§ You have sown your seeds in the freezing chillness of the December month. Remember, your extraneous covering of blankets & clothes are still intact over the poly-tunnel. And you might be wondering when and how should you go on about removing the protective covers.
§ Well, the seeds would reside under this shed ranging from 10-22 days depending on weather conditions, after which it will gradually peep through the soil.
§ It will be fine to keep everything as it is (covered) until emergence of the cotyledonary (first) leaves.
|Seedlings under poly-tunnels|
§ However, the blankets, rugs or any covers other than the polyethylene sheet shall be removed during the daytime to allow light into the soil. You should peep occasionally to check the status of seedling emergence.
§ The extraneous covering is only a measure to protect the seedlings against the harsh weather & hence, it should be put back in place during the nights.
§ The beds shall be given occasional watering, providing water just enough to maintain the soil moist.
§ After emergence, the poly-tunnel cladding will have to be removed slightly at the ends for the entry of air.
v You should remember the four basic requirement for plant growth & development;
a. Sunlight: In general, almost all crops perform well if they receive uninterrupted radiation from the sun. For this reason, the outer cover of clothes or blankets will have to be removed during the day time. Otherwise, it would lead to the sickly yellowish development of your crops. I bet I made it clear in my earlier post that the extra sheathings are simply provided to resist the entry of frost during nights.
|Right-Outer protective cover removed for light interception; Left-Plastic folded from side for aeration|
b. Nutrients/minerals: If you have made a conscious effort to select a plot left fallow in the previous year, your seedlings will do fine even if you don't provide other organic supplements. In case that hasn't been possible, try adding a little amount of completely rotten organic manure. The previous crop might have depleted your soil of the necessary nutrients. The nutrient requirement will also differ to a great deal with the varying soil types & conditions. Usually, heavy manure application will lead to overgrowth and thereby, makes the seedlings susceptible to disease & pest attack.
c. Water: The daily weather conditions and the soil type will have direct correlation to the frequency of irrigation requirement. Copious watering would be detrimental to the nursery crops. Diseases like collar rot and damping off are very common in heavily watered and manured nurseries. So follow the basic rule of irrigating your nursery just to maintain the soil moist.
d. Air (Oxygen): Air is a vital to plants as it to humans or any other living beings. Hence, provisions should be made for the plants to have access to air the moment they start peeping from the soil. On account of this fact, the polythene sheet should be opened from the sides for the entry of air. Why only from the sides and not the entire plastic? The open space from the sides is enough for allowing air inside. The idea behind keeping the plastic still intact is to retain heat for the faster growth of seedlings. The harmonious combination of these major entities would determine the health & performance.
|Openings for aeration|
|One-month old seedlings (dated 16-1-17)|
Hardening: Let me touch a bit on this aspect of seedling management.
|Hardening of Seedlings|
§ When your seedlings assume quite a good growth and you are expecting it to be transplanted within 10-15 days, it is good to expose the seedlings to the cold air outside.
|Robust stand of Seedlings (dated 10/02/17)|
§ The seedlings shall be left to get acclimatized to the outside/ normal air condition so that they don't suffer from transplanting shocks.
§ This process will equip the seedlings to face the outside environment with boldness.
|Seedlings left for acclimatization to cold air outside|
§ Seedlings transplanted directly from poly-houses or poly-tunnels to the outdoor fields experience shock due to abrupt change in the air temperature.
§ The seedlings cannot resist the change in their environment & some might not survive even.
§ In addition, the growth of such seedlings become retarded while the hardened one will assume fast & healthy growth immediately after transplanting.
|1 month 25 days old seedlings|
All said & done, you should make it mandatory to cover the seedlings at night. If not, you will be losing all your outcome of hard work in a single night. The frosty bite is not going to spare your lush leaves. Unless you are absolutely sure that there won't be frost, never take a chance to keep your seedlings exposed at night.
Having catered to the aforementioned requirements of the plants, you are heading for a healthy bunch of seedlings for your crop in the ensuing season. Well, the reason why I emphasize so much on healthy nursery management practices is not something anyone is unaware of. My motive here is to reiterate everyone on the importance of good nursery management practices for the health of your seedling is going to determine the produce you are going to harvest.
While some farmers of Thimphu practice nursery raising under poly-tunnel, farmers of Paro & Haa remained afar from the idea. With the recent intervention by RDC-OA, where farmers & extension agents of Thimphu & Paro were being trained on the said topic , I am of the view that there will be early production of vegetables from the coming seasons.
Though this method of nursery raising is highly lucrative for farmers as they fetch premium price for their early crops, it also has certain setbacks. Unless you have someone to monitor the poly-tunnels on daily basis, you won't be reaping the same benefit. Hence, the major limitation of the technique is the labor-intense nature of the work involved.
One of the young attendee of farmers training came up with the suggestion to use double layer of polythene sheet to protect the seedlings from frost injury. His idea was that the air retention in between the plastic layers might not permit the frost to penetrate. The idea seems appealing, especially in view of not having to tend to the nursery on a daily basis. However, this is something that needs to go through experimental test to confirm its effectiveness.
|Seedlings ready for Transplanting|