Tomato Planting in Calgary
“When is the right time to plant my tomatoes?”
There is not a single answer for this question and optimal dates often change between
years and locations. In order for you to make your decision, you must take into
account Calgary’s average last frost date, the weather forecast and your soil
temperature. Tomatoes cannot tolerate any frost, so if you plant them too early
and they get frosted, you will have to replace them with new plants. Calgary’s
average last frost date is May 23rd so that should be your absolute
earliest planting date. Because this is an average date, remember that there is
a 50% chance a frost will occur after May 23rd, so be ready to cover
them if necessary. The weather forecast is
important since
it gives us a view as to whether we are going into a warming or cooling
trend. The coming week’s forecast looks
quite good, with frost seeming unlikely, although we all know that Calgary
weather can be quickly influenced due to our location near the mountains.
Very important to consider is your soil
temperature. Tomatoes are tropical plants which like warm soil. If your soil is
still very cold, planted tomatoes will just sit and not grow. For me, my home
beds are still cool, but my raised bed at the community center is warm. Even
with this, I won’t be planting my community garden until next weekend when
things will be even warmer and the chance of frost is very low.
This
year, because of the cold spring we could not get our plants outside into
really good sunlight so they have grown quite tall and thin. This is not an
issue since we will make sure to plant them deeply to build the biggest root
systems possible. In an earlier article we had discussed that when re-potting
tomato seedlings we can develop a bigger overall root system by taking
advantage of the plants ability to send out roots along its buried stem. We
will do the same thing again as we plant them out into our gardens. Plant them
more deeply than in their current pot so roots will grow along the buried stem
which is better for our dry conditions.
You
should prep the plants before planting by trimming off all of the leaves which
will be buried when you plant them deeply. The picture shows where to remove
leaves, and as well, an indication of how deeply to plant the stem. We remove the leaves to avoid the issue of
having them continue to grow and keep popping out of the ground all summer long.
What if we have
very tall plants? Not a problem since they can be planted on their side to
cover up even more of their stems. The final 2 pictures show how to do this,
and for a couple of my plants this year I will be using this technique.
Good luck with
your planting, and we’ll see you at the gardens.
Compost
Right now, our community garden group has
been blessed with a large pile NNof top quality compost, specially shipped in
for us to use in our plots. The pile is
getting smaller by the day, so you need to move quickly if you want some! It is
located just west of the community centre and with the tools and wheelbarrows
we have at our disposal, it could not be easier to apply.
For
tomato growers, a generous amount of good compost worked into the soil is considered
one of the necessary ingredients for success. Compost, aka black gold, lightens
soil, adds humus, holds water and provides nutrients for plants as it rots
away. Our beds have clay based soil so
the compost can help to lighten it, making it easier for plant roots to grow.
If the compost is well mixed into the soil as an amendment it will help retain
moisture as well, something which is important for Calgary gardeners.
How do you start? Applying compost properly
is a bit of work, but it will pay off with improved plant growth and yields. Dig
a wheelbarrow full of compost, dump it on top of your bed, use a bow rake to spread
it out evenly, and then dig/mix it into the soil with a garden spading fork. Mix
it in to the depth of the fork tines, about 8-10 inches. Mixing is important
since the greatest value is only realized when it is mixed with your soil.
There is little value in simply top dressing your bed since compost dries out
more quickly than soil, will not lighten the underlying soil, and will stop
rotting when it is dry. Complaints about the compost “drying out too quickly”
will come from those who just dump it on top of their bed as opposed to mixing
it in as a soil amendment.
One last tip is to ensure you mix it into
your soil right up to the inside edge of the boards. Hot weather crops such as
tomatoes and cucumbers are not shy about having their roots grow right up
against the warm boards, so you want that soil to be as fortified as the soil
in the middle of your bed.
Determinate versus Indeterminate tomatoes
During the rush of the community tomato seedling sale you
may have picked up one or more of the few `determinate’ varieties being offered
for sale. To find out, check the variety tag to see if you have any of Independence
Day, Polbig F1, Bush Beefsteak, Arctic Fire and/or Celebrity F1.
Everything else we sold (Sun Gold, Sweet Million etc) was an
`indeterminate’ variety.
Indeterminate plants are `vine’ tomatoes which produce fruit
along the length of the vine, while determinate plants are `bush’ tomatoes
which produce their flowers & fruit at the end of branches only (see
images). In most cases, determinate plants stop growing while they are fairly
short, making them more manageable.
Neither type (determinate/indeterminate) is better, but each
has to be treated in a slightly different manner in your garden in order for
you to be successful.
Determinate (bush) varieties should not be pruned, can be contained
and supported by tomato cages, and do not need to be staked for support. Because
the plant terminates each branch with a flower axil, the size of the plant is
controlled and the fruit tends to ripen within a concentrated time period of
time. Early determinate tomatoes will flower, fully fruit & begin to die
within our short Calgary growing season. If you have a determinate variety from
the sale, just remember “use cages for support & no pruning.” The side
shoots should be left on determinate varieties.
Indeterminate (vine) tomato plants will need to be
vertically staked for support since they will grow out of standard tomato
cages. You can start them in a cage, but
be prepared to add a stake later if you want to control the plant. As well they
should be `pruned’ for best fruiting results. In our context, pruning means
removing side shoots from the main stem. Because these vines will grow
indefinitely – or until they are killed by frost - the fruit they produce
ripens along the main stem over an extended period of time. In our climate with
a killing frost, you will end up with lots of green fruit at the end of the
growing season.
As an fyi, we will be producing a detailed
article on proper pruning techniques and options, and doing an in-garden demonstration.
Re-potting
When re-potting tomato seedlings
we can develop a bigger overall root system by taking advantage of the plants
ability to send out roots along any buried stem. In Calgary, we want the
biggest root system possible to help the plant survive in our dry climate, and
I have found this technique helpful to do so. Please note this technique does
not necessarily apply to other types of flower & vegetable seedlings.
The new pot should be deeper
than the original one. Remove the tomato from the original then place it
directly into the bottom of the bigger one, before adding any new soil. Fill in
the spaces around the old root ball with new soil and add enough to ensure an
additional length of the exposed stem becomes buried (see diagram). Within a
few days, new roots will begin growing along the full length of the buried stem
and these will help sustain the plant in addition to the original ones. Be sure to remove/trim any leaves which would
become buried in the process.
This
method will also provide additional stem stability, and we will employ it again
when we finally put the plants out into the garden.
After purchasing your tomatoes from the Mid Sun Community Garden seedling
sale on Satuday, you may be asking “What do I do next?” or “What steps do I need to
follow to ensure success?” Here are a
few pointers which can help you be successful.
Even though today (Saturday) is cold, the trend
for the coming week is one of general warming and it will be important to get
your plants out, “hardened off” & into the outdoor sun so they can grow
stronger. “Hardening off” tomatoes is the process of getting plants which were
raised indoors under lights to a point where they can be grown in full sun. The
process in tomatoes is similar to how we ourselves slowly increase our time of
exposure to the stronger spring sun to build up protection. Humans can get a
sunburn, tomatoes can get a sun scald (see picture). Sun scald is not lethal,
but it is unsightly and it will definitely slow the growth of young plants.
Hardening off tomatoes takes about a week of gradually
increasing exposure to sunshine to fully transition from indoor light to full
sun. To start, begin by locating the plants in shade with no direct sun. After
a day or two, re-locate the plants into brighter shade with an hour or so of
direct sun (maximum). From there,
gradually add hours of exposure to direct sunlight each day until the plants
are capable of handling full sunshine.
In Calgary, because night time temperatures remain so low,
you will typically want to bring your plants into the garage at night to ensure
they are not killed by frost.
Keep your plants well watered and if they begin to become
root bound, you can re-pot them one more time into bigger containers before you
finally plant them out.
