When to Plant Tomatoes in Oregon

Because the end of the tomato growing season in Oregon is quite uncertain (sometime in September, possibly in October) and because the summertime is relatively mild in Oregon, tomatoes must be given every opportunity for which to mature.

What that equates to is that you shouldn’t plant your tomatoes so late in the season that the fruit does not have enough time to reach maturity.



How to grow tomatoes in Portland, Oregon


On the other side of the coin, if you plant your tomatoes too early, when temperatures at nighttime consistently remain below 50 degrees F, your tomato plants can remain stunted or they can become diseased because they are still very fragile.

The springtime in Oregon is as unpredictable as the fall. This means that correct timing for planting tomatoes in the state is, to some extent, down to guesswork.

Generally, though, the timeframe for planting tomatoes in Oregon is between 1st May and 1st June. At the very latest, plant up until 15th June. 



How to Plant Tomatoes

If you can, reserve the sunniest spot in your garden for your tomatoes (as well as any vegetables you’ll be growing).

If your tomatoes don’t get full sunshine they’ll struggle to make headway.

If you have no space in your garden for tomatoes you can use 5-gallon pots. There’s an advantage in using pots – they are portable. This means you can position them in a spot that enjoys reflected heat.

Should you opt to plant in your garden you’ll want to space your tomatoes at an absolute minimum of 18 inches apart. If they are indeterminate tomatoes the spacing needs to be more than a mere 18 inches. Ideally, indeterminate tomato varieties will want to be 30 inches apart or thereabouts.

Make sure that you plant your tomatoes deep!

Tomatoes grow roots from the stem. You may as well take advantage of this. Pinch off the lowest couple of lateral branches at the base of the stem and plant your tomatoes to that depth.



Caring for Tomatoes

Tomatoes have high fertility requirements. That’s because the plants take a while to mature and also because the fruit need plenty of feeding to develop properly.

It’s prudent to fertilize your tomatoes at the time of planting. You may wish to utilize an organic fertilizer that is evenly balanced – EB Stone Organics Tomato and Vegetable Food is a good one.

You can make a second application of the same fertilizer or one that is lower in nitrogen content once the fruits start setting.

Your tomato plants will very likely be in need of support. If you opt for stakes, it’s sensible to bang the stakes into the ground when you’re planting your tomatoes. If you prefer to use cages, you may want to ‘cage up’ your tomatoes at this time also – just after they’ve been planted. Staking early helps to avoid root damage. Caging early helps to avoid damage to the foliage.

You may or may not wish to prune your tomato plants. I do tend to prune mine but only very lightly. 

Yes, I take out the suckers. The suckers are the fresh growth that appears at the axis of the lateral tomato branches. The growth of suckers is only vegetative. That means there is no fruit. Hence, suckers merely take goodness from the plant for no return. 

I also take off any yellowing foliage. 

How about irrigation? 

Tomatoes tend to be resistant to a deficiency of water. They do, though, benefit from regular, deep irrigation. 

Tomatoes do not like to sit in water. You should space out irrigation times so the soil does not remain saturated. One or two inches of water per week is ideal for tomato plants when they are in the vegetative state (i.e. no fruit yet). 

Once the fruit begins to set irrigation requirements alter. 

Reduce the quantity of water given. This will encourage a shift over from the vegetative state to the reproductive stage. It helps to speed up setting of and maturing of fruit. 

When you reduce irrigation not long before the time for harvest it helps to reduce the moisture content within the fruit. This, in turn, concentrates sugars and makes the fruit more flavorful and less mealy. 

Plus, if you deep water when your tomato plants are fruiting it can lead to fruit crack and even to fruit explosion. 


How to grow tomatoes in Oregon

As a Recap

Planting: Plant your tomatoes in Oregon between 1st May and 15th June. Either this or when night temperatures consistently reach a minimum of 50 degrees F. 

Location: In a warm place that gets plenty of sunshine. 

Planting: Plant tomatoes deep. Bury the stem up to the first lateral branches. Snip off the lowest lateral branches. 

Feeding: When first being planted feed your tomatoes with a balanced organic fertilizer. When the fruit begins to set fertilize again but with a fertilizer that is low in nitrogen. 

Support: At a minimum, use a stake for each tomato plant. Cages are definitely better for indeterminate tomato plants (which grow much larger than determinate tomato plants). 

Pruning: Pinch out the suckers and any foliage/ branches that are yellowing. 

Irrigation: During the vegetative phase water frequently. When fruit begins setting water only once or twice weekly. 


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