Year-Round Growing on the Farm and Garden, starting now

At the Organic Growers School Conference, Ira Wallace and I co-presented a half-day workshop (twice!). I uploaded the slides as a pdf on SlideShare.net, and here they are.

Those who start early in “spring” (late winter) might get earlier crops, but when is it worth it?

Some crops are just not going to thrive if you start too soon: cucumbers, peppers, and even tomatoes, for example. Make sure you can provide conditions that meet the minimum temperature requirements for these tender crops. See my book Sustainable Market Farming, for all the details. We used to start these tender crops earlier than we do now. March conditions have become more unreliable, often colder.

If you already have a place to grow protected crops, or you are experienced with rowcover and have plenty on hand, then the signs are good. Crops can be started earlier in a greenhouse or hoophouse (or even on a kitchen windowsill) than you can sow them outdoors. When the plants reach a good size, harden them off and then plant them out in a mild spell, with rowcover for the first couple of weeks. Pay close attention to weather forecasts.

Our greenhouse full of seed flats and sunshine in March.
Photo Twin Oaks Community

“Hardening off” is a process of acclimating your plants to colder, brighter, breezier conditions, so that they won’t suffer when they are transplanted. If you have only a small number of plants, or of flats, you could actually bring them back indoors every night and set them out every morning for 10-14 days. Growers with lots of crops to harden off will make use of a coldframe. Depending on the actual temperature (or the expected night-time low) we might leave our plants uncovered, use rowcover, top the rowcover with transparent lids (“lights”) , and if it’s going to be really cold, quilted covers, weighted down with wood beams if it is the least bit windy.

Our coldframes and greenhouse at Twin Oaks. Photo Twin oaks Community.

After two weeks of hardening off, look for a few days of mild, calm weather to plant them out in the garden. Water the plants well the day before transplanting, and again one hour before transplanting. This allows the cells of the plants to fill up with water, enough to tide them over the period of “transplant shock”.

Even the most skillful of us end up doing some damage to the roots of transplants, and that means the plants have to regrow some lateral roots and root hairs before they can pull in water at the rate they were doing before your ministrations. As you transplant, avoid touching the roots of the plants. Our fingers damage the root hairs.

Okra seedlings in a Winstrip tray in the greenhouse.
Photo Kathryn Simmons

A way to minimize the root damage is to use soil blocks or Winstrip plug flats. These methods are more expensive in time or money than open flats or bare root transplants, but they allow the roots to get “air-pruned” as they grow. When the roots reach the air at the edges of the blocks, or at the vertical slits on the sides of the Winstrip cells, they stop growing, rather than circle around the cell, causing the plant to get root bound. Secondly, these tools work by helping the roots and compost form a coherent block, one that holds together as you pop it into the hole you create in the soil.

Speedling flats are styrofoam flats with tapered cells, and it is possible to slide the plugs out (or gently pull them out) with little damage. Regular cell packs (4-packs, 6-packs etc) can be encouraged to release their transplants by squeezing them at the base of a cell, while holding the pack sideways. Then spread your fingers over the compost around the pant, invert the pack and hopefully the plant and its compost stays as an item, with your fingers either side of the stem.

Transplanting spinach from a Speedling flat. Butter knives are the tool of choice for easing the little wedges out of the tapered cells.
Photo Denny Ray McElya

Hold the plant with one hand by a seed leaf, or if you have to, by the stem. The seed leaves are disposable, stems and roots are not! Hold the plant at the right height, usually with all the stem below the leaves in the ground and all the leaves above ground. Once the plant is in the ground at the right height, hold it there and use the other hand (maybe with a trowel) to push in soil to fill the hole. Firm the soil down quite well, pulling in more soil as needed to leave a level surface. You don’t want the plant to be in a divot, where water can accumulate.

About the degree of firmness: you are aiming to make good contact between the soil and the plant roots, so the roots are not in air pockets, but rather can suck in water from the between soil particles. Don’t firm so hard that you expel the air from the soil and make what feels like concrete the next day. With cabbages, I was taught to firm enough so that if you then grasp a leaf and pull, the leaf tears off, rather than pulling up the whole plant.

Plant for 20-30 minutes, then pause and water in each of the new transplants by hand. Some people will bring a watering can along the row and water each one, one at a time. I prefer to do little batches. At the end of you transplanting session, water the whole row or bed again. try to avoid having piles or dishpans of plants with roots exposed to the air. Definitely don’t take a tea break if you have exposed plants.

Cover with rowcover if needed, or shadecloth if the weather is very bright and sunny. This will just be for a few weeks, helping the plants recover from the transplant shock, and biding time while spring warms up.

If it doesn’t rain, water again the next day (day 2), then on days 4 and 6, then twice a week, then once a week forever after that, until harvest is completed.

A bed of young transplanted lettuce.
Photo Wren Vile

Bare Root Transplants

Lettuce seed bed, with Muir, Jericho, Sierra lettuces. Photo Bridget Aleshire
Lettuce seed bed, with Muir, Jericho, Sierra lettuces.
Photo Bridget Aleshire

Last week when writing about Lettuce Varieties for January I mentioned how we grow all our outdoor lettuce as bare root transplants. From January through to the end of April, we sow lettuce seed in open flats. After that date, we sow in outdoor nursery seed beds, and simply dig up the transplants when big enough and replant them in our raised beds. We transplant 120 lettuce outdoors each week until early October and then transplant in our greenhouse and our hoophouse. We also grow many other crops (all the easy to transplant ones) in open flats, or in nursery seed beds.

This method has gone “out of fashion”, but perhaps it will come back in! Atina Diffley (Author of Turn Here Sweet Corn and Wholesale Success) has written a blog post about bare-root brassica transplants at atinadiffley.com/blog/. She has written a thorough-and-concise 9 page manual Seed Beds: Bare Root Field-grown Brassica Transplant Production.  It includes a chart of pros and cons of bare-root transplants compared to container-grown greenhouse transplants.

Using bare-root transplants does require a bit more attention to technique than popping plugs into the ground. But it’s not that difficult and we train new people every year with success.

Why bare-root transplants?

Bare-root transplants save a lot of time and money, compared to growing in flats. They also save on valuable greenhouse space. The plants get very sturdy, because they have the full depth of soil in which to develop big roots. Starts grown in outdoor seedbeds are already acclimated to cooler conditions than plants in your greenhouse. They are less prone to drying out than seedlings in flats, but do be ready to protect them from bugs.

Which crops work best?

Bare-root transplants can suffer more transplant shock than plugs, so start with “easy to transplant” crops, such as brassicas (cabbage, kale, collards, broccoli, Brussels sprouts, kohlrabi), lettuce, onions and leeks. Tomatoes and peppers are worth trying next. See the Chart “Relative Ease of Transplanting Bare-Root Vegetable Seedlings” free online in Knott’s Handbook for Vegetable Growers. Avoid trying bare-root cucurbits (squash, melons, cucumbers).

Bare-root transplants can be used on any scale, from backyard to large farm. See the impressive photos of huge beds of cabbage transplants in Atina Diffley’s manual. They can be used at various times of year, and from indoors to outdoors and vice-versa.

Spring bare-root transplants started in a hoophouse, planted outdoors.

For the earliest spring transplants, bare-root hoophouse starts are a nice option. For us, onion seedlings overwintered in the hoophouse have worked very well. Seedlings outdoors or in a cold-frame suffer too much winter-kill. We don’t want to fuss with flats in November-February. We’re in zone 7, at 38̊ N. We sow onions in the soil in the hoophouse November 10 and 20, with a backup sowing on December 5. We plant them outdoors as early in March as we can. The onions get to thin-pencil-size by March 1, which we couldn’t do from a spring sowing. Onion roots are tough and thick, not thread-like – they are easy as bare-root transplants.

We sow spinach, collards and kale in the hoophouse in mid-late January and plant them outdoors in early March. This is a lot less work than using flats, and our comparison trials with bare-root spinach showed results were just as good as spinach in Speedling plug flats. We have tried early lettuce transplanted from the hoophouse, but the plants were not as sturdy as those in flats.

Senposai, the Thousand Wonder Green, Credit Kathryn Simmons
Senposai, the Thousand Wonder Green,
Credit Kathryn Simmons

Outdoor bare-root transplants

See my book Sustainable Market Farming, for more details of growing outdoor bare root transplants. We grow lettuce this way from April to September, and fall brassicas in June and July, in one of our permanent raised beds where the soil is friable and free-draining. Also see Atina Diffley’s manual for cultivation tips.

We grow outdoor cabbage, broccoli, collard, senposai and Yukina Savoy transplants in seedbeds for 3-4 weeks in June and July, covered with ProtekNet on hoops. We transplant in July and early August for harvest in October and November. We prefer this to direct sowing, because it is much easier to keep the relatively small seedbed watered and bug-free. For large amounts use an EarthWay seeder. Atina Diffley recommends the leek seed plate for brassicas.

Outdoors to indoors

In September we make an outdoor seedbed for crops to transplant into our hoophouse in October. The late summer hoophouse crops get a few extra weeks to finish up. Because the hoophouse can be warmer than ideal for lettuce germination until well into fall, it often works better to start plants in a cooler location, then move the plants. In September in our climate, four-week old lettuce plants will be a good size.

As well as ten varieties of lettuce, we sow various Asian greens and Brite Lites chard. Nine days later we sow another ten varieties of lettuce, white and red Russian kales, senposai and frilly mustards such as Ruby Streaks, Red Rain, Golden Frills, Scarlet Frills as well as green mizuna. We cover the seedbeds with hoops and ProtekNet and water daily. Transplanting these plants starts October 1 with the fast-growing pak choy, Chinese cabbage and Tokyo Bekana. The other transplants follow, as they reach the right size.

Brassica seedbed protected from insects with ProtekNet and hoops. Photo Bridget Alsehsire
Brassica seedbed protected from insects with ProtekNet and hoops.
Photo Bridget Alsehsire

Stay indoors in winter

In October in the hoophouse we sow short rows of “brassica fillers”, mostly senposai, Tokyo Bekana and Maruba Santoh. These grow fastest, which becomes more important in the dark winter days. We fill gaps in any brassica bed, that occur either because of disease, or of harvesting. In late October and early November we sow filler leaf lettuce varieties and filler spinach. These extra plants help us out if something goes wrong, and give us the chance to grow some extra crops after the first ones have been harvested.

How much to sow

Our formula for sowing seedbeds in the hoophouse is to divide the final row length of brassica plants by 10 to give the minimum length of seed row to sow. These plants will be transplanted 10″-12″ (25-30 cm) apart. For onions (to be transplanted 4″ (10 cm) apart), we divide the number of plants wanted by 20 to give the row feet (67/m), but we sow this amount twice, about 10 days apart. Outdoors for the fall brassicas, we sow around a foot (30 cm) of seed row for every 12′-15′ (3.6-4.6 m) of crop row, aiming for 3-4 seeds per inch (0.75 cm apart). These plants will be transplanted 18″ (46 cm) apart. It’s important to weed and thin the seedlings to 1″ (2.5 cm) apart soon after they emerge.

Transplant age and size

There is quite a lot of flexibility about when a start can be transplanted, but there are accepted ideals to be aimed for. The University of Florida Vegetable Horticulture Program Vegetable Transplant Production page  has a wealth of transplant information. Transplants grown over winter or in very early spring in a hoophouse will take longer to reach plantable size than those sown in spring or summer.

Suitable conditions for transplanting

The ideal conditions for outdoor transplanting are mild windless afternoons and evenings just before light steady rain. Transplanting late in the day gives the plant the chance to recover during the cooler night hours when transpiration is slower. Shadecloth or rowcover can reduce the drying effects of wind and sun. Damp soil is important before, during and after transplanting.

Bare-root transplanting technique

When you dig up your bare-root transplants, leave some soil clinging to the roots, to help the plants re-establish quicker. They don’t need a full handful of soil for each plant. Just dig up a clump and give it a light shake, to leave the majority of the soil behind, and some still on the roots. This means less damage to the root hairs. Be sure to dig deep enough so you don’t damage the tap roots. Water your plants the day before and an hour before lifting (pulling) them. In hot weather, keep the plants as shaded as possible while transplanting.If necessary water the soil ahead of planting.

We use plastic dish-pans to carry our plants from seedbed to field, and I tell people to only dig up what they think they can transplant in half an hour, so that plants don’t sit around for too long. Push the trowel into the soil, using the dominant hand, push it forwards, shake a plant loose from the clumps in the dish-pan with the other hand, and slip a plant in behind the trowel. Pull out the trowel, keeping it in your hand while you close the soil against the stem with your planting hand and the trowel. (Efficient workers keep a hand on the trowel at all times, never setting it down.) Move to the next spot and repeat. When setting out a large number of plants, water every 20-30 minutes if you don’t have drip irrigation running (a bit less often if you do) regardless of the number of plants set out. If the person is skilled and moving fast, and the weather is not outrageously hot or windy, I might let an hour go by before pausing to water. The advantage of getting a lot of plants in the ground proficiently and quickly might outweigh the need to water more often, as the plants are not having their roots exposed to the air for as long when they are planted fast. The hand-watering really helps the soil settle around the roots, and after that the damp soil can wick moisture from the irrigation towards the plant.

Aftercare: water, rowcover, shadecloth

Water your plants the day after transplanting, on days 3, 7 and 10, and then weekly, if it doesn’t rain when you’d like it to. Shadecloth draped over recently transplanted crops can help them recover sooner from the shock in hot sunny weather. We use 50% shade, in 6′ (1.8 m) width, with wire hoops to hold the shadecloth above the plants. This improves the airflow as well as reducing the abrasion or pressure damage done to the plants. The airflow through shadecloth is better than with floating rowcovers. ProtekNet allows good airflow too, and keeps bugs off.

Shade cloth on lettuce seed bed. Photo Nina Gentle
Shade cloth on lettuce seed bed.
Photo Nina Gentle