Spinach

Spinach seeds are of medium size, which means they emerge quite quickly when sown direct, as seen in the second gallery of photos below. They also grow well when multisown and transplants grow readily, including as interplants in late summer to early autumn.

• Seeds germinate in five to eight days.

Sowing time

Do respect the sowing times I give in the table above. There are two principal possibilities:

• Sow very early, right at the end of winter and under cover, and then transplant under a cover for the first month at least.
• Sow as summer draws out, to have spinach of a good size by mid-autumn and onwards.

Sowing method

Seeds may be in clusters, which germinate two seedlings on average. Or they may have been rubbed into mostly singles – have a close look before sowing. Clusters are knobbly and irregular in size and shape.

For module sowing, drop two or three seeds in each cell. The number of eventual plants per cell depends on the size of leaf you want to pick.

• Having two plants per cell serves all purposes.
• Having three plants is possible, but picking leaves can be more time-consuming.

Direct sowing

Draw drills that are 5 cm/2 in from top to bottom. If the surface is dry, run water along the bottom of each drill. Space drills at 25 cm/10 in, and sow seeds at one every 3 cm/1 in.

Once seedlings have a true leaf or two, thin them to about 7 cm/3 in between plants for cooking spinach, or half that space for salad spinach.

Pot on?

It’s rare that you would do this, because spinach is hardy and establishes better as a small seedling, compared to a larger transplant. This is especially the case in spring, when any disruption to growth is a possible factor for triggering early flowering.

‍

Transplant size and time

Seedlings can be as small as one true leaf when transplanted, though up to three true leaves is still good. Any bigger and there is more chance of an interruption to growth.

I still find it amazing how we can so successfully transplant two-week-old seedlings in August.

• At the time of going in the ground they look highly insignificant, yet within 10 days they are clearly growing strongly and are well established.
• Then, within a month, they have large leaves ready to harvest!

Transplant/interplant method

Transplants with a small rootball are easy to pop into holes you make with a dibber. The whole process is extremely rapid, and I often interplant spinach during an August weekend course here. Participants lend a hand, and I notice how amazed they are by the speed of it all.

As with so much in gardening, it just takes a bit of practice to use a dibber at high speed – push it in and twist a little as you withdraw it, so that the hole has a clean edge. Your holes are in soft surface material, not heavy or hard soil, meaning little effort is needed.

• Spring plantings benefit from going in deep because they are then sheltered from high winds whizzing above them. Also we cover them, usually with fleece.
• Summer plantings benefit from going in deep because the rootball then stays moist for longer.

Spacing

For salad leaves, space at 22 cm/9 in. For larger cooking leaves, space at 30 cm/12 in.

Spacing is a small snag when interplanting because you need to use the spaces between the existing plants, therefore the new plantings are on a similar spacing. In my examples it’s fine, because lettuce and spinach have the same need for space.

‍

How often

There are two main times you may need to water.

• Firstly in mid to late spring when new sowings, in particular, are growing very fast. They do not have such an established root system as the older plants from sowings of late summer.
• You will probably need to water new transplants in late summer, to help them establish. Also because when interplanted, they have other thirsty plants nearby such as lettuce.

Extra mulch to retain moisture?

This is more about feeding soil than conserving moisture, because the spinach you sow or transplant in late summer goes in at an awkward time, in terms of an annual cover of compost. A suitable and easy time to mulch almost all beds with a 2.5 cm/1 in layer of new compost is in late autumn to early winter, and just once a year.

However, it’s difficult to do this where spinach is growing, with not much space between each clump of plants. Wide-spaced broccoli is easier!

I use either of these two methods, sometimes both if the first application was light.

• Spread a small amount of compost between spinach plants in early winter, when they are quite small and there is space between them for spreading.
• Wait until you clear the spinach in late spring. If the surface is dry, give some water both before and after spreading, to help the compost settle and be in good contact with soil organisms.

It’s good for soil’s fungal organisms to spread some old woodchip as mulch, on paths between the beds. This also makes it even nicer to be out in the garden picking spinach in winter, with shoes staying clean. The mulch thickness is just 3 cm/1 in, of small wood pieces.

‍

How to judge readiness

A good rule of thumb is to pick a few larger leaves once you see the outer leaves of each plant touching their neighbours. If you leave plants unpicked once many leaves are ready, then some lower leaves start to yellow and you lose harvest.

• It’s a myth that only baby leaves are tender. Large leaves of your homegrown spinach will impress with their softness, and develop full flavour too.
• If you pick or cut plants for small leaves only, they cannot grow large or long-lived.
• Pick larger leaves, and don’t cut across the top.

Packs of baby leaves you may buy are from plants that are cut across the top and then live for maybe two harvests, then are cleared while more are sown. They have big machines for those jobs, but we don’t need to do that work.

How to pick

I notice with helpers here how everybody picks differently. Some people do not value the stalk and pick only leaves, which means a decomposing stalk is present when you come to pick again.

In the end it’s quicker to pick the stalks, by pinching them between finger and thumb. They are good to eat but cut them off before cooking if you don’t like them.

• On a first pick, there are the lowest leaves which are green, small and round. They are best picked to eat because they won’t grow any more, they just go yellow and attract slugs.
• Have two containers while harvesting, just one for the harvest.
• Remove damaged and old leaves which you do not want to eat into the other container, to leave plants clean and more pest-free. Remove any slugs and weeds too.

When to pick and how often

During May, the month of most rapid growth, pick every two or three days. At other times, a five to seven-day interval allows leaves to grow sufficiently.

In winter there are few harvests, and none at all in frosty weather. Maybe a few odd leaves, which one values highly! Plus they are sweeter, especially any with a little yellow.

• Spring plantings can crop for two months and then flower.
• Autumn plantings crop for the second two months of autumn and the whole of spring.

The table below shows harvests of spinach that we grew in 2020 on the dig/no dig comparison beds, which receive the same amount of compost. Every year the spinach grows noticeably stronger on the no dig bed.

It was sown on 7th February – three seeds per cell, thinned to two plants per cell, and transplanted on 13th March.

Date Dig bed (kg)No dig bed (kg)Notes20th April0.82Leatherjacket ate one plant from the no dig bed, while spinach from the dig bed is greener than last year27th April.07.46 4th May.23.41Worrying mystery holes, from wooden sides perhaps?11th May.33.37Still some damage19th May.24.25 26th May.40.41 2nd June.21.21Now starting to flower and twisted out, seven weeks of harvestTOTAL1.482.93

Storing

Larger leaves store better than small ones, for up to a week in a bag at less than 10 °C/50 °F.

Saving seed

This is not too difficult on a garden scale, as long as you have up to six plants to enable cross-pollination. It needs about two months from when they first start rising to flower, until seeds are ready.

By midsummer, the stems are growing heavy with seed and need support. We hammer in four stakes to make a square shape around the spinach plants, then run strings around the outside of those stakes to hold the stems upright – see the photo below.

Judging the moment of harvest is not easy. I find they look brown and ‘ready’ before they are dry, so best wait a little if not sure. Then twist out plants and hang in a ventilated place to dry some more.

Two to four weeks later, you can rub seed clusters off each stem and into a bucket. Some old leaf will also fall in and needs either pulling out or winnowing in a breeze, using two buckets, as in the photo below.

‍

Slugs

They are a pest in many climates, and the photos below suggest how no dig can help to reduce their impact. I find that there is always some slight damage, but that strong plants sown at the right time and in fertile soil suffer less damage than weak plants.

It’s more about prevention than cure. Nonetheless, if you are suffering big problems, go out at night with a torch and either a knife to cut the slugs or a bucket to collect them, then adding salty water.

Other pests

• Lately, perhaps with a warming climate, little green caterpillars have been causing significant damage on some autumn spinach here, and chard too. They make larger holes than slugs, and less round. If we find any while picking, we squash them.
• Leaf miner damage shows as pale patches of leaf which are dry and papery, but they should not be a major problem. We often suffer just a little damage and remove the damaged leaves to compost.
• Leatherjackets are sometimes present in spring and eat the main stem of a few plants, which then fall over and die. If you see this, use a trowel or your fingers to scoop out the soil and compost around the roots of an eaten plant, and you may well find the brown, leathery grub. It needs removing before it can move along to eat another plant – leatherjackets are voracious.
• Sparrows and pigeons may peck spinach leaves – bird netting is your solution for this.
• Deer graze on spinach, with a very inconvenient way of chomping out the middle of each plant. Rabbits do similar but only when really hungry, here in late winter. I find that bird netting prevents them from eating anything, or, in spring, a fleece cover serves for that, as well as encouraging new growth.

Spinach is often quoted as suffering downy mildew but I have never seen it here, except a little on older leaves. I suggest that you do not need to worry about disease, as long as your soil is healthy and you sow at the best times.

‍

‍