Big Zac Tomato
Growing Tomatoes in Las
Family – Solanaceae
All too often, this most sought after
garden fruit proves elusive to Las Cruces gardeners.
Based on what I have seen and heard, the reasons are both universal
to every climate and specific to southern New Mexico. Those reasons
• Cold – both the killing kind and cold that slows
growth, making the plants more vulnerable to stressors
• Heat – that effects plant growth as well as blossom
retention and fruit setting
• Wind – particularly in spring when plants are young
• Diseases – from spring through harvest
• Fruit Stress – some exacerbated by local soil conditions
as well as cold, heat and water stress
Cold and Heat Stress
In our region, cold, heat and wind factors are really timing issues
– so let’s start with cold. If you have to start growing
tomatoes early in the season, select cold tolerant, early varieties.
My favorite (grown every year) is Oregon Spring Bush. Grow them
indoors or in a green house under lights and pot them up until they
are ready to start blooming. When transplanting them out before
the last frost, protect them with frost blankets, wall-o-waters
or some kind of cover.
The chart below shows the spring and second season timing for tomatoes.
Even then, it’s not the whole picture of possibilities. Extension
publications recommend a spring planting date of Feb 15 –
Mar 15 only. If you start seed indoors on Jan 15 and pot them up
midway, you can still plant out on March 15. You can also start
later and reduce the risk of cold and heat stress even further.
You can avoid cold and most heat stressors by altering your timing
so that you are growing in the optimum temperature range for tomatoes,
but you will not get the award for the first tomato of the season.
Optimum nighttime temperatures for tomatoes (above
55°F) begin here in early to mid May. If you plan to transplant
out then, your plants will have the best of growing conditions and
not spend many nights and days stalled out waiting for warm temperatures.
Since June is our hottest month, it is the time when most blossom
drop occurs. Transplants set out in May will begin to bloom after
the peak heat and produce tomatoes during late July and August,
depending on varieties and growing conditions.
The heat stress that is most noticeable occurs with days temperatures
above 90°F. However, nighttime temperatures above 76°F also
cause heat stress that leads to blossom drop. Increasing the humidity
around the plants will reduce overall stress during peak heat times
and reduce blossom drop. Using fabric row covers (Agribond) will
increase humidity enough to reduce blossom drop, but not eliminate
it. Once the monsoon rains begin, remove the row covers to avoid
fungal diseases fostered by excess humidity.
Second Season Tomatoes
Our growing season here is so long, that you can even
start a second crop in June and get a good harvest before frost,
without any cold or heat stress; however, an early frost remains
You have two choices – protection or late planting.
The best wind protectors are row covers. Next best are windbreaks.
Setting plants out in May avoids the worst of the windy season.
Tomato row cover and protective skirt
Row covers and windbreak/skirts will protect tomatoes from leafhopper
transmitted curly top virus. Growing tomatoes dependably requires
using some protection from leafhoppers – period. Thirty-inch
tall skirts will stop nearly all leafhoppers and can be left on
through the season as the plants grow out the tops.
Other Common Tomato Diseases
Vegetable MD Online is one of the best sites for information
on tomato diseases
The goal of growing tomatoes is to produce quality fruit; however,
there are many pitfalls on the road to ripe and juicy.
• Blossom End-Rot – is
common here because of our high soil pH that can further limit calcium
availability during periods of water stress.
• Cracking - is common here
during the monsoon season when soil water levels fluctuate
• Catfacing - is common if you
plant early enough for flowering to occur during cold weather or
if you over fertilize young plant.
• Sunburn - is very common here
if shaded fruit is exposed to direct sun light.
The article Blemishes
on the Road to Ripe and Juicy describes the common
fruit problems and provides solutions.
So there you have it, in a nutshell - what to do here to increase
your success with tomato production. Using good culturing practices,
creating optimum soil conditions, watering properly and choosing
the right varieties are also required to be dependably successful.
Good Gardening and Good Eating,
Doña Ana Extension Master Gardener