One very successful method for transplanting vine crops into bucket systems: start them in small rockwool grow cubes, then transplant them into larger rockwool grow cubes as an intermediary step, then transplant them again into buckets once the root systems are well established. This photo, and this germination system, is detailed on Howard Resh's hydroponic consulting website.
The resounding answer is “yes”. This is how the bato bucket system is designed to be used. The standard procedure is to germinate crops in some other system, then transplant them into the bato buckets. This is as big a step for hydroponic operations as it is for conventional operations. The more carefully the plants are moved and set up in their new homes, the faster they’ll adjust to their new setting, and the more successful they’ll be.
One standard option is to germinate each seed in a rockwool cube. The cube itself may be held in a net pot, a germination tray cell, or just left in the original rockwool sheet placed on a drainage tray. Then the net pots or trays are set up in an environment conducive to sprouting. While this varies by crop, ideal germination conditions generally range from a temperature of 50F to 80F, humidity from 40% to 60%, moist but not wet growing media, and air which moves very gently but is not allowed to stagnate. Lighting won’t be needed until the first leaves emerge, but after that point most crops need fairly intensive light levels for at least 12 hours a day. These conditions can be provided in a variety of ways, ranging from a seedling tray with a clear lid on a sunny window, to a dedicated germination chamber where all the environmental conditions are computer controlled.
Watering is critical at this point. While the seedlings don’t need nutrients right away, they definitely need the correct hydration and humidity levels. This is one of the most intensive phases of production, when the grower must frequently check the crop to ensure proper conditions. While lighting can be put on a timer, the seedling trays may need to be lightly watered numerous times a day. While a full discussion of seedling germination goes well beyond the scope of this section, growers can find plenty of germination guidance elsewhere in books and online. We’ll keep our conversation here to the process of transplanting young plants into the bato bucket system.
Once the seedlings are well rooted, the grower can then transplant them into the bato buckets. When transplanting young plants into a bato bucket system, the two biggest concerns are the growing media, and the irrigation cycle. The plants may have been germinated in one growing medium, for instance rockwool cubes, then transplanted into buckets using some other growing media, for instance gravel or hydroton. In this instance, the grower needs to ensure that the young plants are carefully placed into the bato buckets and fully covered by whatever growing medium is in the bato buckets. For those growers who are using the bato buckets as a mini deep water culture system, the transplants will be in net pots and the net pots will simply slide into the openings within the bato bucket lid. For all the other variations, the bato buckets should be about half-full of growing media prior to transplantation, and then each young plant covered with more growing media when transplanted. Be particularly careful at this stage not to snap off any young roots, since those exposed roots will be the first to venture into the bato buckets. Also ensure that each bucket’s drip irrigation system is directed into the growing media which came with the transplant (for instance, into the original rockwool cube or net pot), since the roots are all still concentrated there.
Transplant shock is an issue for hydroponics growers just like it is for conventional growers. Thankfully, the grower can take several steps to help minimize transplant shock for the seedlings. First, the grower may want to harden off the seedlings just like in conventional production, so that the young plants can get used to their changing environment slowly. This procedure will vary widely depending on the variations between the germination conditions and the bato bucket environment. For bato bucket systems which are already enclosed within a controlled environment setting, the conditions between germination and final location may be minimal. In that instance, very little hardening off will be needed. For smaller systems where the seedlings were raised in a protected environment and the bato buckets are more exposed, then the young seedlings should be gradually switched over from that protected environment to that more exposed environment. If lids are on the seedling trays, take the lids off on warm days and then progress to leaving the lids off entirely. If the trays were in heating mats, turn down the thermostat on the heating mats to more closely match the ambient temperature which the plants will have in their final location. If they are on supplemental lighting, shift the lighting time/intensity over slowly to match the conditions for mature production. And if the seedlings were on a drastically different irrigation cycle than what the grower will use for mature production, switch over that schedule slowly as well.
The above cautions are most important when a group of young plants are going to be coming into a system which already includes mature plants. In that setup, the young plants must blend into the conditions and schedules already in use by the older plants. This is where hardening-off is the most important, since the mature plants can’t really all be taken back to seedling conditions. This situation is typical of a mid-sized operation which features mixed-age plants throughout the year. Smaller scale operations may not have this issue, instead relying on either seasonal production where the bato bucket system is only up and running during the main production phase, typically early summer through late fall. If that’s the case, then all the plants are maturing at the same time, and the weather is gradually going to match their germination conditions anyway.
Ironically, large-scale operations might also have a variation on this approach, known as an all-in-all-out approach. In this management style, a crop is managed in waves or plantings which each have a dedicated growing space. At any given time, there’s a portion of the crop being germinated, a portion of young plants growing towards maturity, a portion in mature production, and a portion which has been harvested and the equipment is being cleaned and repaired prior to the next growing cycle. Entire greenhouses can be managed in this way. This gives large operations the chance to optimize all aspects of the crop’s life cycle, while also always having plants in production. In this setup, the plants would be germinated in their own germination chamber or house, then transplanted into the waiting bato buckets as soon as they’re ready.