News for those who live, work and play in the Santiam Canyon

All you need to know about tomato plants

OSU Linn County Master Gardener.

What’s wrong with my tomatoes? Master Gardeners are getting that question a lot as tomatoes should be ripening. 

If you haven’t picked your first ripe tomato of the season, you’ve lost the contest of earliest harvest. There is still plenty of season ahead until first frost. 

Some folks are growing a single “love apple” plant in a container, lavishing attention on it, perhaps singing or talking to it. Others have rows of sprawling plants in the back yard. Most have no idea what kind of tomato they have. Others will proudly name their heirloom varieties for us.

Have lots of leaves with few fruits or flowers? Too much nitrogen, not enough phosphorus. The middle number on the fertilizer package (N-P-K, 5-10-5 for example) indicates the proportion of phosphorus, an element that encourages plants to flower and fruit. Work a little high-P fertilizer into the soil and water it in to get it to the roots. 

Try pruning off all the branches below the first flowering branch, so the energy will go to the flowers and fruit instead of useless greenery. If the plant is bushy, prune out more non-flowering branches so the nutrients can be captured by the flowers.

Have flowers that are not producing fruit? Try petting your plants – be the wind. Tomatoes are self-pollinating, relying on wind movement to carry pollen from one flower to another. They do appreciate insect pollinators, especially bumble bees, but do not require them. 

If you are really obsessed with being the bee, try a soft paintbrush to spread the pollen from one cluster to the next. Or make sure there is a breeze available, even if you have to plug in a fan on the patio. The air movement also helps prevent some diseases also.

Is your tomato climbing and sprawling out of bounds? You have planted an indeterminate tomato – as opposed to a determinate “bush” variety. Provide support, up to 8 feet or more in some cases. The top growth is expanding to catch the sun, while the fruits are appearing from the bottom up. 

As the fruits ripen, prune the foliage up to the next fruiting spur that needs the nutrients. If the top is too tall, espalier the branches sideways with support for future fruit. You’ll need more space because there is still plenty of time for them to continue growing.

Are there large grey, brown or black spots on the blossom end of the fruit opposite the stem? 

That is blossom end rot disease – common when the fruits are enlarging. It is not a fungus, but simply a lack of calcium in the soil, and/or very wet or very dry soil. 

Are you watering the soil regularly, especially on mornings of hot days? The moisture is important for uptake of nutrients. Did you work a handful of lime into the soil when you planted? It won’t hurt to work some into the soil near the root now, but it will have to dissolve to be taken in by the plant so results may not be noticeable before the season ends. 

Some gardeners proudly say they added Epsom salts to the soil. Our soil already has enough magnesium, so Epsom salt is not helpful here. It would be better to spray the leaves and fruit with a solution of two tablespoons of calcium chloride in a gallon of water. Take care not to wash the solution off, watering the soil below the plants instead. 

As for the affected fruit, just cut the ugly spot off and eat the rest of the tomato.

Pick the fruit when it is just slightly under ripe. It should feel firm with just a little “give.” The color should be close to mature color, with perhaps a little green on the shoulders. The tomatoes should be east to pull off the vine. 

To harvest large tomato varieties, hold the fruit in your hand and twist it off the vine. Grape and cherry tomato varieties should be individually hand picked, or cut off the entire cluster with clippers or scissors. 

Store ripe tomatoes in a plastic bag in the refrigerator for four to 10 days. Green tomatoes will store one to six weeks in the refrigerator, then can be taken out to ripen at room temperature as you need them. 

One medium-sized tomato provides about 25 calories and 1 ½ grams of fiber. They are an excellent source of vitamin C and a good source of vitamin A. 

Many people brag that their heirloom tomatoes have more flavor. They are certainly available in more colors and shapes than commercially bred varieties. The term “heirloom” refers to varieties that have been cultivated for a hundred years or more from saved seed. 

Some heirloom tomatoes originate from other areas that have different climates and may not be as happy to grow in our microclimate. Other heirlooms, like Brandywines, are unstoppable in the Canyon and produce huge slicers. Ours were up to 1 ½ pounds each last year. 

If you have a specific problem in your garden from insects, nutrition or growing conditions, call your county OSU Extension Office for advice from a Master Gardener who has been trained to diagnose plant problems. 

Ask an expert by email at, with a picture of the problem if you can, and they will get back to you with information about causes and possible solutions.

Previous Article

How to get rid of tansy ragwort

Next Article


You might be interested in …

Sustainable gardening can ease yard maintenance

OSU Linn County Master Gardener. Is your yard and garden sustainable? A sustainable garden can thrive with as little labor, water, fertilizer and pesticides as possible. It requires a bit more planning to achieve a […]

Time to get a head start on spring

By Diane HydeOSU Linn County Master Gardener Tired of winter yet? Get a head start on Spring with a few garden tasks between rain showers. Getting organized for outdoor activity improves the mental state, knowing […]