March allotment garden

Last revised: 06 January 2019

Seasonal reminders, hints and tips.

Companion planting

Nicotiana, discourages cabbage white butterfly away from brassica by the smell. Sow under cover now or directly sow early May.

Nasturtium, discourages aphids from peas and beans. Sow under cover now or directly sow with the pea and beans.

Sweet pea, sow near or in same rows as peas and beans, Flowers will attract pollinating insects.

Sweet pea can be forced into bushy growth by cutting out the main stem when a few side shows have appeared, which are allowed to grow on.

Spring onions companion with carrots to deter carrot root fly. The spin of is the smell of carrot discourages onion fly.


Starting parsnip can be hit and miss. Some people prepare seeds on a damp kitchen towel in a bowl, kept in a dark place until seeds show shoots. Plant these out as soon as possible, before they get more than an inch (2.5cm). Avoid damaging or handling roots as this causes forking and stump root heads.

Parsnip requires loose, light, airy and fine soil, free of stones. This is rare on our plots unless you are lucky or have a raised bed of good soil. The roots need to grow deep and freely. Sow thinly in one inch (2.5cm) deep rows about 12 inches (30cm) apart. You can tray beetroot or other quick salads between the rows, so mark them clearly. When the parsnip seedling appear, thin out to 6 to 8 inches (15 to 20cm) apart. Germination takes about one month.

Slugs and snails

Pests will be appearing at this time of year. Using your preferred treatment or defence, protect young plants, seedlings and shoots.

More sowing

A plug tray consists of many 1 inch (2.5cm) pots which you fill with fine compost. Sieve multi-purpose compost if necessary to remove stones and large material.

Start off leaks and brassica in with one or two seeds per plug. Lightly cover with compost, and dampen. Cover with plastic or paper to avoid frost damage or excess sun. Check regularly for growth appearing and then remove cover. Water sparingly with fine rose spout, don’t allow to dry out.

If the seedlings show signs of becoming leggy with too much stalk and few leaf, move to cooler place. Thin out the weak plants.

Eventually the plants will be large enough to handle easily to plant out or put into larger pots.


Many people rely on Easter as trigger points for planting potatoes. Be conscious of your plot conditions and possibility of being too wet. Delaying until end of April or early May will still give time for an ‘early’ or ‘second early’ potato crop to succeed. For example:

Fruit tree and bushes

Look for winter damage and remove broken branches. Otherwise pruning is not advised when sap is rising.

Blueberry plants will benefit from a top dressing of ericaceous compost or an ericaceous feed.

Plot tasks

Allotment paths

Grass paths will need trimming to reduce growth of couch grass into your plot.

If the path surface is reasonably dry, perhaps after a few sunny days, use a mower to cut the grass. The clippings can be added to compost heap or spread over potato rows, around other plants to feed the soil.

Horse Tail or Mares Tail weeds

This pernicious weed looks like a small Christmas tree or fern, with several shoots growing in patches.

Ideally the plant needs to be dug out down to root level which may be more than a fork depth. Be sure to get all the stem and roots. Bag up and dispose at Council compost tip.

If infestation is significant, contact the site manager who may be able to assist by applying chemical to kill the weed. The usual shop sold weed killers with glyphosate are not effective unless you catch the very young bright green plants and apply treatment weekly until dead.

Prepare a seed bed

Over winter the ground surface will become compacted by rain and wind. For planting the surface needs to be weed free and lightly forked to loosen the top 3 to 4 inches (about 10cm).

Select a suitable area to work on, say up to 4 metres, and thoroughly weed the the area. Lightly fork over and cover if you wish. Leave for 2 to 3 weeks, then hoe out any new growth and lightly fork over. Repeat as necessary.

Essentially you remove all likely new weed growth which allows planting or sowing your crop in rows or blocks. Now you know where the new plants should appear and can weed out anything you do not want.

Covering the ground with fleece or sheet for a couple of weeks before planting will help warm the surface and keep off frost.

Green manure

If you have a patch of ground to remain bare for the year, consider sowing phacelia green manure. Phacelia tanacetifolia is a versatile plant that will provide valuable cover crop to reduce weeds and flowers to attract beneficial insects. When cut down, before it reseeds, the dead material can be composted or easily dug directly into the ground, and is a nitrogen rich and fibrous supplement. , You will have cleared the area previously, wet or compacted soils reduce germination success. Rake in seeds about one centimetre. Contact site manager for supplies.

More information about green manure