TOMATO GROWING TIPS

When and Where to Plant

Tomatoes need night time temperatures that are consistently above 55°. If tomatoes are planted too early, they will become stunted and more susceptible to disease, and will take longer to blossom and fruit in your garden. 

Tomatoes need full sun. This means at least 7- 8 hours/day of direct sunlight, 10 hours/day is optimum. 

How to Plant

Plants need to be spaced 24” apart for determinates, and 36” apart for indeterminates. Rows should be 36”- 48” apart.

Dig a hole at least 15”-18” deep. Remove rocks from the soil, add a generous shovel full of compost along with a handful of granular organic fertilizer (Tomato-Tone or any other good organic granular fertilizer), and mix thoroughly. If you’ve had problems with blossom-end rot, add a handful of crab shell as a preventative.

Remove the foliage from the bottom ½ of the plant so that it looks like a palm tree. Place some of the amended soil back into the hole so that when you place the plant in the hole the remaining foliage will be above the soil line. When tomatoes are planted like this, some of the hairs you see along the stem will turn into roots creating a larger, more substantial root base. 

Once the plant is placed in the hole and BEFORE filling the rest of the hole with your amended soil, fill the hole with water – this will thoroughly water your rootball as well as the area into which it will be growing. Wait until the water has completely drained out, then back-fill with your remaining soil and press down firmly to ensure good contact with the roots. Leave a circular depression in the soil around the plant to hold water when watering in the future. Then water again. With this method, you shouldn’t have to water again for at least a week because you have watered deeply.  

Top the soil with a few inches of straw hay or other mulch to conserve moisture and cut down on weeds. 

Place your tomato cage around your tomato at planting time.  It’s easier to do when they’re small, and also ensures that you’re leaving enough space between plants. 

Fertilizing

A month after planting, pull back the mulch and spread 2 handfuls of granular organic fertilizer and 2” of compost around the base of your plant. Your tomato is growing hard at this point, so you want to give it adequate food to keep it healthy. 

Repeat this fertilizing in another month.

Tomatoes like a soil ph of 6.5, but anything in the range of 6.2-6.8 is fine. If you want to test your soil ph, check out the soil testing offered by UMass soiltest.umass.edu. 

Watering

Tomatoes require 1” of rain a week. If the forecast doesn’t supply this, then you should water your garden deeply and thoroughly once a week. 

It is best to water in the morning, before the heat of the day. Watering at night can promote fungal diseases on the damp leaves in the cooler night air. If you must water at night, make sure you water the soil and not the leaves of your plants. 

Scratch the surface of the soil to see if indeed you need to water and then to ensure you’ve watered deeply enough. Often the surface looks dry, but a light scratch reveals dark, moist soil beneath that doesn’t actually need water. Likewise, you can water for what seems like enough time, only to scratch the surface and find that the water has not filtered down.

Early Blight/Septoria Leaf Spot

By mid-season, you probably will see lower leaves starting to yellow with black/brown splotches.  As the lower leaves die and fall off, the condition spreads up the plant.  This is caused by either Early Blight or Septoria Leaf Spot.  Both are very common fungal diseases in our area and merely need humid weather to thrive.  At low levels of these diseases, fruit production isn't impacted. Merely trim off the sick lower leaves, focus on the healthy clusters of fruit and green of the growing tip of the plant, and keep up your fertilizing schedule! Many of us end the season with tomato plants that are missing foliage on the lower half of the plant.

The difference between the two diseases is that septoria leaf spot starts out as small regular shaped brown spots on the leaves that develop gray inner circles as the spots get larger.  Early blight starts with a lot of yellowing of the leaf and brown spots that are more irregular than those of septoria leaf spot.  Tomato plants can have both diseases at the same time which can make identification a bit difficult.  But both diseases are treated the same way so don't worry too much about which disease you have.

If your plant has lots of diseased leaves, especially early in the season, you may want to treat the plant.  If not, the yield of the plant can be impacted. As a starting point, you should remove all leaves that show any sign of disease to minimize the spreading of the fungal spores.  Dipping your pruners into a mild bleach solution (one part bleach to 10 parts water) before each cut can also minimize transferring spores to unaffected stems or plants.  Once infected leaves are removed, spray the plant with a mild copper solution.  It's important to spray the stems as well as the tops and bottoms of the leaves.  There are several brands of liquid copper spray available.  

The copper sprays are the only organic treatment for these diseases that I recommend.  I've tried Serenade (bacterial based) and Safer (sulphur based), but wasn't happy with the results for these specific diseases.  Non-organic treatments are Mancozeb (a combination of zinc, magnesium and a few other things), and Fung-onil (chlorothalonil).  

With the copper sprays, its important to follow the directions.  They work by depositing a very weak copper solution onto the surface of the plant which wears off in 7-10 days.  Ideally, the copper spray should be reapplied every 7-10 days or after a heavy rain.  The copper doesn't allow new fungus spores to take hold and penetrate the surface of the leaves/stem.

The product labels and research materials say that you can use the copper spray up until the day of harvest, and that rinsing the tomato fruits with water will remove any copper residue.  While its always better to make due without any kind of chemical - organic or not, copper sprays are very commonly used by organic farms to treat fungal diseases. Properly used, it's a good tool for the organic farmer.

Even if you do only one or two treatments of copper spray, it can help the plant get through the season without suffering too badly.  And remember to continue applying a good organic fertilizer every few weeks!

Blossom End Rot

Blossom end rot is caused by either low calcium levels in your soil or by inconsistent watering (which makes it harder for the plant to absorb calcium from the soil). If you have problems with blossom end rot, get your soil tested and, if necessary, add crab shells or other calcium supplements to the soil at planting time.

Cracking

Some tomatoes will crack. Certain varieties are more prone to cracking, such as Sungold (radial cracks) and Cherokee Purple (concentric cracks around the stem). Cracking can be caused or exacerbated by periods of heavy rain when the skin of the tomato doesn’t expand quickly enough to accommodate the water taken in by the plant. This is especially true if the rain follows a dry period.

End of Season Housekeeping

At the end of every season, the old tomato plants as well as all mulch around them should be discarded in order to minimize the presence of fungus spores. A three year rotation program is recommended but this isn't practical for many home gardeners. If you do rotate your tomatoes on a three year schedule, don’t plant them where you have been planting potatoes, eggplant or peppers. They should be rotated together as they are subject to the same diseases.

External Resources

See http://www.clemson.edu/extension/hgic/pests/plant_pests/veg_fruit/hgic2217.html  for a good description and pictures of common tomato diseases.