Training of Vegetable Crops

In Chapter 23, we discussed the details of sowing seeds and the first transplanting stage� For vine crops, it was transplanting the seedlings in their 1½″ rockwool cubes to the 3″ rockwool blocks� The final transplanting to the growing system, at what stage to do this, and subsequent training of the plants through to their maturity are presented here� Procedures vary with specific crops� With all crops at this final transplanting step, you must select the most healthy, vigorous plants first, leaving any smaller, leggy plants last or hopefully to discard them as they should be part of that extra 10% of seedlings that were raised�

With regard to sanitation, there is no point in getting your plants to this final stage of transplanting as clean seedlings and then abandoning those precautions during the final transplantation� That may still introduce diseases� Follow strict sanitation procedures in moving the transplants on carts, in trays, and finally to their placement to the final hydroponic growing system� Keep the seedlings in their original mesh trays until you place them on the slabs or pots ready to be positioned� Do not place seedlings on other nonsterile surfaces before putting them on the slabs or pots� This sounds a little over done, but at any time those seedling roots are exposed to unclean surfaces a disease organism that may be present can enter the roots causing decline in the mature plant as it develops� You have spent a lot of effort in getting the best, most healthy, disease-free seedlings to this final stage so do not jeopardize their continued health through lack of these precautions at the final point�

There are two ways to cultivate arugula, as mentioned in Chapter 23: either sow directly into beds or pots of peatlite substrate or start them in 1″ rockwool or Oasis cubes and transplant to the hydroponic system at 14-18 days�

In 5-gallon plastic nursery pots sow more or less 30 seeds uniformly on the top� Pre-moisten the substrate prior to seeding and immediately after� With pots a drip irrigation system may be used to water or do so once a day by hand using a watering can�

For beds sow the seeds in rows 6″ apart� Be careful to pre-wet the substrate before sowing the seeds� If you want to automate the irrigation of beds place “ooze” or “soaker” hoses one foot apart along the length of the bed� Soaker hoses are thinwalled drip lines of ½″ diameter that have very small holes every 4″ along the hose� This gives more uniform distribution of the water along the bed length� You can make your own “soaker” hose by using ½″ black poly irrigation tubing and inserting 0�5 gph emitters into it at 4″ centers� Do not place drip lines on the emitters, simply

let them drip directly below to the substrate� At 3″ on each side of the irrigation line sow the seeds in line� This can easily be done by using a broom handle or ¾″ diameter pipe to press a groove into the substrate ½″ deep� Sow the seeds into this channel almost touching each other about three to four seeds across� This will give a dense growth of the arugula in the rows and they will spread to the side forming a complete cover of plants in the entire bed� From sowing the seeds to the first cutting, it will be about 4 weeks� When harvesting use a scissors or electric knife to cut sections of the bed at a time� After three harvests, about 3 months, it is best to remove the plants and seed again� If you want continued production, seed half of the bed length every 8 weeks or one-third of it every 5-6 weeks to keep continuous young plants growing that will replace the older ones after their third harvest�

For transplanting to nutrient film technique (NFT) or raft culture systems start the seedlings in rockwool or Oasis cubes� Place 10-12 seeds in the each cube after the cubes have been thoroughly flushed with raw water to adjust their pH to near 6�0� To increase the efficiency of production, as was described in Chapter 23 under “Lettuce,” use two transplant stages� Arugula has the same spacing and a similar growth rate to lettuce, so follow the lettuce procedure� The first transplant stage is at 10-12 days when the seedlings have formed three true leaves� With raft culture transplant them to the nursery raft having 4″ × 4″ spacing� In NFT transplant them to the nursery channel having holes at 2″ centers with channels spaced 4″ centerto-center� They are held in this nursery location for 8-10 days before transplanting them to the final finishing or production boards/channels� They will be ready to begin harvesting within 2 weeks�

If you are not growing a lot of arugula, this extra transplanting stage probably does not justify the additional work� Then, simply transplant to the final production boards/channels at 12-18 days from sowing in the cubes� It is more feasible to use the two-transplant procedure if you wish to harvest the arugula one time at its maturity between 3 and 4 weeks and not make multiple harvests�

When the seedlings are transplanted to the production area use a complete nutrient solution, not the diluted half-strength one used on the seedlings when on the propagation bench�

The cultivation of basil is very close to that of the arugula described earlier, except that it should be transplanted and not directly seeded� If you wish to transplant to pots or beds of peatlite medium, start the basil seeds in the same peatlite mix in 72-celled compact trays� Sow four to five seeds per cell or cube as outlined in Chapter 22� For NFT or raft culture follow the preceding procedures for arugula� The cropping cycle closely follows that of arugula�

The principal difference between arugula and basil is the harvesting method� Arugula is simply cut back to within 2-3″ above the crown area, whereas basil must be trained through precise cutting stages� The first cut of basil is as it reaches three sets of true leaves at the third-to fourth-node� Cut the tops about ¼″ above the node of the leaves� You may think that this is more complicated than growing in soil, but the fact is the procedure is exactly the same whether growing basil hydroponically or

in soil if you wish to maintain a juvenile plant to prevent it from becoming “woody” stemmed� Subsequent harvests take place as the plants produce side shoots with at least three sets of leaves� Repeat this cutting technique with all side shoots as they continue to bifurcate as they are cut back� This produces bushy (multi-stemmed) young growth� However, after about 3 months the plants need to be replaced as they eventually become woody as they mature, especially if you allow them to flower� Seed the new crop about 3 weeks before taking out the older plants so that the down time between crops is reduced to 10-12 days� You may also sequence the cropping so that a portion of the plants are at different ages� In that way, you get continuous production�

Feed the plants with a complete nutrient solution after transplanting to the production system� Optimum temperatures for basil are from 70°F to 80°F (21-27°C)�

Bok choy is transplanted to plant towers, NFT, or raft culture 21-25 days after sowing in rockwool or Oasis cubes� To transplant to the plant towers place one seedling in each corner of the pots� Use the end of a broom handle to indent a hole in the substrate to a depth of 1½″ to facilitate the placement of the seedling with its cube� The crown (area where the plant stem enters the cube) of the plant should be at the surface of the medium� Water the substrate before and immediately after transplanting� You may have to water a few times by hand over the next few days until the roots take hold in the substrate to prevent any possible drying of the seedling cube� After that the drip irrigation system will provide sufficient moisture with a full-strength nutrient solution� Bok choy grows well at temperatures from 70°F to 80°F (21-27°C)� The first harvest is 20-25 days after transplanting when a semihead forms� Of course, you may harvest it at earlier stages, particularly if you want tenderer “baby” bok choy�

If you are growing bok choy in one plant tower, sequence the planting of each pot a few days apart to obtain continued production� For example, if the plant tower has 10 pots, each pot will have four plants, except the top pot that can have eight plants to give a total of 44 plants� If you sow four plants every second or third day you will get plants ready to harvest every day� Unless you are really crazy about bok choy, this one plant tower will be too much for your personal consumption, so why not use half of the plant tower for bok choy and the other half for arugula, basil, or lettuce!