlings are very delicate and have two lance-shaped seed leaves. True leaves start to appear in 2 to 3 days. Continue to keep plants lightly moist and feed with a diluted all-purpose fertilizer, once the seed leaves have appeared. To avoid leaf burn, lift grow lights up as seed leaves get closer to the bulbs. (*Grower’s warning: Don’t allow soil to become too saturated. Wet soil can encourage fungal disease and cause seedlings to rot or “damp off.”) Tending Small Plants: Tomato plants should be around 8 to 10 inches tall after 42 to 56 days and garden ready. Before planting outdoors, plantlets need to be hardened off for at least a week. Hardening off means acclimating seedlings from their cushy indoor growing conditions 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. To harden them off, place your potted plantlets in a protected spot that gets a few hours of sun per day. Check them daily and slowly place them in a location where they get a little more light each day. After a week of so, they should be ready to plant in the garden.

'Matt's Wild Cherry' is a delicious, tiny cherry tomato with big flavor.

‘Matt’s Wild Cherry’ is a delicious, tiny cherry tomato with big flavor.

Garden Planting: Amend planting beds by digging and turning the soil deeply and adding rich compost and OMRI-Listed Black Gold Tomato & Vegetable Fertilizer. Plant tomatoes around 4 feet apart and mulch with a 2 to 3 inch layer of compost. Young plants can be planted deep, with only a couple of nodes with foliage above ground, but leaves should be gently removed from all stem parts that will be covered with soil. Indeterminate tomatoes should be fitted with a sizable tomato cage right away to support vines and fruits as plants develop. Water regularly to keep plants moist, not wet. Days to harvest vary, but plants usually begin to bear fruit 65 to 85 days after planting. Container Planting: Tomatoes are such aggressive feeders and water hounds, you have to give serious attention to container grown plants. Start with a really large pot. Determinant tomatoes are best, but indeterminates will also work if you keep them caged and pruned. A good organic water-holding potting soil is perfect for container culture. I recommend Black Gold® Moisture Supreme Container Mix, which also contains Resilience™ for stronger stems, more compact growth & better root development. Container-grown tomatoes need to be watered daily and fed more frequently, but if you give them ample attention, they should thrive and produce beautifully.

Black Gold Moisture Supreme Container Mix is a great selection for container-grown tomatoes.

Black Gold Moisture Supreme Container Mix is a great selection for container-grown tomatoes.

Harvest: Tomatoes can be harvested green for fried green tomatoes and green tomato chutney, but they are best picked fully colored and ripe. Some tomatoes are naturally easy to pull from the vine when mature, while others cling to the vine. I always keep a pair of harvest sheers on hand for clingers. If you accidentally harvest a few fruits with a bit of green, let them stand on a sunny window for a couple of days, and they will ripen up right away. Pruning: Tomatoes can be cut back and shaped to keep them from overtaking a trellis or container. Use sharp, clean pruners to cut whole branches back to main stems as needed. Try to maintain productive, fruit and flower laden branches, if at all possible. As a precautionary measure, it is wise to dip pruners in a 10% bleach solution when pruning from plant to plant, just to avoid the possibility of spreading disease. Dip and wipe the pruners after pruning one plant and going to another. Preparation: This is the easy part. Lavish burgers with big, hearty tomato slices, eat them fresh in salads or make homemade tomato sauce  and salsa. To extend the season, freeze whole tomatoes and sauce for winter. (This generally requires at least 10 healthy tomato plants to provide enough to store all winter.) Growing tomatoes is gratifying if you follow the proper steps and give them the best care. If you do it right you should have more than enough tomatoes to enjoy and share. I wish you the best tomato season!

Follow these instructions and you'll have enough tomatoes for storing and sharing with friends.

Follow these instructions and you’ll have enough tomatoes for storing and sharing with friends.

About Jessie Keith


Plants are the lens Jessie views the world through because they’re all-sustaining. (“They feed, clothe, house and heal us. They produce the air we breathe and even make us smell pretty.”) She’s a garden writer and photographer with degrees in both horticulture and plant biology from Purdue and Michigan State Universities. Her degrees were bolstered by internships at Longwood Gardens and the American Horticultural Society. She has since worked for many horticultural institutions and companies and now manages communications for Sun Gro Horticulture, the parent company of Black Gold. Her joy is sharing all things green and lovely with her two daughters.

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