It had been 4 years since we grew and documented journals on growing strawberries from seeds in Singapore.
With the compilation of data and observations from our plants, we began to test what we hypothesized about strawberries in the tropical zone since 2017 and these were some of our findings.
The parameter for our learning journey was to grow from seeds, in natural SG environment and not used any automated systems. We wanted to grow cool seasoned plants with zero or little carbon footprint as possible to keep growing costs down and see how they adapt to our climate. Heirloom Alpine Strawberries were chosen because they thrived in containers, tasted better and have many varieties from seeds. Runner-less varieties were preferred due to lack of space.
There was a lot of misconception about the winter effect on strawberries in our gardening communities.
First, winter is not necessary for strawberries to fruit. Strawberries can fruit in our climate, regardless of varieties. However white and yellow varieties took a longer time to flower in our natural environment.
Gardeners who lived abroad shared that their strawberries improved every season and more often than not, they did so without too much maintenance beyond the normal tilling and fertilizing.
Their fruits sizes also improved over the years. In the winter months, these strawberries grew wild and remained outdoor.
We made the following observations on our 2 years old plants and feedback from other gardeners. Gardeners with high tech systems concurred on fruits sizes.
- Fruit sizes remained small, maximum length was 3 cm
- First harvest yielded the highest quantity of fruits than subsequent harvests.
- Did not enter full dormant stage
- Hardy plants, survived hot, wet and haze conditions
Fact – strawberries are frost hardy meaning they endured winter well and usually emerged from melted snow in Spring to grow again. Some did not return, only healthy plants returned. In our climate, healthy plants also returned to fruit after an adequate rest period. Length of time was dependent on varieties as well. For example, the hardier red garden variety was about 4 months while the whites took longer, about 6 months. Observation was based on soil based plants.
Fact – Regardless of climates, from seeds, fruits size for the first harvest was small. Not larger than 3 cm.
We looked into the forcing culture of greenhouse strawberries in Japan. A paper published by Atsushi Yamasaki (Field Crop and Horticulture Division, National Agriculture and Food Research (NARO) Tohoku Agriculture Research Center, Japan), prescribed artificially creating an almost winter environment, to force plants to rest so that they can renew energy to yield better crop.
This would required a cold room environment, an ideal temperature range of 9 to 15 degree Celsius and another winter element. Can you guess what it is?
At this temperature, greenhouse strawberries did not enter the full dormant stage of outdoor plants in the winter. When they returned, these plants start flowering instead of sending runners.
NATURAL FERTILIZER, HIGH POTASSIUM (K) FOR FRUITING
With this method, greenhouse strawberries were manipulated in an artificial environment to fruit all year round and with each crop, be able to harvest bigger fruits. Aside from these winter rest tweaking, strawberries were grown as naturally as possible. Bees were housed indoors to pollinate flowers as needed. Organic compost was preferred.
In summary, strawberries do not need winter to fruit. The cold is needed for them to rest, so that these plants renewed energy to grow better. Size of fruits improved over seasons. The older the strawberries were, the better they get, fulfilling what we have all understood from gardeners who lived abroad.
Thus, for local gardeners with deep pockets and want big fruits, consider investing in a cold room. Create an artificial indoor winter environment, to enjoy bigger size (zero pesticide) strawberries for the family. Commercially, this is not a sustainable method because our cost of energy is too high compared to our neighbors with natural cool environment.
For the rest of us, we can still grow and enjoy homegrown strawberries and be able to maintain our plants for years by keeping them healthy. WORKSHOPS are available to share how to tweak our indoor environment without too much hassle, among other tips and handling work.
We tested different pots depth for all our plants because of space constraints. As long as basic needs of strawberries plants were met, they can fruit on time (within 5 months) without too much trouble.
Plants with cooler roots, grew better with ease. We also grew in modified plastic recyclables with this need in mind when we upcycled them for growing.
When the heat was suffocating during our hotter tropical months (May – September), strawberries plants drooped often. Non-red varieties (white or yellow types) suffer heat related stress more than the common red garden varieties. They recovered once immediate cooling measures were applied. It could be as simple as removal from hot environment to a shadier area. If no symptom showed, strawberries are sun lovers, able to tolerate summer heat as high as 38 degree Celsius and high humidity.
BEAT THE HEAT With FABRIC POTS
From the above observation, we do not think planting strawberries in the ground is a good idea, unless there is heavy mulching to keep direct heat from penetrating the roots zone. Instead of straw or hay which are expensive in Singapore, we preferred dried leaves, tree barks and coco bales.
Strawberries (over 6 months old) are hardy enough that they survived direct sun in the ground. However any heat stress can delayed fruiting.
Mature plants, over 5 months old, survived heavy monsoon rains, subjected to some conditions. First, soil must drained well and the crown of the plant are set properly. Rot set in if leaves and crown remained constantly wet.
SOIL vs. KRATKY
Soil based plants produced more fruits (80 – 120 small berries total) than plants grew in KRATKY (50 fruits) over a 4 months window, even though the latter medium is cooler.
Time to arrived at flowering stage is faster for Kratky than soil based plants.
Second generation plants yield less fruits than their parent plants but arrived at flowering stage earlier.
It is from the third generation that we observed better acclimated plants with similar traits of their bountiful parents with less heat issues.
Soil based of these seedlings flowered at 3rd month and fruits developed faster. In Kratky, flowers showed in the second month.
RUNNERS vs. SEEDS
Our runner-less Alpines showed runners when they were stressed. The reasons varied from a near tear in the stem or over fertilizing.
If runners are rooted, fruiting is usually delayed.
First flowers from Alpine runners tend to dry up.
If runners were rooted, they often sent out more daughter plants instead of flowering.
The above plant remained fruit-less for over a year. When flowers showed, they did not turned until 2 years later. Only three fruits developed well in this period.
From observation, it seem strawberries can only do one thing at a time.
A Puzzle still waiting for answers – Is winter a deciding factor for runners / hybrid plants? Why did overseas strawberries’ runners produced fruits within the year and ours could not?
COLD TO HOT CLIMATE
Mature plants from cold to hot climate do not immediately produced fruits if the fruits are not present on the plants when they arrived.
Acclimation to a drastically different environment took over a year. Fruiting were delayed, 1 to 2 years.
Most did not survived.
In the West, gardens centers only sell starter plants suitable for their zones, to allow plants to adapt quickly. Adapting is easier within the same climate.
Thus we preferred to grow from seeds. From day 1, in our climate.
HEIRLOOM vs. HYBRIDS, soil based
Heirloom Alpines from seeds, produced small berries but compensated with quantity (80 – 120 fruits over 4 months), usually within 5 months from seeds.
HYBRIDS produced larger fruits in lesser quantity and took a longer time to fruit ( 6 months to over a year), usually grown from a mature runner plant not seeds. Supermarkets’ fruits seeds (Korean strawberries) have these characteristics too if they fruit. With hybrids, the risks are that seedlings do not grow true to parent plants or no fruits at all, only runners.
Based on these observations, we continued to grow from seeds rather than hybrid or runners plants. With seeds, we enjoyed different taste from varieties and have acclimated plants within a shorter time than the latter.
Rather than bigger fruits, we chose many small berries from different wild varieties within the year. Seeds from acclimatized parent plants also grew faster.
No matter the decision, it is still ultimately the grower’s choice.
Growing own strawberries will always be a special experience for the whole family.