Vegetables: transplanting

Unless sown directly into their final positions, sooner or later, young vegetable plants have to be set out in the soil. This a crucial stage when the plants are vulnerable to stress from cold and drought, and also vulnerable to birds, slugs and other pests.

Vegetables: transplanting

Vegetables: transplanting

Quick facts

Suitable for Young vegetable plants
Timing Late winter until mid-autumn
Difficulty Moderate

Suitable for...

Most vegetables can be raised as transplants and are then easy to set out. Here are the most suitable, including the preferred method/s of raising:

Ones that transplant poorly or need special care include:

  • Beetroot – cell trays as clusters of plants
  • Carrots – short root cultivars in small pots, but best not attempted
  • Florence fennel – small pots, ideally biodegradable ones to minimise planting shock
  • Parsnips – not worth attempting for most gardeners, but sweet pea tubes have potential for success
  • Radish – cell trays, with care
  • Swedes – cell trays, with care
  • Sweetcorn – deep cells, pots or sweet pea tubes
  • Turnips – cell trays, with care

When to transplant vegetables

Plant out when:

  • Roots have just filled the potting medium in cell trays or pots
  • Bare root transplants have five true leaves (brassicas) or can be easily handled (lettuce, onions) or are pencil thickness (leeks)
  • When risk of frost is past if planting tender crops such as runner beans or sweetcorn
  • Before plants develop yellow or purple coloration indicating nutrient deficiency
  • Before plants become difficult to water without wilting. Drought stress is very damaging to young vegetable plants

How to transplant vegetables

When transplanting vegetables:

  • Aim to minimise the damage to the roots and slowing of growth (slowed growth delays maturity and reduces final yield)
  • In extreme cases, the ‘check’ to growth of transplanting can lead to ‘bolting’ or premature seed head formation instead of the expected roots, hearts and curds
  • Harden off transplants raised in greenhouses for two weeks before planting by subjecting them to cooler, better ventilated conditions to reduce the check caused by transplanting into the open
  • If plants appear to be soft and fleshy and therefore vulnerable to weather-related stress, cover with fleece for at least a week after planting
  • Some plants are vulnerable to pests such as cabbage root fly after planting, and protection with fleece, insect-proof mesh or, in the case of cabbage root fly, collars at the base of the stem should be put in place at planting time
  • Starter fertilisers applied at transplanting can help rapid recovery from transplanting. Make a high phosphorus fertiliser at half the recommended strength and apply 250ml per plant to the planting hole

Bare root transplants

Plants and vegetables such as leeks and cabbages are slow to mature and take up a lot of space if sown in their final positions. To make better use of space, they are best soil in rows in a seedbed, then lifted as bare root transplants (i.e. the soil knocked off the roots) as young plants.

The term ‘bare root’ may also be applied to young plants extracted from a seedtray.

  • Water well about a day before lifting to ensure the plants are well supplied with water
  • Leeks should be no more than pencil thickness, and cabbage family or brassica crops should have 5-7 true leaves
  • If plants have been raised under cloches or in a coldframe, increase ventilation for two weeks before planting
  • Keep lifted plants in a shaded place covered with damp sacking or newspaper if not planting out immediately
  • Plant brassicas by making a hole with a trowel, big enough to hold the transplant’s roots
  • With the exception of leeks, place the transplant in the hole up to the depth of the true leaves, and fill the hole with water several times allowing to drain each time
  • Firm the soil around the plant – transplants are sufficiently firmed in if the leaf tears when you try to pull one out of the ground
  • Plant leeks by drawing a groove or drill in the soil with a hoe and make planting holes with a trowel or dibber. Place one leek in each hole and water carefully. This will cause enough soil to accumulate round the roots. Dipping the leek’s roots in a bucket of water before planting will make the roots dangle, easing the job of getting them into the planting hole
  • Although shortening of roots or trimming foliage is sometimes recommended to make the plants easier to handle or in a misguided attempt to reduce stress on the plants, in fact this reduces the plant's capacity to recover. Avoid trimming as far as possible
  • Shading is also detrimental and should only be necessary in the hottest weather
  • Plants treated in this way often need no further watering for several weeks, but if plants wilt or appear stressed, apply water

Pot- or cell tray- raised transplants:

Pot- or cell tray-grown plants are especially easily transplanted. Since the potting compost comes with the plant and the roots are undisturbed, plants raised in this way suffer minimal transplanting shock. However, they can be more tricky to tend, being prone to drying out or becoming pot-bound.

  • Water transplants and the transplanting site the day before planting
  • Take out a hole big enough to accommodate the root ball with a trowel or other implement
  • Plant firmly, aiming to plant no deeper than the transplant was in the original container
  • Keep watered until the plant roots out into the surrounding soil, generally after 14 days

Problems

Potential problems include:

  • Drought: if plants wilt or shed lower leaves, water more frequently, aiming to wet the soil to slightly below the depth of the transplant’s roots
  • Yellowing or discoloured foliage: this suggests a lack of nutrients – water with a balanced liquid fertiliser or treat with a foliar feed
  • Failure to grow: apply fertiliser and, in severe cases, consider replanting or replacing plants
  • Some plants die: unfortunately, the occasional loss is likely to occur. Retain a few plants to ‘mend’ any gaps that appear within a month of planting. Later losses cannot, realistically, be made good
  • Plants fail to make satisfactory plants or yield good produce: consider, for future transplanting, whether plants were stressed at or around planting time, infested with pests or were planted too close together
  • Loss of leaves suggests birds (torn leaves) or slugs and snails (holed leaves or damaged from the edges, with slime trails)


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